ATOLL RESEARCH BULLETIN 
No. 118 
Ecology of Aldabra Atoll, Indian Ocean 
edited by Dr. David R. Stoddart 
Chapter 1. Scientific Studies on Aldabra Atoll. 
D. R. Stoddart 
2. Geography and Ecology of Aldabra Atoll. 
D. R. Stoddart and C. A. Wright 
3. Summary of the Ecology of Coral Islands North 
of Madagascar (excluding Aldabra). 
D. R. Stoddart 
4. The Birds of Aldabra and their Status. 
C. W. Benson 
5. Observations on the Birds of Aldabra in 1964 and 
1965. 
R. Gaymer 
6. Bibliography of Aldabra. 
D. R. Stoddart 
Issued by 
THE SMITHSONIAN INSTITUTION 
Washington, D.C., U.S.A. 
November 15, 1967 
Contents 
1. Scientific Studies on Aldabra Atoll 
D. R. Stoddart 
2. Geography and Ecology of Aldabra Atoll 
D. R. Stoddart and C. A. Wright 
3. Summary of the Ecology of Coral Islands North of 
Madagascar (excluding Aldabra) 
D. R. Stoddart 
4. The Birds of Aldabra and their Status 
C. W. Benson 
5. Observations on the Birds of Aldabra in 1964 and 1965 
R. Gaymer 
6. Bibliography of Aldabra 
D. R. Stoddart 
Page 
1 
FIGURES 
Page 
1 . Location of Aldabra ................................. 12 
2 . Geology of Indian Ocean islands ......................... 14 
3 . Aldabra Atoll ..................................... 16 
.......................... . 4 Major habitats of Aldabra Atoll 20 
5 . Distribution of the Giant Land Tortoise in the Indian Ocean in the 
Eighteenth Century. a f te r  Rothschild (1915) .................. 35 
.......... . 6 Islands and bathyrnetry of the South-west Indian Ocean 54 
TABLES 
Page 
1 . Previous investigations at Aldabra ....................... 5 
..................... 2 . Endemic species in the Aldabra flora 25 
3 . Group endemics in the Aldabra f lora ...................... 26 
4 . Key to the literature on the insects of Aldabra ............... 39 
5 . Wing-lengths (in mm.) of specimens of Falco newtoni and F . araea . 72 
6 . Measurements (in mm.) of specimens of Dryolimnas cuvieri . . . . . .  74 
...... 7 . Wing-lengths (in mm.) of material of Streptopelia picturata 79 
8 . Measurements (in mm.) of specimens of Centropus toulou from 
Malagasy Region ................................... 80 
9 . List of land birds breeding in the Aldabra archipelago .......... 106 
PLATES (following page 141) 
1. Exposed coastal cliffs, Point Hodoul. Note the extreme dissection of the 
champignon, the absence of a basal notch, and the development of an in- 
tertidal algal platform. 
2. Medium-energy coastal cliffs, east of East  Channel, mid-tide. 
3. Boulder zone on reef flat at low tide, Anse CBdres. 
4. Small pocket beach on medium-energy coast, near Anse Csdres, low 
tide. Note the perched beach above the cliff line. 
5. Pocket beach at Anse ~ h d r e s ,  mid-tide; beachrock in the foreground. 
6. Low coastal dunes, seaward coast near Takamaka. 
7. Moderate coastal dunes, seaward coast near Cinq Cases. 
8. Moderate coastal dunes with coarse grasses  between Takamaka and 
Cinq Cases. 
9. Dunes at the south end of West Island; the intertidal flat in the fore- 
ground is exposed at low water. 
10. Undercut lagoon cliffs, South Island near East Channel. 
11. Undercut lagoon islets, low tide, South Island near East East  Channel. 
The amplitude of the notch is about 6 feet. 
12. Sand-spit at the south end of West Island, colonised by Cyperus 
maritimus and seedlings of Scaevola and Tournefortia. 
13. Pot-holed surface of champignon, South Island close to East Channel. 
Soil is found only on the floors of the potholes and not on the ground 
surface. 
14. Karst landforms in shelly limestone on Ile Esprit. The vertical ampli- 
tude of the pinnacles from the flat enclosed floors to the summit ridges 
is 18 ft. 
15. Platin with Mixed Scrub, three miles southeast of East Channel, on 
South Island. 
15. Incised pools and residuals on the platin surface, South Island, near 
Frigate Pool. The ground vegetarion is Fimbristylis spathacea. 
17. Surface exfoliation on platin near  Frigate Pool, South Island. Some of 
the limestone sheets a r e  completely detached. At the left of the photo- 
graph is a small  a r ea  of mammillate limestone formed by secondary 
deposition. 
18. Flat platin under open Mixed Scrub, showing residuals of brown lime- 
stone 3-4 f t  high, near Flamingo Pool, South Island. 
19. Brown-limestone residual 6 f t  high, near Flamingo Pool, South Island. 
The surface of the residual shows solution furrows. 
20. Seaward fringe of the Mixed Scrub community south of Takamaka. The 
vegetation is sparse, and almost all  the shrubs and t rees  a r e  dead, 
except for  Pandanus. 
21. Large tidal solution hole in champignon near  Point Hodoul, South Island, 
being flooded by the rising tide. Note the basal solution notching on the 
islands. 
22. Takamaka Pool, showing the la rge  Ficus in which Pteropus aldabrensis 
is found. 
23. Fresh  water in a semi-permanent water-course at Cinq Cases, South 
Island, surrounded by dense Acrostichum aureum and Pandanus. 
24. Freshwater  pool used a s  a tortoise wallow, surrounded by Pandanus, on 
South Island, three miles  southeast of Eas t  Channel. 
25. Tortoises wallowing in a freshwater  pool during the morning: one in the 
centre of the pool is dead. 
26. Giant Land Tortoise, Testudo gigantea (Photo: R. Gaymer). 
27. Tortoise on the dry floor of a freshwater pool, during the dry season, 
near  Takamaka, South Island. 
28. Tortoise and a Sacred Ibis, Threskiornis aethiopica abbotti, near 
Frigate Pool, South Island. 
29. Frigate-birds diving fo r  water a t  Frigate Pool, South Island. 
30. Juvenile Red-footed Booby, -- Sula sula rubripes, on Polymnie (Photo: 
R. Gaymer). 
31. Red-tailed Tropicbird, Phaethon rubricauda rubricauda, on a lagoon 
is let  inside East Channel. 
32. Adult Sacred Ibis, Threskiornis  aetbiopica abbotti (Photo: R. Gaymer). 
33. Colony of Sacred Ibis a t  Takamaka, South Island (Photo: R. Gaymer). 
34. Fl ight less  Rail, Dryolimnas cuvier i  aldabranus (Photo: R. Gayrner). 
35. Male Red-headed Fo re s t  Fody, Foudia eminentissima aldabrana, giving 
threa t  display in his  terr i tory.  Note the dropped wings and tail, and 
r a i s ed  head and rump feathers  (Photo: R. Gaymer). 
36. P a i r  of Flamingos, Phoenicopterus rube r  roseus,  wading in a brackish 
--
pool in mangrove on South Island (Photo: R. Gaymer). 
37. Casuarina woodland a t  Anse Csdres ,  South Island. 
38. Coconut plantation, south end of West Island. 
39. Settlement on West Island. 
40. One of the rainwater tanks in the West Island settlement. 
41. Fishing shack on Middle Island, a t  Eas t  Channel. 
Chapter 1 
SCIENTIFIC STUDIES ON ALDABRA ATOLL 
D. K. Stoddart 
Department of Geography, Cambridge University 
1. 'The Ecology of Islands 
2. Previous Investigations 
3. Present  Investigations 
4. Acknowledgments 
Atoll Research Bulletin No. 118: pp. 1-8 November 15, 1967 
1. THE ECOLOGY OF ISLANDS 
Oceanic islands have been recognised since the time of Darwin and 
Wallace to be of special significance in the study of biogeography and evolu- 
tion. The work done in the past century, particularly in the Lesse r  Antilles, 
the Australasian archipelagoes, and the Hawaiian Islands, has permitted the 
formulation of general principles of dispersion, colonisation, a r~d  speciation 
in island biotas. By the time that these problems were being recognised, how- 
ever, and hypotheses were  being formed about them, many of the more ac- 
cessible and congenial islands were being newly settled hy man, with the 
resulting disruption of many unique assemblages of plants and animals by 
economic activities, o r  by the unexpected impact made hy introduced species. 
This has happened particularly on the more  accessible tropical islands, in 
many of which the opportunity to study undisturbed indigenous f lo ra s  and 
faunas has  gone for  ever. 
Much recent work on island ecology has, therefore, concentrated on those 
islands where disturbance has been minimal, particularly in the more  remote 
and hostile environments of the southern cold temperature zone (Holdgate and 
Wace 1961; Wace 1965) (for al l  references s e e  the "Bibliography of Aldahra", 
Chapter 6 of this Bulletin); on Amsterdam, Kerguelen, Crozet and St Paul in 
the southern Indian Ocean; on Macquarie, Auckland and Campbell Islands; and, 
in the south Atlantic, on Tristan da Cunha, Inaccessible and Gough Islands. 
Here the problems of insularity have been linked with that of the circumpolar 
distribution of many plants and animals (Pantin 1960; Darlington 1965). Within 
the tropics, classic  studies have been car r ied  out in the Galapagos Islands, 
initiated by Darwin himself and recently intensified since the opening of the 
Charles  Darwin Research Station there (Bowman 1966). Other islands, includ- 
ing some in low latitudes, have been studied for  the light they throw on the 
processes of replacement of native by introduced species, a s  in the case  of 
St Helena and Ascension in the Atlantic Ocean, and Clipperton in the Pacific. 
F rom these studies of islands, certain principles of island ecology emerge 
(Hesse and others  1951, 621-635; Darlington 1957, 476-544; Gulick 1932; 
Holdgate 1960; Carlquist 1965). First ,  islands a r e  isolated by the sea, which 
ac ts  a s  a bar r ie r  o r  f i l te r  of variable intensity for  different groups of plants 
and animals, and the degree of isolation is a function not only of distance but 
also of the time available for  colonisation: the older the island, the greater  
the probability that successful introduction has occurred. In this property of 
isolation we may include Wallace's distinction hetween oceanic and continental 
islands. Second, islands have limited area,  and hence carrying capacity, 
which for  la rger  animals may be l e s s  than a minimum threshold for  survival, 
and they also possess unique environmental characteristics, particularly in 
climate. Work s o  f a r  has concentrated on volcanic islands, such a s  the Tristan 
group, but coral  islands, with a narrower range of environments, have the 
advantage for  study of a s impler  biota. Third, the combination of a peculiar 
environment with the fact  that successful colonisation is dependent on a ca- 
pacity for  long-distance over-water dispersal and for  survival in new habitats 
means that the biota of islands tend to be smal l  and disharmonic. The absence 
of many continental genera and species means that competition is reduced, 
and island species may increase their ranges. Infrequent colonisation and pro- 
longed isolation favour the evolution of endemic varieties, species, and genera, 
especially on the older and la rger  islands such a s  Hawaii. Finally, the small- 
ness of the biota, and i t s  under-exploitation of the island environment, means 
that such communities a r e  often unstable and a r e  specially liable to large- 
scale disruption by invading alien plants and animals. This is well seen in the 
disappearance on many islands of la rge  breeding colonies of sea birds, and of 
such ungainly creatures as the dodo, which a r e  clearly unfitted to compete 
with introduced predatory mammals and competitors. 
The islands of the Indian Ocean include granitic islands, volcanic islands, 
sea-level coral reefs  and atolls, and islands formed of elevated reef lime- 
stones. Of the islands of coralline origin, the atolls have been studied in some 
detail a t  the beginning of the century, particularly in the Maldives (bibliog- 
raphy in Stoddart 1966, 107-122) and a t  Cocos-Keeling, on which Darwin 
worked and which has been studied more  recently by Gibson-Hill (bibliography 
in Sachet and Fosberg 1955). The elevated limestone island of Christmas, 
near Java, was monographed by Andrews in 1900, and has been studied since. 
The high islands of the Andamans and Nicobars, visited by Seymour Sewell, 
have attracted comparatively litt le attention by comparison with those of the 
western Indian Ocean. 
These latter,  hetween the African coast  and the approximate line of the 
mid-ocean ridge (Figure I), a r e  of considerable importance in the study of 
the geography and land ecology of islands. They include, besides the great  
landmass of Madagascar, the volcanic Mascarene Islands (Mauritius, Rod- 
riguez, Reunion), the granitic Seychelles, the coral  atolls extending from the 
Laccadives through the Maldives to the Chagos Archipelago, and the cluster  of 
reef islands, many of them elevated, to the north of Madagascar, f rom Aldabra 
to the Amirantes and the Seychelles Ridge. Our knowledge of the biogeography 
of this a r ea  derives largely from a s e r i e s  of expeditions led by Professor  
Stanley Gardiner in 1899-1900, 1905, and 1908-09, culminating in the Fauna 
and Geography of - the -Maldive and Laccadive Archipelagoes (Gardiner 1903-06) 
and in the eight volumes of Reports of the Percy  Sladen Trust  Expedition 
(Gardiner 1907-36). Since Gardiner's work, several  of the islands, particu- 
. . 
lar ly in the southwest Indian Ocean, have been devastated beyond the possi- 
bility of fur ther  useful work, mainly by guano diggers, and even when he wrote, 
many of the most interesting forms,  such as the giant flightless land birds of 
the Mascarene Islands and the giant land tortoises of the southwest Indian 
Ocean, had been hunted to extinction o r  near-extinction by man and his intro- 
duced predators. 
Of the elevated reef islands of the western Indian Ocean, only Aldabra has 
escaped massive interference by man. By contrast,  the guano r e se rves  of 
nearby Assumption have been mined fo r  many years, and this applies also to 
St P ier re ,  Astove and others  (Baker 1963, 110-127; review by Hutchinson 
1950; and Chapter 3 of this Bulletin). The lack of economically workable guano 
deposits on Aldabra, together with an environment unsuited to agriculture o r  
even to human settlement, has meant that here isolation has continued to the 
present day. 
The ecology of Aldabra is of interest  for  three main reasons. First ,  i t  is 
an uplifted atoll, and hence provides a wider range of habitats than most 
sea-level reef islands. Second, it is oceanic, in the sense that there is no evi- 
dence of any former land connections with continental areas, and hence the 
biota must have been derived by normal dispersal processes; but a t  the same 
time i ts  relative proximity to Africa, and particularly to Madagascar and the 
Comoros, means that the probability of successful colonisation from these 
sources has been high. Combined with the diversity of habitat, this has pro- 
duced a fauna and flora exceptionally rich for a coral atoll. And third, i t s  
isolation has not only led to the development of endemic species of both plants 
and animals, but has favoured the development o r  survival of such creatures 
a s  flightless land birds and the giant land tortoise. With the devastation of 
nearby islands which originally possessed very similar ecosystems, Aldabra 
is thus of special importance in the category of elevated coral atolls. Most of 
the similar high limestone islands in the Pacific have heen devastated for  guano 
(Ocean Island, Nauru, and Makatea being the worst examples), and those which 
remain (such a s  Henderson and Vostok) a r e  so far  from continental land as  to 
be biologically impoverished. Scientific understanding of elevated reef-lime- 
stone islands can thus only be obtained by detailed work on Aldabra Atoll, 
2. PREVIOUS INVESTIGATIONS 
Much early information on Aldabra was frankly speculative, and once i t  ap- 
peared in the literature i t  was repeated by many authors. Horsburgh, for 
example, states that "from the appearance of these islands, water is perhaps 
plentiful, and also timber of sufficient size to be useful to any ship in distress 
for  spars"  (Horsburgh 1852, 176). and according to Pridham (1846, 307) 
"water would appear to be plentiful". Opinions such as  these were clearly not 
based on any real  knowledge of the atoll. 
Table 1 l is ts  the scientific expeditions, official parties, and some of the 
more significant individuals to visit Aldabra since the f irst  hydrographic sur- 
vey in 1878. Of these investigations, four resulted in large collections of flora 
and fauna: those of Abbott in 1892, of Voeltzkow in 1895, of Dupont in 1906 and 
on several later occasions, and of Fryer  in 1908-09, in connection with Pro- 
fessor Gardiner's last expedition. The most important general memoirs a r e  
those of Voeltzkow (1897, 1902), Dupont (1907), and Fryer  (1911), and an out- 
line of the salient features of the ecology of Aldabra has been given by 
Stoddart and Wright (1967a). More detailed papers a r e  referred to in this 
Bulletin, and an attempt to give a complete bibliography is made in Chapter 6. 
Early voyages to Aldabra, with comments on the origin of the name, a r e  listed 
by Voeltzkow (1897, 40-41). 
In recent years, mention must he made of Ommanney's visit in 1948 and the 
popular account he later  wrote (Ommanney 1954); of the visit of the Calypso, 
Commander J.-Y. Cousteau, in 1954, which resulted in large additions to our 
knowledge of the birds, crustacea and Lepidoptera; and of the Bristol 
Seychelles Expedition in 1964-65. This party, led by M. J. Penny, visited 
Aldabra f irst  between 11 Novemher and 14 December 1964; a second visit was 
made by one member, R. Gaymer, between 4 October and 20 November 1965. 
5 
Table 1. --Previous Investigations at Aldabra 
Date Investigator Field of Study General Publication 
1878 July H.M.S. Fawn, Dr. Wharton Survey Wharton 1879, 1883 
1892 May H.M.S. Redbreast, General Fairfield, Griffith 
M r  T. R. Griffith and Abbott 1893 
1892 Sep- Dr W. L. Abbott Birds, insects, Abbott 1893 
Dec. plants 
1895 Mr Wilson Molluscs Van Martens and 
Wiegmann 1898 
1895 Apr- Dr A. Voeltzkow Geology; al l  Voeltzkow 1897, 
May groups 1902b 
1904 Dec. Mr  F. R. Mortimer Birds - 
1905 Anon. General Anon. 1920 
1906 May Valhalla, Lord Crawford Birds, insects Nicoll 1908, 114-123 
1906 Oct- Mr R. P. Dupont Plants, insects, Dupont 1907 
Nov. birds 
1907 Mr H. P. Thomasset Insects, birds - 
1908Aug.- M r  J. C. F. F r y e r  Geology; all  F r y e r  1910, 1911 
1909 Feb. groups 
1916 Mr W. Fox Botany Hemsley 1919 
1937 Oct. Mr  D. Vesey-FitzGerald Birds, vegeta- Vesey-FitzGerald 
tion 1940, 1941, 1942 
1948 Seychelles-Mauritius Commercial Ommanney 1952, 
Fisheries  Survey f i sher ies  258-294; 
Mr J. F. G. Wheeler Tur t les  Wheeler and 
Dr F. D. Ommanney Omrnanney 1953 
1953 Nov. Italian Zoological General; insects Prosper i  1955, 1956, 
Expedition: C. Prola, 1957; Berio 1956, 
F. Palombelli, 1959 
F. Prosperi,  S. Nievo 
Table  1. --(continued) 
Date Investisator Field of Study General Publication 
1954 May Calypso, J.-Y. Cousteau General, Cousteau 1959, 1963 
G. Cherbonnier crustacea 
birds 
1956 Mr W. Travis  Turbo Travis  1959, 157- 
193 
1957 Dec. Yale Seychelles Expedition General, 
Dr A. J. Kohn tortoises 
Dr W. D. Hartman 
1959 H.M.S. Leopard Birds Boulton 1960 
1959 Mr H. Legrand Lepidoptera Legrand 1965 
1960 Sep. Dr B. H. Baker, Geology Baker 1963 
1961 Jan. Mr  C. J. Piggott 
1962 Jan. H.M.S. 0 s  Birds Morr i s  1963 
1964 R. E. Honegger Birds, tortoises Honegger l966a. b 
1964 Mar. H.M.S. 0- Birds Bourne 1966 
1964 Nov.- Bristol Seychelles Birds, tortoises Blackman 1966 
Dec. Expedition: 
M. J. Penny, C.M. Penny, 
R. Gaymer, R. Blackman, 
P. G. Dawson 
1965 0ct.- R. Gaymer 
NOV. 
Birds, tortoises Gaymer 19661, 
1966 Sep.- Dr D. R. Stoddart Geomorphology, Stoddart and Wright, 
Oct. Dr C. A. Wright land ecology 1967a 
3. PRESENT INVESTIGATIONS 
Aldabra has recently been considered as a possible s i te  for  the construc- 
tion of a military airfield by the Ministry of Defence. With the co-operation of 
the then Minister of Defence fo r  the Royal A i r  Force, Lord Shackleton, and of 
the Hydrographer, Rear-Admiral G. S. Ritchie, i t  has been possible, with the 
support of the Southern Zone Research Committee of the Royal Society, to 
b2yin detailed investigation of the geography and land and mar ine  ecology of 
Aldabra, fo r  the purposes of preparing long-term conservation plans and of 
gaining knowledge of this unique island ecosystem. Dr C. A. Wright and the 
author were attached, in September and October 1966, to the British Broad- 
casting Corporation's Expedition Turtle, a s  a resul t  of which fur ther  investi- 
gations a r e  now being planned. This Bulletin has been designed to summarise 
present  knowledge of Aldabra, within the framework of the work carr ied out 
during the 1966 expedition. Chapter 2 covers the whole range of geography and 
ecology, so f a r  a s  is known. Chapter 3 summarises  the very scanty and often 
old information on the islands near  to Aldabra, to prov'de comparative data 
fo r  the assessment of the importance of Aldabra itseli. In Chapter 4 Mr C. W. 
Benson presents a full analysis of the birds of the atoll and the neighbowing 
islands, with special reference to the land birds, based on his own field ex- 
perience in the Comoro Islands and an exhaustive study of the collections 
made by Abbctt, Voeltzkow, Dupont and others. Chapter 5 presents  some oh- 
servations by Mr R. Gaymer, made during his two visits a s  a member of the 
Bristol Seychslles Expedition, on the natural history of the birds, again with 
reference to the land birds. Finally, Chapter 6 gives a full bibliography. It is 
intended that this account will not only stimulate scientific interest  in this 
too-much neglected atoll, but will s e r v e  a s  a working paper fo r  the project of 
further  investigations now being planned. 
F rom our knowledge of the biota, i t  is clear  that the importance of Aldabra 
s t ems  f i r s t  of all  f rom i t s  population of the giant land tortoise, a rel ic  of a 
once wider population which demands both urgent study and effective con- 
servation, and second, f rom the isolation of the atoll and the distinctive as- 
semblage of both plants and animals which has formed a s  a result.  Many 
species of both plants and animals may be distinct; and i t  was on such endemic 
species that scientific interest  a t  Aldabra, a s  indeed in most  insular biotas, 
formerly centered. Some of the endemics, such a s  the r a i l  Dryolimnas, last  
flightless bird of the Indian Ocean islands, a r e  of special concern, but their 
interest  is far  below that of the giant tortoises. More important from an 
ecological viewpoint a r e  the island populations of more widely ranging species, 
particularly the great  colonies of frigate birds and boobies, and the breeding 
populations of the migratory green turtle. Other species, while probably not 
distinct, no longer exist in la rge  numbers, and efforts must be made to pre- 
s e rve  them before they disappear: this  applies to the Sacred Ibis, and particu- 
lar ly to the Flamingo. 
With the possibility of military development, these problems immediately 
become acute: for  while we already know a grea t  deal about the composition 
of the biota, i n  the sense of l i s t s  of plants and animals, we know very litt le 
about the island ecology and i t s  a rea l  variation. Many ecological problems, 
such a s  those of food chains and population structure, cannot be adequately 
studied during brief visits. The realisation of the scope and importance of 
purely ecological problems, a s  opposed to taxonomic ones, coincides, further- 
more, with a changing emphasis in island biology, from the simple recognition 
of peculiar species to the study of the genetics of change in remote, insular 
populations (Carlquist 1966). Studies in population genetics again require de- 
tailed long-term work. It is not too much to say  that only now a r e  theoretical 
concepts becoming available which can enable us to understand structure, 
function, and change in island ecosystems, but by thls time few island ecosys- 
tems remain to be studied. 
The Royal Society, with the active assistance of the Ministry of Defence, 
and following a conference in London in January 1967 attended by many scien- 
tific and conservation organisations from Britain and the United States, is 
organising a programme of further  scientific work a t  Aldabra in 1967-68. The 
Royal Society Expedition t o  Aldabra 1967-68 will consist of three parts.  The 
f i r s t ,  in August and September 1967, during the dry season, will concentrate 
on further land reconnaissance, and on lagoon ecology. A resident party to 
ca r ry  out long-term studies of the s e a  bird colonies, of the land birds, of the 
lagoon biota, and of the tortoises and turtles, will remain on the atoll fo r  the 
second par t  of the expedition, from August 1967 to March 1968, some mem- 
he r s  spanning both wet and dry seasons. Finally, in January to March 1968, 
the third part  of the expedition, a wet-season party will concentrate on land 
f lora and vegetation and land zoology. By the end of this programme, enough 
data will have been gathered to serve  a s  a permanent record of an unspoiled 
oceanic island, and a s  a basis  for  meaningful conservation measures if mili- 
tary development takes place. If, on the other hand, military development is 
averted, then this scientific project will provide a base-line for  continuing 
studies of this remote and st i l l  largely unspoiled unique island ecosystem. 
4. ACKNOWLEDGMENTS 
Thanks a r e  due f i r s t  of al l  to  the Ministry of Defence, and to Lord Shackle- 
ton, former  Minister of Defence for  the Royal A i r  Force,  and Rear-Admiral 
G. S. Ritchie, Hydrographer, fo r  their active assistance and co-operation in 
making scientific participation in the 1966 expedition possible; to the British 
Broadcasting Corporation and the leader  of the expedition, Mr  A. Boswortb, 
for  giving D r  Wright and myself every facility and aid on Aldabra; and to the 
Royal Society for  their interest  and support. D r  Wright and I a r e  also grateful 
to Mr C. E. Loveridge, Ministry of Public Buildings and Works, Wing-Com- 
mander P. A. S. Thompson, Ministry of Defence, Mr G. Dawson, British 
Broadcasting Corporation, and other members  of the expedition for  their help 
and companionship in the field, and to the late  Professor  C. F. A. Pantin, 
F.R.S., fo r  his initial encouragement. We thank the Director of the Royal 
Botanic Gardens, Kew, Si r  George Taylor, for  the loan of equipment and for  
the identification of the botanical collections by members of his staff 
(Dr J. P. M. Brenan; and M r  Clayton, grasses ;  Miss Hooper, sedges; 
Dr Jar re t t ,  fern; and M r  Bullock, other groups). I am grateful to Professor  
H. C. Darby and the University of Cambridge for  temporary leave of absence 
fo r  par t  of the expedition. 
I am also grateful to Mr  C. W. Benson and M r  R. Gaymer for  their con- 
tributions to this Bulletin. M r  Gaymer, who visited Aldabra twice with the 
Bristol Seychelles Expedition, has very  generously allowed me to read his  
unpublished memoranda and papers  based on his  work during that expedition. 
Lady Joan Fryer ,  widow of the late  S i r  John Fryer ,  whose memoir  on Aldabra 
is st i l l  the most  useful account available, has very kindly loaned m e  S i r  John's 
manuscript journal and other papers to do with his  visit to Aldabra in 1908-09. 
I thank a lso  D r  F. R. Fosberg and D r  Marie-Helene Sachet for  their interesL 
and advice on the conservation of Aldabra during the last  several  years. 
Dr W. R. P. Bourne has read the whole manuscript of this Bulletin and has 
made many most useful suggestions. Other sections have been read  by D r  
F. C. F r a s e r  and Mr John Peake of the British Museum (Natural History) 
(Chapter 2); Dr F. R. Fosberg, Smithsonian Institution (Chapter 2); and 
Dr R. E. Moreau, Edward Grey Institute, Oxford, and Dr G. E. Watson, 
Smithsonian Institution (Chapter 4). 
M r  Daniel Labworth very kindly gave permission for the quotation of sec- 
tlons of the commercial lease  agreement f o r  Aldahra, signed in 1955, used in 
Chapter 2. 
Finally, I am grateful to M i s s  R. King, who drew the maps; Mr  R. Coe, 
who made the prints; and to Mr  R. Balmforth, who carr ied out a very great  
deal of Xerox work in connection with this  project. 
Chapter 2 
GEOGRAPHYANDECOLOGYOFALDABRAATOLL 
D. R. Stoddart 
Department of Geography, Cambridge University and 
C. A. Wright 
Department of Zoology, British Museum (Natural History) 
1. Location and Regional Setting 
2. Geomorphology and Geology 
1. Coastal morphology 
2. Surface morphology 
3. Origin of Aldabra Landforms 
3. Flora and Vegetation 
1. Mixed Scrub 
2. Pemphis Thicket 
3. Mangrove Communities 
4. Psammophilous Communities 
5. Man-induced Vegetation 
4. Terrestr ial  Fauna 
1. Mammals 
2. Birds 
3. Land Reptiles 
4. Insects 
5. Other Groups 
5. Marine Biota 
1. Turtles 
2. Other Groups 
6. Settlement, Exploitation, and Con- 
servation 
1. Human Settlement 
2. Introduced Animals and Plants 
3. Exploitation and Conservation 
7. A Note on Place Names 
Atoll Research Bulletin No. 118: pp. 11-52 November 15, 1967 
1. LOCATION AND REGIONAL SETTING 
Aldabra Atoll (latitude Y024'S., longitude 460201E.) lies 260 miles northwest 
of Madagascar and 400 miles from the East African mainland. With the adjacent 
islands of Assumption and Cosmoledo, i t  r i ses  a s  an isolated mountain in a basin 
2000-2500 fathoms deep, hounded to the west by the African coast, to the south 
hy Madagascar and the Comoros, and to the east  by the Farquhar and Amirantes 
Banks and the Seychelles-Mascarene Ridge. Farther  north, this basin has been 
shown to contain thick sequences of sedimentary rocks and to have a normal 
crustal  s t ructure (Francis and others  1966). The Seychelles-Mascarene Ridge, 
clearly defined by the 2000 fathom isobath (Figure I), appears to be of complex 
structure. The Seychelles Bank itself is underlain by Pre-Cambrian granite, 
which emerges to form the main islands (Baker and Miller 1963; Matthews and 
Davies 1966). Matthews believes, f rom geophysical evidence, that s imi lar  rocks, 
with later  basic dykes, a r e  found hetween the Seychelles Bank and the Saya de 
Malha Bank, and again underlying Cargados Carajos Shoals near  the southern 
end of the Ridge. Conversely, the Amirantes ridge, southwest of Seychelles, is 
Figure 1.--Location of Aldabra 
thought to consist of a coral  capping, l e s s  than 1 km thick, overlying a basaltic 
volcanic a r c  (Matthews and Davies 1966). The Saya de Malha Bank itself, near  
the middle of the mid-ocean ridge, is also thought to consist of volcanic rocks 
capped with coral  (Shor and Pollard 1963), and the islands of Mauritius and 
~ 6 u n i o n  a r e  themselves volcanic. South of Aldabra the Comoro group consists 
of a s e r i e s  of volcanoes of different ages (Guilcher and others  1965), and la rge  
a r e a s  of the Madagascar granites a r e  covered with volcanics. 
Little i s  know of the crustal  s t ruc ture  north of the Comoros, o r  between 
Aldabra and Farquhar and Madagascar and the Amirantes. The conclusions Of 
e a r l i e r  biologists, concerned with problems of distribution, calling for  isthmian 
links and drifting continents, a r e  no longer tenable. Although geophysical evi- 
dence is lacking, the isolated nature and considerable relief of the mounts of the 
Aldabra group, rising steeply from uniform depths of c. 2200 fathoms, together 
with the proximity of recent volcanoes in the Comoros, suggests a volcanic base- 
ment at undetermined depth beneath the islands. This interpretation is supported 
by the presence of fragmental basalts,  s imi lar  to rocks f rom Madagascar, as- 
sociated with foraminifera of Eocene-Oligocene age, from the slopes of Provi- 
dence, 300 miles east  of Aldabra, a t  a depth of 744 fathoms (Wiseman 1936), 
and by the s imi lar  trends of both the Aldabra and Comoro ridges. This may im- 
ply the former  existence of high volcanic islands, s imilar  to the Comoros, per- 
haps in the early Tertiary, a t  Aldabra, Assumption and Cosmoledo, and also a t  
Farquhar, Providence and St P ier re ,  and their transformation into atolls by 
Darwinian subsidence. 
Apart, therefore, from the Comoros, the volcanic Mascarene Islands, and 
the granitic Seychelles, the islands of this western sector  of the Indian Ocean 
a r e  of reef origin. They include ei ther  sand cays of reef debris  on sea-level 
reefs, a s  in the Amirantes, Cargados Carajos, and the Chagos Archipelago, o r  
islands formed of uplifted reef limestones, a s  a t  Aldabra, Astove, Assumption, 
St P ier re ,  Providence, Cosmoledo and Farquhar. Baker (1963) has described 
the geology of many of these sma l l e r  islands, and their distribution is shown in 
Figure 2. 
The date of uplift of the ra i sed  reef islands, including Aldabra, is unknown. 
Contrary to ear l ie r  ideas, based on Daly's hypothesis of Holocene high stands 
of sea-level, i t  has now been shown that many elevated reefs, formerly thought 
to be of post-glacial age, a r e  in fact Las t  Interglacial. Veeh (1965, 1966), using 
uranium-series radiometric dating techniques, has shown that elevated fringing 
reefs  at Mah6 and Prasl in in the Seychelles and a t  Gabriel Island, Mauritius, a t  
9, 6 and 2 metres respectively above present sea-level, have ages of 140, 140 
and 160 thousand years. Dates of low elevated reefs  from Hawaii, the Tuamotus, 
the Cook Islands, and western Australia (all  reported by Veeh 1965), and f rom 
Florida and the Bahamas (Osmond and others  1965; Broecker and Thurber 1965), 
a r e  al l  g rea ter  than 80,000 years ,  and cluster  round 130,000-150,000 years  B.P. 
This suggests that many elevated reefs  were formed during the Last Intergla- 
cial  and have emerged subsequently, perhaps eustatically. This simple picture 
must be complicated locally by earth movement, but i t  provides a tentative 
time-framework into which the elevated Aldabra group of islands may fit. The 
freshness of the raised reefs  a t  Aldabra itself suggests that the time-scale may 
he too long, and material has been collected fo r  radiometric dating. There is 
Figure 2.--Geology of Indian Ocean Is lands  
certainly no basis for  Travis 's statement (1959, 170) that the age of Aldabra 
is less  than 3,500 years. 
No climatic records a r e  available for  Aldabra, though a wartime station was 
established a t  Agalega, 450 miles to the east  (Newnham 1945). and another has 
been established a t  Tromelin. The period May-November is that of the South- 
eas t  Trades, and is dry; December-April, during the north-west monsoon, is a 
period of calms, oppressive weather, and rains. Estimates of total rainfall vary 
f rom 15 inches per  annum (Vesey-FitzGerald 1942, 1) to 90 inches. Dupont in 
1906-7 recorded 34 inches between October and January, with 25 inches during 
17 days in January alone, when the wet season had just begun (Dupont 1907, 18). 
The mean annual total may thus he of the order  of 50-60 inches. Mid-day tem- 
peratures a r e  generally 85-90?F., and night temperatures may fall to 70?F. 
Aldabra l ies  to the northwest of the Indian Ocean belt of tropical cyclones, but 
i t  is occasionally affected. Perhaps the closest on record i s  that of February 
1898, which passed over the atoll. Spurs (1892) mentions the defoliation and kill- 
ing of vegetation during cyclones, and F r y e r  (1908-9) describes mangroves de- 
foliated in 1907, but these must be r a r e  events. Other cyclones have passed 
close by the atoll in recent years ,  hut their  effects have not been recorded. 
2. GEOMORPHOLOGY AND GEOLOGY 
Aldabra Atoll (Figure 3) is an elevated atoll, elongated east-west, with a 
maximum length of 21 miles and a maximum width of 9 miles. Its total a rea ,  
bounded by the edge of the peripheral reef flat, is 141 square miles, and of this, 
land occupies 60 square miles. The land r i m  consists of four main islands (for 
a discussion of place names on Aldabra,seeSection 7 of this paper: the aster isk 
attached to names in this paragraph indicates the name used in this report): 
South Island*, also known a s  Main Island and Grande T e r r e  (42.5 sq. miles), 
Middle* o r  Malabar Island (10.2 sq. miles),  Polymnie* (0.7 sq. miles), and West 
Island* or Ile Picard (3.6 sq. miles). 
West Island and Polymnie a r e  separated by Main Channel*, 1000 yards wide 
and carrying 10-12 fathoms a t  i ts  entrance, and Middle and South Islands by the 
narrower East Channel* o r  Passe  Houareau. Both of these channels a r e  made 
dangerous for  navigation by rapid tidal currents, and East Channel in particular 
is shor t  and narrow. Main Channel branches dendritically lagoonward, and i t s  
branches maintain depths of up to 3-5 fathoms for  4 miles from i ts  mouth. 
Johnny Channel*, between Polymnie and Middle Islands, unlike Main and East 
Channels, is a gap in the land r i m  ra the r  than in the peripheral reef platform, 
which has been subsequently scoured out by tidal rips to a depth of 4 fathoms. 
West Channels* (Passe  Lanier), between West and SouthIslands, a r e  shallow 
gaps of  recent origin eroded through a narrow sector  of the land rim; they do 
not transect the reef platform. Of the West Channels, severa l  of the individual 
passes  between the small  residual islands arenamed(Passes  Femme*, Dubois*, 
Magnan*, Grabeau*); Passe  Dubois is the deepest and is navigable by sma l l  
c raf t  and pirogues a t  high water. 
In addition to the main r i m  islands, there a r e  numbers of smal le r  islands 
within the lagoon, mostly close to the land r im  and often connected to i t  a t  low 
water. These lagoon islands a r e  concentrated along the south shore of Middle 
Island and along the eastern lagoon s h o r e  of South Island. Within the lagoon it- 
self  there a r e  only two large islands: Ile Esprit* o r  Euphrates Island (0.13 sq. 
miles), with i t s  tiny adjacent Ile Sylvestre* in the west, and Ile Michel* o r  
Coconut Island, 0.16 sq. miles, in the east. The lagoon itself is shallow, and 
navigability depends entirely on the s ta te  of the tide. This has a maximum range 
of approximately 11 feet and is semi-diurnal: a t  low water springs, much of the 
eas tern  part  of the lagoon, together with a fringe along i t s  southern side, dr ies  
out, exposing mud flats and sandbanks; over  the rest ,  Admiralty Chart 718 plots 
soundings of not more than 1 fathom in  the inter-distributary a r e a s  of inner 
Main Channel. Because of the large a r e a  of the lagoon and the smal l  and re-  
s tr icted entrances, there is a considerable lag in tidal behaviour within the 
lagoon compared with outside it: a t  spr ings  the tide is st i l l  flooding in the Bras 
Takamaka* when i t  has begun to ebb outside. 
1. Coastal Morphology 
(a) Seaward side 
The land r im  is surrounded on i ts  seawardside by . n intertidal o r  slightly 
subtidal platform, which is narrowest (down to 100 yards) on the east  o r  wind- 
ward side, averages 200-300 yards in width along the north and south coasts, 
Figure 3.--Aldabra Atoll 
and reaches 500 yards on the shel tered west coast. According to Travis (1959, 
163), the reef front falls gently f rom the edge of this platform to a depth of 70 
feet, before falling steeply to great  depths, and this upper slope is marked by 
furrows 2 feet wide and 1 foot deep. The upper seaward slope may thus be equiv- 
alent to the 10 fathom t e r r ace  identified on many other atolls. Depths grea ter  
than 100 fathoms a r e  generally found within half a mile of the edge of the inter- 
tidal platform, except a t  the eas t  end, off Point Hodoul, where a shelf of bare  
limestone and algae extends seawards fo r  two o r  three miles with depths of 20- 
25 fathoms (Travis 1959, 163). 
The intertidal platform itself is an erosional feature formed of planed reef- 
rock with a thin, discontinuous sand cover and mats of Cymodocea, and is not a 
primary reef flat formed by contemporary reef growth. The seaward edge is 
marked by an intermittent boulder zone on thewindward side (Plate 3), hut there  
is no algal ridge, in contrast to the r ee f s  of the central  Indian Ocean (Stoddart 
1966, 17). Baker (1963, 110) has argued that the platform is a growth feature, 
s ince i f  i t  were  erosional i t  would be widest in more exposed locations. This 
misconceives the erosional process, however, which is mainly solutional and 
biological, rather  than abrasional, and hence not s o  directly dependent on wave 
energy. His second point, that i t  must  bea  growth feature because i t  continues 
into the channel entrances, does not follow. Theplaned-rock surface cannot be 
a simple growth feature, nor could i t  f o rm by reef growth a t  i t s  present level, 
which dr ies  a t  low water springs. No living corals  were  seen on the flat between 
East Channel and Anse Ckdres, nor a t  the seaward side of West Island. F r y e r  
(1911, 413-414) suggested an erosional origin, and this is supported here. There  
is no information on reef growth on the seaward slope, though reef-blocks and 
cobbles suggest that Heliopora is important. 
The inner margin of the intertidal flat orplatform is generally formed by 
low retreat ing limestone cliffs in which corals  a r e  exposed. The cliffs r i s e  to 
15 feet above the platform in the eas t  of the atoll, and to slightly lower in the 
west. Two distinct cliff morphologies may be recognised, the exposed type and 
the medium-energy type: 
(i) Exposed Type 
Locality: seaward coast f rom Takamaka to Point Hodoul. Here  the cliff 
form is indistinct and ramp-like, rising a t  a high angle f rom a narrow basal 
intertidal platform with r immed pools (Plate 1). The main peripheral reef 
platform appears to be a t  a lower level he re  than elsewhere, and su rge  
breaks over the rimmed-pool platform, which is less than 3 yards wide and 
is coloured reddish-brown with algae. The upper par t  of the cliff-ramp is 
deeply and intricately dissected by salt-spray solution holes. There a r e  no 
beaches. This type is homologous with severa l  exposedshore profiles under 
study on elevated reefs  of the southwest Pacific. 
(ii) Medium-energy Type 
Locality: Point Hodoul to East Channel, and the north coast  of Middle 
Island. Here sea  conditions a r e  less extreme, and the dominant process is 
solutional: the cliff is vertical, deeply undercut by an intertidal solution 
notch, and the intertidal rimmed-pool platform is absent (Plate 2). The 
notch has an amplitude a t  i ts  mouth of not l e s s  than six feet; and the deepest 
notches extend back under the cliff fo r  up to 30 feet. Small sand and cobble 
beaches may fo rm within these deep notches, and a r e  characteristically 
blue-coloured f rom their Heliopora content. Water constantly drips f rom 
the notch roof, where deposition may be taking place. Above the notch the 
cliff face r i s e s  vertically for  6-9 feet, and a t  the curve-over to the land 
surface i t  is intricately dissected by salt-spray solutioncups. Occasional 
blowholes connect the land surface with the deeper notches. While the 
notch-forming process is clearly chemical and biological ra ther  than 
mechanical, and analogous to that described f rom the Red Sea by Macfadyen 
(1930) and Guilcher (1955). the undercutting frequently leads to failure and 
collapse of sections of the cliff face. Inplan, the recession process forms 
micro-headlands and bays, but the outline is surprisingly regular  and out- 
l ie rs  and residuals a r e  ra re .  Immediately a t  the base of the cliff, between 
the notch and the intertidal platform, there is often a linear depression 
which may be up to 2 feet lower than the platform itself. This is probably 
partly excavated by mechanical action, and partly by increased solution 
associated with turbulence, a t  t imes of high water; a t  low water springs 
the notch is completely exposed, and a t  high water springs the s e a  reaches 
i ts  upper lip. 
Beaches a r e  ra re .  In places, uneven cliff-retreat has formed smal l  coves 
with "pocket heaches" (Plate 4), locally known as- (the "lances" of F rye r  
1911, 402). At Anse ~ h d r e s  (Plate 5) the beach is less than 100 yards long, with 
a 100 slope, and a low-water width of 50 yards. Half the beach is lined with 
beachrock outcropping at high water level. Similar pocket beaches a r e  reported 
on the south coast of Aux Vacoas, Trou Nenez and Anse Quive, but have not been 
visited: i t  is possible that a t  some of these locations the sand is s o  extensive 
that locally it covers the cliffs and joins the beach to the dunes above. At the 
eas t  end of South Island, smal l  perched beaches up to 3 feet in thickness a r e  
found on the cliff-top 15-20 yards inland fromthe edge (Plate  4). These a r e  
clearly s torm deposits with much Halimeda. On the leeward side of the atoll, 
beaches a r e  more extensive, as a t  Anse Mais, Anse Badamier, and Anse 
Anglais; and along the southernmost mile of the seaward coast  of West Island 
beach deposits almost completely blanket the underlying ra ised  reefrock 
(Plate 38). At the settlement itself the beach r i ses  to a height of 15 feet above 
the intertidal platform, and has basal beachrock severa l  hundred yards long and 
severa l  yards wide. 
Dunes a r e  developed along much of the south coast of South Island, f rom 
Point Hodoul westwards. Between Point Hodoul and Takamaka the dunes a r e  
narrow and low, only locally exceeding 6 feet in thickness (Plates  6-8); further 
west, a t  Grand Trimeau, Dune dtMesse, Dune Patates and Dune Jean Louis, 
isolated dunes r i s e  to heights of 50 feet above sea  level, and a r e  visible from 
the lagoon. Small dunes up to 13 feethigh a r e  also found a t  the south end of West 
Island (Plate 9). 
(b) Lagoon side 
The lagoon shores  a r e  formed either of undercut reef limestone o r  by man- 
grove communities; the lat ter  a r e  discussed in Section 3(3). The undercut cliffs 
of the lagoon shore  differ from seaward medium-energy cliffs mainly in their 
lower total height. The vertical amplitude of the solution notch is approximately 
the same (6-8 feet), but the vertical cliff above is rare ly  more than 1.5 feet and 
in many cases  i t  is s o  low that it is overtopped by the s e a  a t  highest high water. 
The deep undercutting of the cliffs i s  striking (Plate  10). The width of the basal 
erosion platform formed by cliff recession i s  variable, but may reach 50 yards; it 
i s  generally a bare rock platform, with solution grooves normal to the shore, oc- 
casional residuals (which because of the ca lmerwaters ,  especially a t  the eas t  end 
of the lagoon, may be of most delicate form),  and sma l l  patchy beaches a t  i t s  
landward margin. Active recession has isolated many s tacksfp la te  ll), of which 
the larger  ones a r e  vegetated. Several of these have surface dimensions severa l  
times a s  la rge  a s  the pillar on which they res t ,  and i t  is to these that the te rm 
"champignon" (mushroom rock) originally referred.  Undercut islands a r e  well 
seen in both Main and East Channels, alongthe north shore  of South Island, and 
particularly in West Channels, where the land r i m  has fragmented to form a 
se r i e s  of smal l  islands. Though both Wharton (1878) and Fryer  (1911) argued 
that much of the lagoon cliff recession was caused by the mechanical and chem- 
ical action of mangrove roots, i t  is more  likely that the undercuts are formed 
by a combination of physicochemical and biogenic (algal and molluscan) activi- 
ties. Fryer ,  however, is clearly correct  when he states  that the lagoon is ac- 
tively enlarging a t  the expense of the land. 
Much of the lagoon floor is covered with a thin layer  of calcium carbonate 
mud, overlying an irregular  rock floor. Shoals of calcium carbonate sand a r e  
exposed during low tides. Living cora ls  a r e  confined to the neighbourhood of 
West and East Channels, but a r e  s ca rce  elsewhere. Air photographs indicate 
a watershed between the Main and East Channels, a s  shown by bottom sediment 
patterns, 4-5 miles  west of the latter. 
2. Surface Morphology 
(a) Geneva1 featuves 
The main features of the surface geomorphology of Aldabra have been de- 
scribed by F rye r  (1911, 401-4051, when the local t e rms  "champignon" and 
"platin" entered the reef literature. The distinction between the two tends to 
oversimplify the morphological variations. It is clear  that two distinct s e t s  of 
factors, lithology and process, have influenced the development of the present 
landforms. Champignon is used for  deeply pitted and irregular  solution-fretted 
reefrock, and platin for  smooth surfaced, pavement-like cemented limestones. 
Champignon (Figure 4) occupies the greater  par t  of West, Polymnie and Middle 
Islands, together with most of South Island f rom West Channels to 1.5 miles  ea s t  
of Dune Jean Louis. It forms a zone severa l  hundred yards wide round the east- 
ern end of South Island, and near East Channel occupies the whole width of the 
island. Platin, apart  from small a r e a s  near  the settlement on West Island, occu- 
pies the greater  part of the eastern end of South Island, from Takamaka towards 
East Channel. It covers a total a r ea  of 14 square  miles, 28 per  cent of the dry 
land a rea  (excluding mangrove), o r  one quar ter  of the total land area. Champig- 
non forms the higher parts  of the atoll r im,  generally r is ing to 10-15 feet above 
Johnny Eosi 
ck!!A:.9;"..) &FyMNIE channel C---_ 
WEST 
I S L A N D  
(PICARD) 
i 
EMENIJ DRAINING TO 
DRAINING 10 EAST C H A N N E L  . 
M A I N  CHANNEL  
. ILES MOUSTIQUE 
, 
BQ Growing coroi R e e l  0 Sand ond Dunes 
@ C C I S U ~ ~ I " ~  
M o n g r o v e  ln iond  Cnamp ignon  
I M I L E S  5 Unvegetated Champignon [m c o o s t a l  Pemphls-  I d o m ~ n o t e d  Champignon I 
R I  
FIG 4 M A J O R  HABITATS OF A L D A B R A  ATOLL 
Figure 4.--Major Habitats of Aldabra Atoll 
mean s e a  level; the platin is lower, and ranges from approximately 3-10 feet 
above mean sea  level. 
(b) Suvface solution features 
The nature of champignon dissection varies  considerably in scale and origin, 
though no descriptive terminology exists  for  the resulting forms. The largest  
erosional features a r e  tidal solution holes excavated to intertidal levels, tens 
o r  occasionally hundreds of yards in extent, and which a r e  clearly expanding 
by solutional recession and undercutting of the marginal cliffs, exactly a s  on 
protected lagoon shores. These holes may dry completely a t  low water, hut flood 
rapidly on the rising tide. They are normally close to the s e a  o r  the lagoon, but 
we have no information on tidal lag. The mollusc fauna is marine, and the floors 
of the holes a r e  covered with soft  sediment. Good examples were  seen south- 
eas t  of the West Island settlement a t  Basin Cabris, and west of Point Hodoul. 
In the lat ter  (Plate 21), severa l  smal l  residuals have been isolated in the middle 
of the hole by the rapid recession of the margins. 
Normal champignon sinkholes a r e  on a smal le r  scale. They a r e  vertical 
clefts,  often in the centre of widersurfacedepressions, and in many cases  he- 
come wider with depth. Their mouths a r e  usually less than 15 feet wide, and 
their depth appears to be a function of the height of the land surface above s e a  
level. The deepest seen on South Island, in a r e a s  of high champignon perhaps 15 
feet  above s e a  level, were 12-15 feet deep. Though i t  was the dry season, most 
had standing water, with a brackish-water molluscan fauna. The dry sinkholes 
have a bottom full of yellow-brown s i l t  andclayey sediment. There is no evi- 
dence of the solutional undercutting characteris t ic  of marine tidal solution, but 
the walls a r e  vertically furrowed by freshwater solution. 
The third level of dissection in champignon is that of pinnacle and pothole' 
formation on the surface,  which gives champignon i t s  distinctiveness. The most 
extreme and intricate pinnacle formation is found in the salt-spray zone on top 
of seaward cliffs, where holes and pinnacles a r e  angled slightly seawards. The 
bottoms of the holes a r e  round in plan, and flat, and a t  lower levels contain sa l t  
water. They are s imi lar  to salt-spray solution features described, for example, 
f rom Puerto Rico by Kaye (1959). and seenon many of the Solomon Islands, par- 
ticularly on New Georgia. Away from the salt-spray zone, in a r eas  where su r -  
face solution is by fresh water, the dissection is less  extreme. In the most dis- 
sected salt-spray champignon the holes and pinnacles may have a vertical 
amplitude of more than 1 foot, with comparable diameters; in the freshwater 
zone this is infrequent, and the surface dissection grades towards a broken 
scoriaceous o r  honeycomb character.  Champignon is generally devoid of sur- 
face soil,  except for  thin sandy deposits on the floors of some potholes (Plate  
13). 
Solutional processes on platin operate on two levels. Though gradients a r e  
gentle, the platin has a local relief of up to 6 feet, and the sur face  consists of 
many local surface-drainage basins centred on solution pans. Many of these 
'The t e r m  'pothole' i s  usually used fo r  mechanically-scoured features formed by fluvial 
action (Baulig 1956, 106); the term a s  used he re  i s  synonymous with 'solution cup' and i s  used 
descriptively (Baulig 1956, 61-62). 
dry out during the dry season (P!ate 27), and even the largest a r e  considerably 
reduced in size (Plate 24). Flamingo Pool, the largest, has a dry season 
diameter of about 200 yards. All a r e  freshwater, a s  shown by their molluscan 
and crustacean microfauna; and it is clear that during the wet season these pools 
expand, some perhaps coalesce, and large areas of platin a r e  covered by up to 
2 feet of water. This is demonstrated by the solutional undercutting of limestone 
residuals between the pools, and by the distribution of shells of the freshwater 
mollusc Bulinus, found 1.5-2 feet above the general platin surface, lodged on 
limestone residuals. The gross topography of surface dimpling associated with 
these pools is probably solutional, though solution may be a discontinuous proc- 
ess. Several pools, during the dry season, a r e  surrounded by ramps of mam- 
millate limestone, samples of which show depositional layering. Clearly solu- 
tion during the rains is followed by marginal deposition a s  pools dry out. Most 
of the surface drainage is local and unintegrated; only near Cinq Cases is there 
any sign of a short, semi-permanent drainage line leading to a central sink 
(Plate 23), though such features may be more widespread during the wet sea- 
son. 
The second platin solution process is small-scale and local. In areas  of flat 
surface, lacking drainage systems, rainwater may stand for days after falling. 
By processes not yet studied, these rainwater pools a r e  able to etch the lime- 
stone surface by solution, and gradually become incised, and bounded by cliff- 
lets showing pronounced basal solution-notching (Plate 16). Most of these in- 
cised pools a r e  not more than 6 inches deep, though the deepest was more than 
1 foot, and most a r e  a few yards in maximum dimension. The floors a r e  abso- 
lutely smooth, thinly-coated with a film of cream-coloured sediment, and 
strongly contrasting with the rougher grey surface of the interpool areas. The 
striking flatness of the platin results partly from the final smoothing by this 
process of the dimpled surface formed by the main solution pans (Plate 15). 
3. Origin of Aldabra Landforms 
Fryer (1911, 405-407) distinguished three main rock-types a t  Aldabra: the 
peripheral elevated reef, exposed in the sea cliffs; the champignon rock, which 
he termed a metamorphosed limestone; and the platin, which he considered a 
detrital limestone. He noted the abundance of reef corals in the position of 
growth in the sea cliffs, and deduced that these constituted an uplifted atoll reef. 
He drew attention to the freshness of many of the corals: on the surface near 
the cliffs there a r e  many beautifully preserved Tridacna shells in the position 
of growth, with open valves, which, with the corals, suggests a relatively re-  
cent date for  the emergence. The platin rock he considered to be a back-reef 
deposit, mainly of clastic sediments with molluscs and foraminifera, formed 
a s  a reef-flat deposit in the lee of the eastern reef and subsequently uplifted 
with it. The distinction between the elevated reefrockand the champignon rock 
was less clear, and Fryer considered the champignon rock to be a phosphatised 
reefrock. In Fryer's view, the morphology of Aldabra is the result of relatively 
minor solutional modification of a reef topography formed before the elevation 
of the atoll, and this interpretation superseded Voeltzkow's (1902a) thesis, in- 
fluenced by Murray's theory of atoll formation, which laid s t r e ss  on the uplift 
of a bank of deeper-water foraminifera coated by corals. 
Fryer ' s  interpretation neglects severa l  geomorphic features which indicate 
a more complex history, a s  F rye r  himself realised in his account of Ile Espri t  
(1911, 407-408). The platinsurface of South Island is not simply a slightly 
modified depositional surface, but has  undergone considerable vertical erosion. 
.,. . 
Following uplift of both platin and champignon, vertical solution holes a r e  
formed, and fine brown residual sediment is washedinto them and ultimately 
lithifies. This brown pipe-limestone is much more resistant to solutional ero-  
sion than the surrounding white limestone, especially in the platin, and i t  
weathers out to form stacks o r  pi l lars  on retreating cliffy coasts, where i t  is 
morphologically identical with s imi l a r  pipe-limestones studied in the British 
Solomon Islands. The pipe-limestones a r e  also exposed by vertical erosion, and 
the f lat  surface of the platin is interruptedby massive irregular  blocks of 
brown pipe-limestone 3-6 feet high, and in some cases  6-9 feet in diameter 
(Plates  18 and 19). The surfaces of the residuals a r e  furrowed by solution 
lapies, and near the freshwater pools they may be solutionally undercut. With 
the open vegetation, the resemblance of the pillars to termite mounds gives the 
platin landscape a distinctly African savanna landscape appearance. 
The residuals show that in spi te  of the flatness of the platin surface, the 
main platin sur face  is erosional, and the originalsurface must have been a t  
least  6 feet  higher and probably more. Over much of the platin, this would bring 
i t  c loser  to the level of theperipheral champignon. The residuals themselves 
must be distinguished from isolated patches of champignon within the platin 
area:  these may stand up to 5 feet  above the general platin surface, and have 
a typically scoriaceous surface. They a r e  interpreted a s  patch reefs  on the 
fo rmer  reef flat, and demonstrate the original topography was itself irregular.  
Since the solution of these isolated champignon patches is purely by f resh  water,  
their  dissection i s  l e s s  extreme than on the coastal champignon. 
The character  of the platin sur face  is highly variable, with facies changes 
in the back-reef deposits. Generally the sur face  is strongly lithified, and 
weathering is taking place by spalling o r  exfoliation of large but thin s labs of 
rock, which ring musically when walked over (Plates 15 and 17). This process,  
which is more characteristic of igneous rocks, has also been observed a t  
Rangiroa Atoll, Tuamotu Archipelago (Stoddart, in press) ,  and in the northern 
Marshall Islands (F. R. Fosberg, personal communication), but the processes 
causing i t  a r e  not fully understood. At another location on the platin, where the 
superficial deposits contained mar ine  molluscs, i t  was found that these were  
weathering out of a loosely cemented coquina. It should ultimately be possible to 
map these facies zones in the back-reef area. 
If the hypothesis of a t  least  s ix  feet of vertical downwearing is accepted, 
certain difficulties remain. The flatness of the platin surface and i t s  level above 
mean sea-level a r e  problems. It is a lso  implied that in the past solutional 
downwearing has proceeded rapidly on platin, though a t  present these processes 
a r e  slow, and in places deposition is taking place; whereas on the champignon, 
which is the a rea  of deepest and most  intricate dissection, i t  is argued that 
least  downwearing has occurred. Complete explanation of these anomalies is not 
yet possible. In the case  of the platin, we need to know the relationship between 
i t s  near-equilibrium surface and tidal levels. In the case  of the champignon, i t  
is known that f r e sh  rock exposures a r e  less  resis tant  than older ones, and i t  
may be suggested that the most intricate dissection of champignon takes place 
rapidly after exposure, and that case-hardening then decreases the ra te  of solu- 
tion and protects the surface. 
Fryer  himself emphasised the anomalous character of Ile Esprit, in the 
lagoon. Here a complex topography of pinnacles and depressions with a verti- 
cal relief of up to 18 feet resembles in miniature a tropical Kegelkarst (Plate 
14). The central part of the island is formed by a relatively undissected ridge 
rising to more than 30 feet. The island is composed of shelly limestone over- 
lain by cemented limesands, with vitreous brown cavity fills. Fryer interpreted 
the whole a s  a lithified homologue of the soft sediments in the large tidal solu- 
tion basin on West Island, the implication being that the reefrock surrounding 
these pan sediments, to a height equal toat  least that of the highest part of the 
island (30 feet), has been eroded away. Comparison of the shell limestone and 
limesands, with the vitreous cavity fill, which Baker (1963, 109) found to have a 
phosphate content of 35-40 per cent, and the normal pipe-limestone of other 
parts of the atoll does not convince that they have a similar origin. The height 
of the Esprit ridge, approximately 15 feet higher than any other solid rock on 
the atoll, requires explanation. It is possible that the original uplift of the atoll 
was not l e s s  than 30 feet, and that Esprit i s  the last remnant of a widespread 
lagoon fill; but in this case the horizontal bevelling of the marginal cliff tops a t  
about 15 feet presents an additional problem. 
While in detail the morphology of the raised reefs is complex, therefore, 
and their history incompletely known, the two major controls a r e  seen to be 
lithology and type of solution. The elevated coral limestones, with their coarse 
honeycombed structure and high permeability, lend themselves to deep and in- 
tricate dissection and the formation of sinkholes which may coalesce to form 
larger  features. The fact that champignon dissection is most extreme near the 
sea  indicates that salt spray is a powerfulagent of solution. In the finer-grained, 
less permeable, back-reef deposits forming the platin, the original honeycomb 
structure is absent, and the solutional depressions formed by fresh water a r e  
broad, shallow features. Where patch reefs formerly existed on the platin, how- 
ever, a modified form of champignon surface is formed, with freshwater solu- 
tion giving a scoriaceous surface rather than deep honeycombing. 
The land area  is actively decreasing, by retreat of both the seaward and 
lagoon cliffs, forming wider seaward intertidal platforms anda larger lagoon. 
By measuring the rate of solution retreat  of the cliffs, it should be possible to 
calculate the ra te  of formation of the seaward intertidal platform. Assuming 
(a)  a mean width of 200 yards for the platform, and (b) a period of 5,000 years 
since sea-level reached i ts  present level in the Holocene, suggests a ra te  of 
seaward cliff retreat of 1 yard in 25 years, if the platform is formed by cliff 
retreat wholly in the Post-glacial. This ra te  is probably excessive in view of 
the measured rates of notch formation, averaging 1 mm per annum, in other 
parts of the world: Aldabra would form an excellent location for field studies of 
limestone solution rates. 
3. FLORA AND VEGETATION 
The f i rs t  botanical collecting a t  Aldabra was that of Abbott in 1892 (Baker 
1894). Voeltzkow's collections made in 1895 were studied by Schinz (1897; also 
Voeltzkow 1902b). Further collections were made and reported by Dupont 
(1907, 34-41, and later), by which t ime at  least 100 species of flowering plants 
had been recorded. Fryer's account (1911, 414-416) includes the f i rs t  detailed 
ecological notes, and his collections, together with thoseof W. Fox, who visited 
Aldabra in 1916, were worked up, with a l l the  earl ier  material, in W. B. 
Hemsley's "Flora of Aldabra" (1919; also Hemsley 1916, 1917), which remains 
the standard reference. Christensen (1912) noted a angle pteridophyte; and 
Vesey-FitzGerald (1942) added useful ecological notes on thevegetation. A 
further collection of 55 numbers, including 45 species, was made in 1966 and 
has been identified at Kew. 
The flora is thus relatively well known. Hemsley'sflora contains 173 species 
of flowering plants recorded f rom Aldabra, together with a number of common 
atoll species recorded from nearby islands, which might also be expected to 
occur at  Aldabra, but which had not then been collected there; a few additional 
records were obtained in 1966. Of this total he considered 68 to be indigenous, 
in the sense  of not being artificially introduced by man; and this compares with 
figures for  the indigenous floras of the Chagos Archipelago of 49 species and 
the Maldive Islands of 87 species. Of the 68 species, Hemsely considered 18 to 
he endemic to Aldabra itself (forming about 10 per cent of the total flora), and 
13 to be confined to the Aldabra group (Assumption, Cosmoledo, Astove, 
St Pierre,  Gloriosa). Of the rest,  18 species a r e  Madagascan, and 11 a r e  East 
African; and the flora is thus clearly related to that of the nearby continental 
areas. Table 2 lists the str ict  endemicsandTable 3 the group endemics re- 
corded by Hemsely (1919); no attempt bas been made to revise nomenclature. 
Table 2. Endemic species in the .- Aldabra flora 
Capparidaceae Rubiaceae 
Maerua dupontii Hemsl. Oldenlandia sp. n. 7 Hemsl. 
Tricalysia cuneifolia Baker 
Tiliaceae Pavetta supra-axillaris Hemsl. 
Grewia aldabrensis Baker Compositae Grewia salicifolia Schinz 
-- Vernonia aldabrensis Hemsl. 
Erythroxylaceae Plumbaginaceae Erythroxylon acranthum Hemsl. Plumbago parvifolia Hemsl. 
-- 
Ocbnaceae Oleaceae 
Ochna f ryer i  Hemsl. 
---
Jasminum aldabrense Hemsl. 
Tephrosia aldabrensis J. R. 
Drum. a d  Hemsl. 
~p te rdnrha  oligomeroides 
C. H. Wright 
Loranthaceae 
Leguminosae - Caesalpinioideae Loranthus aldabrensis Turri l l  
Cassia aldabrensis Hemsl. 
Euphorbiaceae 
Leguminosae - Mimosoideae Phyllanthus cheloniphorbe Hutch. 
Pithecelobium ambiguum Hemsl. Acalypha f rye r i  Hutch. 
Table 3. Group endemics in the Aldabra flora 
Capparidaceae Verhenaceae 
Cleome strigosa Oliv. Nesogenes dupontii Hemsl. 
-- 
Clerodendron minutiflorum Baker 
Icacinaceae 
Apodytes mauritiana Planch. Euuhorbiaceae 
Plumbaginaceae 
Plumbago aphylla Bojer 
--- -- 
Euphorbia abbottii Baker 
Acalypha claoxyloides Hutch. 
Asclepiadaceae Moraceae 
Secamone fryeri  Hemsl. 
-
Ficus aldabrensis Baker 
Solanaceae Dioscoreaceae 
Solanum aldabrense C. 1%. Wright Dioscorea nesiotis Hemsl. 
--
Acanthaceae Liliaceae 
Hypoestes aldahrensis Baker 
--- 
Asparagus umbellulatus Sieber 
Less is known, however, of the distribution and ecology of the vegetation, 
apart from the broad outlines sketched by Fryer (1911), followed by Hemsley 
(19191, and amplified by Vesey-FitzGerald (1942). Vesey-FitzGerald dis- 
tinguishes four vegetation types: 
1. Mixed scrub (Fryer's open bush); 
2. Pemphis thicket (Fryer 's  Pemphis bush); 
3. Mangrove communities; and 
4. Psammophilous associations (Fryer's shore zone); 
to which a further category may he added, 
5. Man-induced vegetation. 
These vegetation types a r e  closely associated with the morphological zones 
defined in  Section 2(2). Mixed Scrub is found on platin, Pemphis thicket on 
champignon, psammophilous associations on beaches, dunes and coastal cliffs, 
and the mangrove communities on the lagoon margins. The species-composi- 
tion of each type is known only imperfectly, however, and there is little infor- 
mation on internal variation within the types. Analysis is made more difficult 
by the lack of activity during the dry season, when many trees in the Mixed 
Scrub lose their leaves, and few plants a re in  flower anywhere on the atoll. 
This was the situation during the 1966 expedition. By contrast, flowering is 
reported to be rapid and widespread at theonset of the rainy season, in January, 
when more collecting needs to be done. 
1. Mixed Scrub 
The Mixed Scrub is especially variahle, both in floristic composition and in 
density. At the eas t  end of South Island, the scrub  is most dense on isolated 
patches of scoriaceous champignon, and more open on the platin, particularly 
+. near the freshwater pools (Plates  15-18). A numherof species, including 
Euphorbia abhottii and Thespesia populnea, appear to vary in frequency in dif- 
-- 
ferent  a r eas ,  but the most conspicuous segregation is that of the screwpine, 
Pandanus vandermeeschii, a t  pool margins (Plate 24). Though most of the t r ee s  
in the Mixed Scruh a r e  slender and shrublike, and l e s s  than 15 feet tall, the 
denser scruh  i s  very difficult to penetrate and is devoid of directional indica- 
tors: when i t  is possible to climb alow tree,  the pandans are  excellent indi- 
cators  of the location of freshwater  pools. In t e rms  of normal atoll floras, i t  is 
the Mixed Scrub which has the most unusual and African aspect, and many ex- 
pected atoll species a r e  absent, or ,  a s  in the case  of the leafless vine Cassytha 
filiformis, ra re .  Taller t r ee s  a r e  found only occasionally, and the massive 
-- 
Ficus and Calophyllum at the Takamaka pool a r e  best known (PIate 22). On the 
more open platin the orange-tinged sedge Fimbristylis spathacea fo rms  an 
irregular  tortoise-cropped turf (Plate 16), with small  brittle roset tes  of 
Eragrost is  sp. on hare rock in between. In addition to the sedges, the tortoises 
also crop the lower leaves of shrubs up to a maximum height of about 4 feet. 
Other g ra s ses  and sedges growing beneath the t r ee s  include Eragrost is  riparia, 
Cyperus ohtusiflorus, Kyllinga nemoralis, and Fimbr*s ferruginea. 
- .- .- 
Floristically the area  of Mixed Scruh on West Island is similar  to that on 
South Island, though probably with more  introductions f rom the settlement. 
Plumbago aphylla and the vine Ahrus precatorius, withits distinctive black and 
red seeds, were collected here in 1966, and leafless Euphorhia abbottii t r ee s  
were common. 
Acrostichum w, the only recorded fern, is widespread in the deeper 
clefts and sinkholes on South Island (Plate  23), both in the Mixed Scrub and in 
Pemphis thicket. 
It is likely that when the Mixed Scrub is better known i t  will be considerably 
subdivided, and differentiated in te rms of substrate  and location. 
2. Pemphis Thicket 
Pemphis Thicket is named af te r  i t s  dominant, Pemphis acidula, a species 
widespread on uplifted reefs  in the Indo-Pacific, but here extraordinarily lux- 
uriant (though ahsent i n  the Seychelles). The thicket has a maximum height of 
about 15 feet,  and though the trunks and branches of the Pemphis a r e  slender 
they a r e  extremely tough and grow in such profusion that penetration is diffi- 
cult. Because of i ts  association with the soil-less champignon, Pemphis 
Thicket occurs to seaward of the Mixed Scrub on South Island, and to a l e s se r  
extent along the lagoon shore. It covers  most of the exposed rock a r e a s  of the 
other main islands, except for  an a rea  of Mixed Scrub a t  the south end of West 
Island, and clumps of Pemphis a r e  found evenon minute reefrock is lets  in the 
lagoon. On the northern side of the atoll, Pemphis i s  normally the f i r s t  shrub 
met with at the cliff-top (Plate 2), and largely replaces the Scaevola-Tourne- 
fort ia  zone normally found in sandier habitats. Inland its dominance is reduced, 
and Pemphis is found with many of the Mixed Scrub species, forming a thicket 
that is much denser than the Mixed Scrub itself, and in places a woodland in 
which Pemphis itself is rare .  Mystroxylon aethiopicum and- sp. a r e  
common in such a reas  on South Island, and Dracaena reflexa was collected in 
dense mixed Pemphis thicket on West Island near Main Channel. In these 
transitional areas,  Pemphis is most dense round themargins of the la rger  
sinkholes, where it may be almost impenetrable, except with extreme labour. 
Smaller  flowering plants in potholes include the thorny Capparis --- galatea, with 
a conspicuous white flower, and wisps of Oldenlandia sp. Most of the rock sur- 
face beneath the shrubs is bare,  with spa r se  and scattered clumps of Mariscus 
ligularis and Eragrost is  B. 
--
The flatness of the ground combines with the uniform height (10-15 feet)  
of the vegetation to make travelling except with a compass very difficult; and 
Wharton (1883, 77) gives a graphic account of the difficulty of traversing 
I'emphis-covered champignon when he s ta tes  that "a walk in Aldabra i s  the 
most  aggravating and slowest piece of locomotion I have ever engaged in: and 
nothing short  of the patience, perseverance, and general disregard of time of 
the tortoise tribe can make i t  an agreeable residence. Some of my Negro sa i lors  
were sent into the bush to hunt for  tortoises, and after three days' search  
brought back one . . .; but they returned nearly a s  guiltless of artificial clothing 
a s  their captive." 
3. Mangrove Communities 
The mangrove communities have been discussed by F r y e r  and Vesey- 
FitzGerald. Both agree on the zonation of the genera: Bruguiera and Ceriops 
a t  the head of creeks; Rhizophora (&. mucronata) on deeper mud in the creeks  
themselves; Avicennia (A. marina) on open lagoon flats subject to tidal flood- 
ing; and Lumnitzera in isolated inland depressions. It has been argued (Wharton 
1883; F r y e r  1911, 403, 409) that the lagoon mangroves a r e  instrumental in 
eroding the lagoon margins, both by the mechanical effects of root growth in 
crevices, and by the chemical activity of mangrove mud. It can, however, be 
seen that the undercut lagoon margins and creek systems a r e  morphologically 
s imi lar  whether mangroves a r e  present o r  absent. Wherever mangroves were 
seen growing in intimate association with eroding cliff forms,  there was no 
evidence of mechanical activity; rather  the t r ee s  appeared to be growing in 
pre-existing holes. Fine carbonate sediment is certainly beingformed, however, 
and the processes need examination. The main mangrove area  surrounds the 
Bras  Takamaka, at the southeast end of thelagoon, where i t  totals more  than 
3 sq. miles. Large a reas  also exist on West Island (0.6 sq. miles), and a t  the 
west end of South Island, opposite Iles Moustique (1 sq. mile). Many of the smal l  
lagoon islands have a reas  of mangrove. The mangroves seen in Bras  Takamaka 
a r e  low and open. Taller t rees ,  up to 40 feet high, were seen on the lagoon side 
of Middle Island, where the mangroves perch precariously on the edges of lime- 
stone islands intersected by deep tidal channels. Tall mature mangroves were 
described on West Island by Dupont (1907), but there was no opportunity to s e e  
these in 1966. Half a century of exploitation for  timber and bark must  have 
severely modified the mangroves of West and nearby South Island, but no in- 
vestigation could be made of this  in 1966. Fur ther  damage is caused f rom time 
to time by cyclones, and defoliation is described by F r y e r  (1908-9). The man- 
groves play an important part  in the ecology of sea  and shore birds at Aldabra. 
4. Psammophilous Communities 
Frye r ' s  Shore Zone Vegetation, in which most of the plants a r e  common 
pantropical o r  Indo-Pacific s trand species, may be further subdivided in t e r m s  
of habitat. Vesey-FitzGerald (1942) distinguishes a spray-zone community, dune 
scrub, and a herb-mat communiry. The spray-zone community itself var ies  
with aspect. On the windward side of the atoll, from Takamaka to Point Hodoul, 
a narrow belt of blown sand a t  the cliff top is succeeded inland by a zone sev- 
e r a l  hundred yards wide of bare rugged champignon. At the seaward edge of the 
Mixed Scrub community, most of the la rger  shrubs and t rees  a r e  gnarled and 
dead, leaning away from the wind (Plate  20), and even Acrostichum, the leather 
fern, nestling in crevices, is shrivelled and brown. The living vegetation in this 
maximum exposure a rea  consists of dwarf flowering plants (Sida parviflora, 
--- 
Portulaca -- quadrifida, Evolvulus alsinoides, Hypoestes sp., Lagrezia madagas- 
cariensis ,  Oldenlandia -sieberi)  and sedges and g ra s ses  (Eragrost is  sp., Dacry- 
loctenium pilosum) sheltered from the wind i n  potholes and crev- izs ,  with thorn 
bushes such as Solanum aldahrense and Capparis galatea in the la rger  holes. 
Many of the common strand species, such a s  ~ourne fo r t i a ,  Scaevola, S- 
and Ipomoea a r e  absent from this habitat. 
In more  protected conditions, f rom Point Hodoul towards Anse Cedres, the 
Mixed Scrub and Pemphis communities approach within 30 yards of the cliff- 
-- 
top, and fo rm a hedge of Pandanus with occasional clumps of Scaevola sericea 
(Plate I) .  The zone between the Pandanus and the cliff edge, intermittently 
carpeted with sand, is colonised by a spa r se  community of coarse  tussock 
g ra s s  (Sclerodactylon microstachyum) with scattered low Scaevola andocca- 
sional Tournefortia.-~rom Anse C&dres westwards, the vegetation approaches 
within a few feet of the cliff edge and is dominated hv Pemphis. with occasional 
- - .  
Guettarda speciosa, Scaevola ser icea  and Tournefortia argenrea; a distinct 
spray-zone community can hardly be said to exist. 
No observations have been made on the south and west coasts of South 
Island. Most of the coast is presumably covered with dune scrub, with tall  
Sclerodactylon macrostachyum, low carpe ts  of a Paspalum-like grass,  and 
Scaevola and dwarf -- Guettarda, according to Vesey-FitzGerald (1942). A modi- 
fied dune scrub  is also found a t  the south end of West Island (Plate 9), where i t  
is interesting that some of the dwarf flowering plants, such a s  Sida parviflora, 
a r e  the same a s  those inhabiting potholes in the most  exposed spray zone of the 
windward coast. Tall shrubs on these dunes include &I& tetracantha and 
Acalypha claoxyloides, together with the g ra s ses  Dactyloctenium pilosum, 
-- -- 
D. aegyptium, and Eragrost is  riparia, the attractive b l u e - f l o w e r e r m  
- -- 
strigosa, and Scaevola. Low f r e sh  sand spi ts  belowthe dunes a r e  being colonised 
by the sedge Cyperus mari t imus and seedlings of Scaevola and Tournefortia 
(Plate 12). The low dunes between Takamaka and Point Hodoul a r e  occupied only 
by a turf formed by a Paspalum-like g ra s s ,  and bunch-grasses (Plates  6, 7 
and 8). 
Vesey-FitzGerald adds a third community, the herb-mat community, found 
in the western Indian Ocean islands particularly beneath dense bird colonies, 
hut this does not seem to have an Aldabra counterpart. 
5. Man-induced Vegetation 
To the vegetation types distinguished by F rye r  and Vesey-FitzGerald is 
added the category of man-induced vegetation. In addition to the 173 species 
listed in his flora, Hemsley (1919) r e f e r s  to a number of introduced economic 
species reported from Aldabra, including 
Amaranthus 
Amaranthus gangeticus 
Brassica nigra 
--- 
Carica papaya 
--
Gossypium barhadense 
Ocimum canum 
-- -
Ricinus communis 
Lochnera rosea 
C z o g  nucifera. 
Further  species were added to this l i s t  in 1966. 
Man-induced vegetation is of three main types: coconut plantation, Casuarina 
thicket and woodland, and village vegetation. Coconuts a r e  only found in small  
clumps at the settlement on West Island (Plates 38 and 39); intermingled with 
other species to form a coconut thicket onIle Michel; and reportedly also a t  
some of the pocket beaches a t  the westend of South Island (e.g. Anse Mais). 
Clumps of tall  Casuarina a r e  found at Anse Csdres (Plate 37), on both s ides  of 
East  Channel, at Ile Michel, and on both sides of Main Channel, a s  well a s  a t  the 
settlement on West Island (Plate  40). They vary from open woodland with no 
undergrowth to dense thickets of broken trunks andsaplings, though much of this 
damage observed i n  1966 had resulted from a recent cyclone. Needles carpet  
the ground, obscuring the i rregulari t ies  of the champignon and in places making 
walking dangerous, and apar t  f rom r a r e  Scaevola and Tournefortia seedlings 
there is no ground vegetation. At the landward margin there is some invasion by 
tall  spindly Scaevola and other plants, and the red flowers of the aloe-like 
Lomatophyllum borbonicum a r e  in places conspicuous. 
The introduction of coconuts and the spread of Casuarina date f rom the end 
of the nineteenth century. H.M.S. Fawn planted fifty coconuts a t  Ile Michel in 
1878, together with Casuarina (Findlay 1882, 550). Active planting of coconuts 
by lessees  began about 1880, and fo r  some time was made a condition of the 
lease. Dupont in 1906 found about 1000 coconuts a t  the West Island settlement 
up to 25 years  old, and the smal l  pocket beaches at the west end of South Island 
were also planted at this time (Dupont 1907, 21). It is likely that the main 
Casuarina groves, however, already existed a t  the time of the Fawn survey. It 
is said that James  Spurs, when lessee,  went s o  f a r  a s  to dynamite holes in the 
champignon in which to plant nuts, in h is  efforts to establish thriving coconut 
plantations (Anon. 1920). 
Village vegetation includes cultivated plants, such a s  cotton and sisal ,  and 
cultivated trees,  together with common pantropic weeds and cultivated decora- 
tive plants. Agave and Gossypium grow in the settlement itself, with thickets of 
-
Caesalpinia bonduc and tal ler  t r ee s  of Moringa pterygosperma. Fruitbats were 
seen in 1966 apparently feeding on the flower buds of - Agave during the day time. 
There a r e  also early reports  of the cultivation of maize and tobacco. The com- 
mon weed Stachytarpheta indica is found only a t  the West Island settlement, and 
near the abandoned fishing but on the west side of East Channel. The most com- 
mon decorative flowering plant, planted round most of the houses in the settle- 
& ment, is Catharanthus rosea, in both white and pink varieties. Clearly human 
settlements a r e  acting a s  foci f o r  the introduction of alien species, though these 
have not yet made much progress  against thenative vegetation and a r e  s t i l l  
sharply circumscribed. 
The role of man and animals in controllingnative vegetation needs study. 
Man has harvested mangrove fo r  t imber and bark since the 1880s (Dupont 1907, 
23-24), but on a small scale. Tortoises and goats crop the lower vegetation, 
including grasses,  sedges, and the lower leaves of t rees  and shrubs, particu- 
lar ly in the more open Mixed Scrub. Birds must have a considerable direct 
effect on leaves and branches, and an indirect effect on soils and the phosphorus 
cycle, particularly in the la rge  Middle Island breeding colonies, and this too 
needs further study. 
4. TERRESTRIAL FAUNA 
In common with most island faunas, that of Aldabra is notably disharmonic, 
with many groups unrepresented, and with a degree of probable endemism in 
those which are; and i t  i s  notable fo r  the survival there of forms unsuited to 
competition with introduced species, in which c l a s s  the land tortoise i s  the 
outstanding example. It is difficult to discuss the biogeography of the land 
fauna a t  the present time: in many groups the taxonomy itself has been in- 
adequately worked out; many groups a t  Aldabra have been collected only 
casually o r  not a t  all; and fo r  those which a r e  better known, particularly the 
insects and the land birds, so litt le work has been done in neighbouring a reas  
that the biogeographic relationships and degree of endemism a r e  uncertain. 
1. Mammals 
Mammals a r e  represented in the native land fauna only by fruit-eating and 
insectivorous bats, which a r e  also found in both the Seychelles and the Mas- 
carene Islands. The frui t  bat was collected by Abbott in 1892, and was described 
a s  an endemic species, Pteropus -- aldabrensis, by True  (1893). This beautiful 
animal was seen during the day in 1966 on the branches of large t r ee s  a t  
Takamaka Pool, though F r y e r  (1911, 416) s tates  that "it never fo rms  la rge  
gatherings on a t ree  during the daytime." The insectivorous bats a r e  more 
- 
widely distributed. F rye r  names them a s  Taphozous mauritianus and Triaenops 
-- 
furcula, and h4iller (1902) names one as Nyctinomus pusillus. The insectivorous 
- -- 
bats a r e  seen a t  dusk at the West Island settlement, and in the Casuarina groves 
-- 
a t  East  Channel, where a specimen takenin 1966 has been identified as Tada- 
r ida pumila (= Nyctinomus pusillus). 
-- -- 
2. Birds 
The land birds, of which there a r e  sixteen known resident species, a r e  most 
numerous in the Mixed Scrub on the platin, and in Casuarina and coconut groves. 
Benson (1967) considers that only one, the Drongo Dicrurus aldabranus, is a 
full species endemic to Aldabra, but at the same time only two of the native 
Aldabra land birds cannot be distinguished from other members of the same 
species in nearby a r e a s  (the Grey Heron Ardea cinerea cinerea and the Barn 
Owl Tyto alba affinis). Endemic subspecies a r e  thesacred Ibis Threskiornis 
--- -- 
aethiopica abbotti, the ra i l  Dryolimnas - cuvieri aldabranus, the nightjar 
Caprimulgus madagascariensis aldabrensis, and the fody Foudia eminentissima 
-- 
aldabrana, the last of which commonly occurs a t  tbe West Island settlement and 
in Casuarina woodland elsewhere. Good subspecies found on Aldabra and also 
on nearby reef islands a r e  the little Green Heron Butorides -- str iatus crawfordi, -- 
the Madagascar Turtledove Streptopelia picturata copp-i, - and the Soui- 
manga Sunbird Nectarinia sovimanga aldabrensis. Aldabra also has l e s s  dis- 
tinct forms of the kestrel  Falco newtoni aldabranus, the Comoro Blue Pigeon 
Alectroenas sganzini minor, the Madagascar Coucal Centropus e u  insularis,  
the Madagascar Bulbul Hypsipetes madagascariensis rostratus,  and the 
Madagascar White-eye Zosterops ---maderaspatana aldabrensis. Benson finds the 
land avifauna to be mainly of Madagascan origin, and suggests colonisation 
either via the Comoros o r  via Gloriosa and the islands to the eas t  of Aldabra. 
Fo r  detailed consideration of the native land birds, and also of recent  a r r iva ls  
such a s  the Pied Crow Corvus albus, s e e  the accompanying papers by Benson 
(1967) and Gaymer (1967): three species only a r e  considered further  here, on 
account of their susceptibility to human interference. 
The White-throated Rail Dryolimnas cuvieri aldabranus (Gunther 1879) is 
almost flightless. Rails, many of them flightless, a r e  found on islands through- 
out the world, though many of the insular populations have recently become ex- 
tinct following the introduction of predators  and increased human activity. Thus 
the ra i l s  of Laysan and Wake Island in the Pacific have both recently become 
extinct. F rye r  (1911, 418) reported that the Aldabra rai l  '5s  generally distributed 
over the atoll, though i t  is sca rce  on Picard (West Island), and has generally 
been exterminated in the neighbourhood of Takamaka by the cats". Abbott (1893, 
762) feared that the ra i l  would soon be exterminated, "as their a rch  enemy, the 
cat, has already exterminated them from Grande T e r r e  (South Island), and must 
sooner o r  later  reach the other small  islands of the group, where the r a i l s  a s  
yet abound in great numbers". Voeltzkow (1897, 63) had found them plentiful 
and extremely tame. They have been recorded from Ile Espri t  by F r y e r  (1911, 
418) and from Ile Michel (Anon. 1920, Ch.8, 9; Vesey-FitzGerald 1940, 487). 
Rails now exist on Middle Island, where they were seen in 1966, and on 
Polymnie (Bourne 19661, but they have disappeared from West Island. Abbott 
(in Ridgway 1895, 528-529) gives an account of their behaviour. Related birds 
formerly existed on Assumption, Cosmoledo and Astove, buthave al l  become 
extinct in this century, and the flightless ra i l  of Aldabra is now the las t  of the 
flightless birds of the Indian Ocean islands, a s e r i e s  which once included the 
dodo and the solitaire (Lorenz 1908, Hutchinson 1953). 
The Sacred Ibis Threskiornis aethiopica w, is conspicuous on South 
Island, particularly round the major  freshwater pools, each of which has one 
o r  two birds (Plates 28 and 32, and illustrations in Nicoll 1908). At Takamaka 
i t  i s  s t i l l  extremely inquisitive and has to be kept away from baggage, as 
described by Nicoll (1908, 121), but elsewhere i t  i s  less approachable. It i s  
r a r e  a t  the west end of the atoll, and was absent from West Island near  the 
settlement fifty years  ago (Nicoll 1908, 119). F rye r  (1911, 417) reported i t  on 
Ile Michel, and also described the destruction of eggs by the birds in a nesting 
colony on South Island (1911, 417-418). Gaymer found the sacred Ibis nesting 
at Takamaka (Plate 33). Because of itsinquisitiveness i t  would undoubtedly 
suffer if the human population of Aldahra increased. 
Another species in considerable danger is the flamingo, Phoenicopterus 
ruber roseus, which is not yet definitely known to breed, and which Benson 
--
(1967) does not consider to be distinct. Abhott in 1892 found a population of 
500-1000 birds, in flocks of 20-60 individuals, on the south and eas t  shores  of 
the lagoon (Ridgway 1895, 529). Dupont (1907, 21, 23) reported numerous flocks 
of several  hundred birds along the south side of the atoll, and he and F r y e r  
(1911, 419) describe their flight and cries .  More recently, Travis  (1959, 202) 
noted "several small flocks" on the north side of the atoll, but the Bristol 
Seychelles Expedition suggested that there may be only 50 left, and that the 
survivors breed in the Bras  Takamaka (Plate 36). It was not seen in 1966. 
F r y e r  collected the bird louse Esthiopterum subsignatum f rom this species in 
1908-9 (Scott 1914). 
Sea and other shore birds a r e  numerous (Vesey-FitzGerald 1941; Benson 
1967), and include both breeding and migrant species. Frigate birds (Fregata 
minor aldabrensis and F. a r i e l  i redalei)  and Red-footed Boobies (Sula sula 
rubripes) nest in great  numbers in the mangroves of Middle Island, where the 
fo rmer  a r e  concentrated towards Eas t  Channel and the lat ter  near  Johnny 
Channel, though the nests of both species a r e  intermingled. F rye r  (1911, 419) 
reported a nesting colony of fr igates on West Island which has now disappeared. 
A s  is usual with this species the fr igatesparasi t ise  the boobies, spending the 
day soaring on a i r  cur rents  to heights of a few thousand feet over the windward 
end of the atoll, awaiting the return of the boobies with food. Though no ade- 
quate observations could be made of these vastcolonies in 1966, i t  appeared that 
the number of frigates greatly exceed that of boobies. Several of the la rge  
freshwater  pools on South Island a r e  frequented by frigates, which dive con- 
tinuously to drink, scooping up water f rom the surface in their beaks while still  
on the wing (Plate 29). Similar diving behaviour of frigates (in this ca se  F. 
minor palmerstoni) has been reported from a freshwater pool on Canton atoll in 
the Phoenix Islands (Degener and Gillaspy 1955, 6). It is thought that the Aldabra 
fr igate colonies s e rve  as the major  breeding ground for  the fr igates of the 
western Indian Ocean, and that a considerable non-breeding population may be 
scattered over this a r ea  (W. R. P. Bourne, personal communication). If an air- 
field were to he built at Aldabra, thefr igates would clearly represent  a major 
aviation hazard, s imi lar  to that of the albatrosses a t  Midway Atoll in the Pacific 
(Fisher  1966), and any control measures  would have to take account of the fact 
that birds may continue to return to Aldabra to breed fo r  several  years. 
Red and White-tailed Tropicbirds (Phaethon ruhricauda rubricauda, r. 
lepturus lepturus) were seen nesting on the ground on lagoon i s le t s  near  East  
Channel in 1966. Other very common s e a  birds include the Noddy - Anous -- stoli- 
dus -- pileatus, breeding on lagoon i s le t s  (Ridgway 1895, 527), and fairy te rns  
(Gygis alba monte). 
- 
Shore and wading birds a r e  especially numerous, particularly in the lagoon 
a t  low water. Dimorphic egre ts  Egretta garzetta dimorpha, in both white and 
dark phases, a r e  perhaps most striking; together with the Crab  Plover Dromas 
ardeola, the Turnstone Arenaria -- interpres interpres, the Sanderling Crocethia 
alba, the Grey Heron Ardea cinerea cinerea, and the Little Green Heron 
Butorides s tr iatus crawfordi. Fo r  other records, s e e  Benson (1967). The feed- 
ing hehaviour of the shore  birds on the lagoon flats and their dependence on the 
unstudied invertebrate fauna would repay detailed investigation. 
3. Land Reptiles 
The land tortoises of Aldabra form, with those of the Galapagos Islands, the 
only surviving native populations of this giant form. Most of the study of these 
reptiles has been made on museum specimens, often of doubtful origin, and 
until recently no work had been carr ied out on the Aldabra species in the field. 
On the basis of museum identifications, two speciesin the Linnean genus 
Testudo -have been segregated for  the Aldabra tortoises: Testudo daudinii Dum. 
-- 
and Bibr., on South Island, and T. elephantina Dum. and Bibr., on Middle Island 
(Rothschild 1915; s e e  also Siehenrock 1904). Giinther (1877) distinguished 4 
species in the Aldabra group (i.e. Madagascar, Seychelles, and small  islands in 
between) of giant land tortoises, 5 in theMascarene group, and 6 in the Gala- 
pagos Islands; Rothschild (1915) found 7 (plusapossible 2), 8 (plus a possible 2)' 
and 13 (plus a possible 2) in each group respectively. Williams in 1952 placed 
the Aldahra tortoises in one species, in thegenus Testudo, subgenus 
chelys, species Testudo gigantea Schweigger; with the Galapagos tortoises in 
-- --
the single species Testudo -- elephantopus (Williams 1952). In their revision of the 
Order Testudinata, however, Loveridge and Williams (1957, 225) place hoth the 
Aldabra and Galapagos tortoises in the genus Geochelone Fitzinger (Family 
Testudinidae, Subfamily Testudininae). They erec t  a new subgenus Aldabra* 
Lov. and Will. f o r  the Aldabra tortoise, with the single species gigantea 
Schweigger (Plate 26). The specific name elephantopus is retained fo r  the 
Galapagos tortoise, genus Geochelone, subgenus _Chelonoid& (Williams 1952). 
Comparative field studies of South and Middle Island tortoises by the Bristol 
Seychelles Expedition a t  Aldabra failed to establish any differences between the 
supposed species (R. Gaymer, personal communication). Geochelone (& 
brachelys) gigantea of Aldabra has close relatives i n  the Pleistocene and 
Recent of Madagascar and rhe Indian Ocean islands, and in the Eocene of the 
Fayum depression, Egypt (Williams 1952; s e e  also Wermuth and Mertens 
1961). 
Figure 5, based on data in Rothschild (19151, maps the distribution of the 
Indian Ocean giant tor toises in the early eighteenth century, when, according to 
Rothschild, they extended f rom Madagascar to the Seychelles, the Mascarenes, 
and even to the Chagos Archipelago. In the early eighteenth century, tortoises 
were abundant on Mauritius, R&union, and Rodriguez; but during the period 
1750-1800 they became extremely rare ,  and had disappared before 1840. In the 
eighteenth century they were  abundant in the Seychelles and some of the smaller  
islands of the south-west Indian Ocean; but they had disappared on the main 
islands and on most of the l e s s e r  ones by 1840, surviving only a s  semi- 
domestic animals in a few places. We havefound confirmatory records  in the 
l i terature of the fo rmer  existence of giant tortoises on the small  islands of 
Assumption, Astove, and Cosmoledo, a s  well a s  Aldabra; but not f o r  Gloriosa, 
Farquhar, St P ier re ,  and Providence, which Rothschild also cites, though 
Figure 5.--Distribution of giant land tortoise in the eighteenth century in the Indian Ocean, 
after Rothscliild (1915) 
Coppinger in 1882 found seven giant tor toises imported from Aldabra roaming 
in the woodland on Providence (Coppinger 1883, 234). Nor can we find any rec- 
ord of wild populations in the Chagos Archipelago. These records  a r e  there- 
fo re  marked a s  doubtful in Figure 5. Thecase  of Providence is an example of 
the manner in which, a s  described by Rothschild, domestic herds were re- 
cruited f rom many different islands, and how transferof wild tortoise took 
place f rom one island to another, thus making any detailed study of original 
variation impossible. Some of the Seychelles domestic tortoises, of unknown 
provenance, were released, fo r  example, on the northand west islands of 
Aldabra (Rothschild 1915, 433). 
The massive decline in tortoise numbers in the Malagasy Region seeins to 
have resulted from many factors. Direct predation by man for  food seems  to 
have been considerable. Sauzier (1893) records exports f rom the Seychelles 
and Mauritius of more  than 3000 tortoises in 1826, fo r  example, and in 1847 
two ships took 1200 tortoises f rom Aldabra alone (Rothschild 1915, 424; 
Voeltzkow 1897, 59; Parsons 1962 wrongly states  that the animals were 
turtles). This trade was probably episodic; but with such a long-lived animal 
on such small islands i t  could only havedrast ic  long-term population con- 
sequences. Pens built of coral  blocks in the nineteenth century, fo r  confining 
tortoises prior  to export, can still  be seen in severa l  places on Aldabra, a s  a t  
Anse Ckdres and Cinq Cases,  and a r e  stilloccasionally used fo r  this purpose. 
Second, the disturbance of the environment, particularly by the clearing of 
vegetation and the spread of cultivation, a s  in the Galapagos, forced the tor- 
toises into more marginal environments, especially in thehigh islands. By the 
time that massive guano digging and habitat modification began in the smaller  
reef islands of the southwest Indian Ocean, the tortoises had generally disap- 
peared: except a t  Aldabra, where fortunately commercial guano was absent. 
Third, tortoise numhers were  directly affected by the introduction of competi- 
t o r s  and animal predators. In the Galapagos, for  example, fe ra l  pigs attack and 
kill young tortoises, and r a t s  and dogs also ha rm the young and may destroy 
eggs. The introduction of goats, cattle and donkeys in the 1920s led to direct 
competition for  food (Snow 1964), and recent studies have suggested that the 
Galapagos torroises wi l l  become extinct in this century (Hendrickson 1966, 
256). By the time that such introduced species spread to the smal ler  Indian 
Ocean islands, however, the tortoise populations had disappared, except at 
Aldabra, where the r a t s  and f e ra l  goats do not seem to he a threat  to tortoise 
survival. 
Little is known of tortoise ecology a t  Aldabra, though a s t a r t  has been made 
in field observation hy the Bristol Seychelles Expedition. Voeltzkow collected 
some specimens, and F r y e r  (1911, 420-421) gives brief notes, but otherwise 
scientific attention has concentrated on the more accessibleGalapagos tortoises. 
Recent studies have been made hy Honegger ( inpress)  in 1964 and by the 
Bristol Seychelles Expedition 1964-5 (Gaymer, in press).  At Aldabra, the tor- 
toises a r e  concentrated on the platin (Plate 27), and a r e  r a r e  on champignon, 
where because of the i r regular  te r ra in  and dense vegetation movement is dif- 
ficult. No reliable est imate is possible of total numbers, though inland from 
Anse ~ k d r e s ,  57 were seen in a t raverseof 1 hour in 1966, and 200 in l e s s  than 
2 hours in a t raverse  between the lagoon and Takamaka Pool. Prosper i  (1957, 
201) suggested a total of 80,000 in 1953, and the Bristol Seychelles Expedition, 
from sample counts in three  a reas  of South Island (at Anse Mais, with 360 tor- 
toise in 3 sq. miles; a t  Takamaka, with 176 tortoise in 4.5 acres;  and in another 
a r ea  of platin, with 8 tortoise in 19,200sq. yards), and extrapolation on the 
basis of a r eas  of platin and champignon shown on published maps, suggest 
totals of 30,000 tortoise on South Island, 3,3700n Middle Island, and perhaps 
several  hundred on West Island (Gaymer, personal communication). From our 
observations i n  1966, we would place the total a t  more  than 10,000, hut we 
would also s t r e s s  the variability in hahitat on South Island, and the need fo r  
caution in extrapolating sample counts, especially f rom lines of rapid traverse, 
which a r e  likely to be the most  open and hence most favourable locations. This 
order  of magnitude contrasts  strongly with the totalof 1,000 estimated by James  
Spurs (Griffith, in Fairfield and others  1893, 153), and the general f ea r  of im- 
minent extinction and declining number in the second half of the nineteenth 
century. Wharton's s a i lo r s  spent three days finding one tortoise in 1878 
(Wharton 1883, 77). F r y e r  (1910, 258) comments that "it would be possible to 
live for  years  on Aldabra and never see  a specimen." These repor ts  may either 
indicate a spectacular increase in numhers in the l a s t  one hundred years ,  o r  
may simply resul t  f rom the general rar i ty of tortoise in the a r e a s  of champignon 
and their concentration on platin at the remoter  eas tern  end. 
The greatest  numbers of tortoise a r e  found attached to the freshwater pools 
on the platin a t  the eas t  end of South Island, though in the wet season they may 
be more widely-ranging. A few pools were seen crowded with tortoise (one with 
more than 80) in 1966, the tortoises lying in the mud and shallow water during 
the early morning (Plates  24, 25 and 28). Towards 10 a.m. they move to the 
shade of adjacent Pandanus, o r  a t  Takamaka (Plate 22), and stay there 
until sundown. We have no information on their nocturnal behaviour. Many of 
the pools, when almost dry, a r e  green with organic matter,  and chis resul ts  in 
the formation of concentric drying marks  of green o r  blue round the pool mar- 
gins and on the hacks of the tortoises. It was noticeable that tor toises with a 
given drying-mark colour were not found f a r  from the corresponding pool. Many 
of the pools contained one o r  two dead tortoises. The animals a r e  said to breed 
during the wet season, f rom January to April (Anon. 1920, Ch. 12, 8). On the 
South Island platin, droppings a r e  found every few yards, and tortoises them- 
selves a r e  ra re ly  out of sight. According to F r y e r  (1911, 420), they a r e  also 
found on both West and Middle Islands, though on the lat ter  he found only two 
specimens. Abbott (1893, 761) and Dupont (1907, 20) record that i t  became ex- 
tinct on West Island in 1880, but was reintroduced a few years  later  by James  
Spurs, the lessee. In 1966 we found freshdroppings on Middle Island, but saw 
no tortoise. The tortoise clearly thrive in the platin habitat, feeding on sedges 
and g ra s ses  and the lower leaves of shrubs, even standing on their hind legs to 
reach these. The carrying capacity of the champignonis clearly much lower, and 
on the hare, seaward-coast champignon between Takamaka and Point Hodoul 
there a r e  great  numbers of bleached carapaces. Numbersof tortoises seem to 
wander into this barren area,  and can be found sheltering in holes, under r a r e  
hushes, and even under washed-up tree-trunks on the cliff top, in what is during 
the dry  season a completely waterless environment. 
The conservation of the tortoises is discussed in Section 6(3)(a). 
Aldabra has no snakes and no amphibians, and apart  from the tortoises the 
land reptiles a r e  represented hy only two geckos and a skink. The geckos a r e  
Hemidactylis mercatorius (the H. gardineri of Boulenger 1911) and Phelsuma 
- - 
ahhotti ahbotti (the P. madagasc r i ens i s  abhotti of Boulenger 1911 and Stejneger 
- - --- 
1893). Hemidactylis is also found on Astove, Assumption and Cosmoledo 
--
(Honegger 1966b); Stejneger (1893) recorded H. mabouia from Aldahra, but 
Boulenger (1911) considered this to be identical withhis. gardineri.  Phelsuma 
abbotti abhotti is also found on Assumption, and f o r m s  part  ofeseriesfspe-- 
c ies  and subspecies of this genus in the southwest'1ndian Ocean, with P. abbotti 
menaiensis and a possible undescribed subspecies on Cosmoledo and 
P. astr iata  astovei on Astove (Mertens 1962, Honegger 1966b; also Boettger 
1913). In 1966 we observed Phelsuma in symbiosis with the tortoises on South 
Island, running on the carapace and feeding on the Aedes mosquitoes which 
congregate round the soft neck and underparts of the tortoise; and a s imi lar  
observation has been made by Honegger (1966h, 31). The skink Ablepharus 
boutonii peronii (Boulenger 1911) is of a species also found on Astove, Cos- 
moledo and Assumption. 
38 
4. Insects 
By contrast the fauna is particularly r ich in insects,  especially by compari- 
son with other Indian Ocean islands. While the Seychelles have more than two 
thousand species of insects  recorded, none of the cora l  islands of the western 
Indian Ocean has more  than one hundred, with the exception of Aldabra, which 
has more than 360 (Scott 1933, Legrand 1965). While this partly ref lects  the in- 
tensity of collecting by Abhott, Voeltzkow, Dupont, and especially by Fryer ,  
himself an entomologist, i t  is also the resul t  of the la rger  s ize  and habitat 
diversity of Aldabra compared with the other coral  islands, and also of i t s  
proximity to Madagascar. 
The largest  group represented is the Order Lepidoptera. After the Percy 
Sladen Expeditions there were 66 species recorded, with 7 endemics. Legrand's 
(1965) recent monograph, including the resul ts  of his  own collecting together 
with that of the Italian Zoological Expedition of 1953, adds many new records 
of Microlepidoptera and increases the total to 127 species, 35 of which a r e  
endemic (about 28 per  cent), and of which 12 a r e  represented by endemic sub- 
species. The Order Coleoptera is represented by 93 species, of which 16 a r e  
thought to be endemic (about 25 per cent): three of these endemic species be- 
long to endemic genera (Keeta, -with two species, and Bikasha, with one: Maulik 
1931). Other well-represented orders  include the Diptera, Hymenopteraand 
Orthoptera. Scott (1933) gives biogeographical comments on each order ,  and 
Table 4 keys the entomological li terature of Aldabra. Apart f rom cosmopoli- 
tan species, the insect affinities a r e  dominantly Madagascan o r  East African, 
with few Oriental o r  Mascarene forms.  Most of the possible endemic species 
a r e  close to Madagascan forms, though s o  l i t t le i s  known of insect faunas in the 
Indian Ocean that Scott himself prefers  the te rm "potential endemic" fo r  spe- 
cies  s o  f a r  recorded nowhere else. The Aldabrainsect fauna thus contrasts  
strongly with that of the Seychelles, which isdominantly Oriental in character  
(Scott 1933). 
Apart f rom the species l i s t s  there i s  almost no information on the ecology 
and distribution of the insects  of Aldabra, and the differences between the faunas 
of the champignon, platin and mangrove habitats. Information is also required 
on the insects associated with the la rge  bird colonies. 
Part icular  interest  attaches to the mosquitoes of Aldabra because of the po- 
tential danger of malaria, which in fact occurred a t  Aldabra in 1908 and in 
1930. F r y e r  collected Aedes aegypti (A. fasciata) at West Island, and 
albocephalus (Reedomyia seychellensis) and Aedes f rye r i  (Culicelsa f ryer i )  at 
Takamaka (Theobald 1912), the latter also taken by Dupont. Mattinly and Brown 
(1955) also record  Culex -- sitiens Wied., collected by Dupont in 1907. Anopheles 
gambiae has been collected only once, in 1930 (Hermitte 1931), a t  the time of 
the malaria outbreak. This  mosquito was then breeding only in small  rainwater 
pools in West Island, and does not seem to have survived. In 1966 we took only 
A. e. 
- 
Two species of horseflies taken in 1966 have been identified as  Aegopha- 
gamyia remota and Neavella albipectus. 
--
Table 4. Key to the Literature on the Insects of Aldabra 
- 
THYSANURA and COLLEMBOLA Fletcher  1910a, 1910b 
Carpenter 1916 F r y e r  1912 
Hampson 1908 
ORTHOPTERA 
Bolivar 1912 
De Saussure 1897 
Linell 1893 
DERMAPTERA 
Burr  1910 
ISOPTERA 
Holmgren 1910 
Wasmann 1897 
EMBIOPTERA 
Enderlein 1910 
ANOPLURA 
Scott 1914 
ODONATA 
Calvert 1898 
Campion 1913 
Linell 1893 
~ e r b u l o t  1962 
Holland 1895 
Karsch 1900 
Legrand 1965 
Meyrick 1911 
Viette 1958 
COLEOPTERA 
Aurivillius 1922 
Bernhauer 1922 
Champion 191 4 
Fai rmaire  1896 
Gebien 1922 
Grouvelle 1913 
Kerremans  1914 
Kolbe 1902 
Linell 1897 
Maulik 1913 
~ 6 g i m b a r t  1900 
Schenkling 1922 
Scott 1912, 1913, 192223, 1926 
Sicard 1912 
HYMENOPTERA 
Cockerel1 1912 
Fore1 1897, 1912 
HEMIPTERA Fr i e se  1902 
Bergroth in Voeltzkow 1920b Meade-Waldo 1912 
Distant 1913, 1917 Turner  1911 
Green 1907 
Line11 1893 DIPTERA 
Mamet 1943 Eaton 1913 
Edwards 1912 
NEUROPTERA 
Needham 1913 
LEPIDOPTERA 
Aurivillius 1909 
Berio 1956, 1959, 1962 
Bourgogne 1963 
Hermit te  1913 
~ e r t h s z  1912 
Lamb 1914, 1922 
Linell 1893 
Mattinly and Brown 1955 
Scott 1914 
Stein 1910 
Theohald 1912 
5. Other groups 
Little can be added on the other te r res t r ia l  groups to the results of collect- 
ing by Abbott, Voeltzkow, Dupont and Thomasset, and Fryer .  The land crustacea 
have been reported by Rathbun (1894), Lenz (1905). and Borradaile (1910), who 
listed 17 species in 10 genera. The brachyuran decapod crustacea have recently 
been revised by Guinot (1964). using the collections made by Cherbonnier in 
1954. She l is ts  33 species in 21 genera, including one new to science (Xanthias 
cherbonnieri). The land crustacean fauna is remarkable chiefly for  the presence 
of the robber crab,  Birgus -- latro, which is also reported from the Chagos Archi- 
pelago but is absent from the Maldives: clearly on Aldabra i t  cannot feed on 
coconuts. Cardisoma carnifex is common round the freshwater pools of the 
platin. There is a single earthworm (Ehlers 1897); a common scorpion (Iso- -
metrus maculatus, Hirst  1913); and several  spiders  (Hirst 1911). one of which, 
Nephila madagascariensis, is particularly prominent in the Mixed Scrub of the 
South Island platin, forming a large and strong web. 
There is an inadequately known land molluscan fauna, which includes one 
endemic species, Rhachistia aldabrae (Von Martens, in Von Martens and 
Wiegmann 1898, 28, as Buliminus (Rhachis) aldabra), collected by a Mr  Wilson 
i n  1895. Other records  listed by Connolly (1925) a r e  G a a  (Molarella) gwen- 
w, Gastrocopta tripuncta, Succinea mascarenensis,  1Gdora f o r k a l i m -  L___ 
m-a punctum, -- A. parvula, and Truncatella valida. The microfauna is particu- 
larlv ~ o o r l v  studied. In 1966. f o r  example, we found a rich freshwater  
. - - .  
microfauna in the drying platin pools, including crustaceans (fairy shrimps 
SJreptocc;pha&us, sp., C O ~ C ~ O S ~ I ' ~ C ~ ~ S  . - . UulimnaJid . - . . .. s):., and  c ~ s t r ~ ~ c ~ ~ d s \ I t . t ~ - r , c y p r i s  . .. . . .- . -. 
i p . )  3nd m ~ l l u s c s ,  i~.cluJing a spec i i s  of 1luli1.u;. \Vc also o b r a i r ~ d  3 semi- 
freshwater fish of the widespread gobiid genus Tamanka from the freshwater 
well a t  Cinq Cases: this was the f i r s t  recordof a freshwater  f i sh  f rom the atoll. 
5. MARINE BIOTA 
1. Turtles 
The marine biota of the Aldabra groupof islands is best known f o r  its 
turtles: Aldabra, Cosmoledo and Assumption support "the greatest  concentra- 
tion of breeding turt les  in the Indian Ocean in modern times, and perhaps i n  
antiquity" (Parsons 1962, 47). It is, therefore, extraordinary that no field study 
of these turtles has ever  been carr ied out, and that the available information is 
largely based on local r epo r t s  and hearsay se t  down by infrequent visitors. 
The green turtle, Chelonia mydas L. (Loveridge and Williams 1957, 472-484; 
Parsons 1962), is by f a r  the most important on Aldabra, though i t  is now r a r e  
a s  a breeding species on Cosmoledo and may have vanished from Assumption. 
The hawksbill, Eretmochelys imbricata L., taken for  i t s  shell, i s  found in much 
smaller  numbers, and a t  Aldabra has a distinctively lighter shell than else- 
where in the Seychelles, as  a result,  according to Fryer ,  of the muddiness of the 
lagoon. The loggerhead, Caret ta  caretta L., is also thought to occur, but does 
not seem to have been positively identified. Hornell (1927) draws attention to the 
fact that not only is the distribution of the hawksbill and the green turtle re- 
versed (the fo rmer  being abundant in the Seychelles and r a r e  at Aldabra, and 
vice versa) ,  but also that their breeding seasons alternate. The hawksbill 
breeds from September to November, and comes up the beaches during the day; 
whereas the green, a nocturnal egg layer, lays from February through to 
September. Hornell believes that the green turtle appear from their feeding 
grounds, presumably in the Mozambique Channel, f rom December onwards, and 
+. begin to lay in February, perhaps in twogroups of different origins (the main 
group in February-March, and a subsidiary group in May-September). However, 
there is no month in which turtles a r eno t  coming up the beaches to lay (Hornell 
1927, 31). The numbers of turt les  were declining rapidly by the end of the las t  
century (Spurs 1892), and Hornell forecast  ultimate extinctionif exploiration 
continued under the lessee  system without any attempt a t  conservation. Con- 
siderable losses  of newly hatched green turt les  were also said to have been 
caused by predation by herons and fr igatebirds (I-Iornell 1927). Voeltzkow (in 
Boettger 1913) suggested that 3000 a year  were los t  in this way. Later surveys 
in 1948-49 (Wheeler 1953b) and more recently (Veevers-Carter 1962; Newman 
1965; Gaymer 1 9 6 6 ~ )  have shown that the decline in numbers has continued, 
though this is not precisely documented. Conservation measures  and their 
resul ts  a r e  considered in greater  detail in Section 6(3)(b). Field studies to 
establish the s tatus of the marine turt les  a t  Aldabra and nearby islands a r e  
urgently required. 
2. Other groups 
Apart f rom the turtles, little is known of the marine biota, which does not 
appear to be rich. Voeltzkow made a smallcollection of marine fishes (Jatzow 
and Lenz 1899), echinoderms (Ludwig 1899), cora ls  (Doederlein 1901), and 
marine tnollusca (Thiele 1902, 244-246), but only the la t te r  were a t  al l  thor- 
oughly collected, and the fauna was typically Indo-Pacific. Travis  (1959, 159- 
166, 182-188) draws attention to the abundance ofT- on the forereef slopes 
on the eas t  and south sides of the atoll, and this species is also found on the 
reef-flat boulder zone. The coral  fauna appears  curiously poor, by comparison 
with the period when the reef  limestones wereformed; s o  much s o  that Gardiner 
(1936, 426) drew a distinction between the decadent and eroding reefs  of the 
Mascarene region, including Aldabra, and the flourishing, growing reefs  of the 
Maldives and the Chagos. This conclusion is supported by Stoddart's own ob- 
servations a t  Aldabra and in the Maldives. Apart from the forereef slopes, reef 
corals  a r e  only actively growing on the margins of the two main channels into 
the lagoon, and these a r e  mostly massive slow-growing species: a few a r e  
listed by Matthai (1914, 1928). Fryer ' s  small collection of marine algae was 
named by Madame Weber-van Bosse (1914). The commercial fishery potential 
of Aldabra was investigated by the Mauritius-Seychelles FisheriesSurvey in 
1948-49, and found to be disappointing (Wheeler andommanney 1953; Wheeler 
1953a). The invertebrate fauna of the lagoon, which is almost entirely un- 
studied, must  be considerable to support the large numbers of shore birds. 
42 
6. SETTLEMENT, EXPLOITATION, AND CONSERVATION 
1. Human Settlement 
The early history of human settlement a t  Aldahrais  obscure. Voeltzkow 
(1897) summarises  early knowledge, mainly f rom the char t s  in A. Grandidier's 
Atlas d e r  Karten von Madagascar, f rom the sixteenth century onwards. Aldabra 
did not become well known until the middle of the eighteenth century, when 
Lacaze Picault and Jean Grossen called there in the C B s  and the Elizabeth 
in 1742 (Findlay 1882; Keller 1901). According to Horshurgh (1852, 174-176), 
Aldabra was visited in August 1756 by a "Mr Morphey" (Nicolaus de Morphy), in 
November 1766 by the ship A 4  andinDecember 1815 by the Lord Castlereagh. 
Commander R. Moreshy passed close by in August 1822, but did not land. Alda- 
bra was visited in 1841 by Captain Jehennein the ship Prkvoyante (Voeltzkow 
1897, 41). The ship Euphrates, out of London for  Karachi, anchored in the la- 
goon in 1862. At a much l a t e r  date the German c ru i se r  Konigsberg hid in Main 
Channel f o r  two months in 1915, before beingdestroyed by English warships on 
the African coast. 
The atoll was apparently uninhabited in 1878, when H.M.S. F s ,  Com- 
niander Wharton, carr ied out the f i r s t  hydrographic survey. In 1879, however, 
an attempt was made to set t le  by apar ty  of 27 adults and 13 children, al l  Nor- 
wegians from Bergen, who arr ived via Nossi-B& to found a fishing station on 
communistic principles (Anonymous 1879; Reclus 1889, 155). The fa te  of this 
scheme is unknown. Shortly afterwards it was decided by the Government of 
Mauritius to exploit the atoll by leasing i t  commercially for  a small  annual 
rent. The f i r s t  lease was allotted to Jules Cauvin of Mah6 in 1888. Cauvin 
established a settlement a t  Ile Magnan in West Channels, where he planted 
coconuts while exploiting timber. In 1890 the leasepassed  to James  Spurs, a t  
a rent  of Rs. 500 pe r  annum, and he held i t  f o r  ten years ,  moving the settle- 
ment to Ile Picard o r  West Island, i t s  present site. Spurs had worked for  many 
years  a s  a manager a t  Diego Garcia in the Chagos Archipelago (Scott 1961, 165- 
169). The Administrator of the Seychelles considered that "the Government a r e  
fortunate in having secured Mr Spurs for  a tenant; for  i t  will be gathered from 
his report  . . . that he is an observant man and a lover of Nature, nor do I think 
he is likely, to use an old and homely phrase, to kill  the goose that lays the 
golden eggs by exhibiting that rapaciousness which has characterised the actions 
of others  who have been there before him" (Griffiths, in Spurs 1892, 45). Never- 
theless, Spurs proposed to take up to 12,000green turtle a year from Aldabra, 
for  what was then a "trifling" rent. He did, however, attempt to repopulate West 
Island with tortoises, warned of the disappearance of the hawkshill and of the 
consequences of taking many more female than male green turtles,and even 
brought Chinese to Aldahra from Mah6 to make trepang. By the time of Voeltz- 
kow's visit  in 1895, there was  a settlement a t  West Island of 20 Seychellois 
labourers  in ten houses, growing maize and vegetables, and taking turt les  and 
tortoises (1Celler 1901; and also F r y e r  1910 for an illustration). The ear l ie r  
settlement s i te  at Ile Magnan, and the s i te  a t  Ile Michel, recommended after  
H.M.S. Fawn's survey a s  "the only suitable place fo r  building a house" (Findlay 
1882, 550). had both been abandoned. 
The lease  passed in 1900 to Messrs  Baty, Bergne and Co., a t  a rent  of Rs. 
3000 pe r  annum, and the company concentrated on fishing rather  than on tim- 
ber; and also planted many coconuts (cf. Baty 1896). In 1904 M. D'Emmerez de 
Charmoy became the lessee, with James  Spurs a s  his  manager; and his admin- 
istration became notorious for  i t s  wasteful and inefficient exploitation of the 
turtle industry (Hornell 1927). D'Emmerez was st i l l  l essee  a t  the time of 
Fryer ' s  visit  in 1908-9; and the atoll was leased in this way until 1945, when 
commercial exploitation lapsed temporarily. The lease  was renewed ten years  
later,  when in 1955 M. Harry Savy of Mah6 obtained a 30 year  lease, with an 
option on a further  20 years. His company employs up to 100 labourers  to work 
the atoll, under contract from the Seychelles for  periods of up to three years. 
They live in well-built wood and cement houses on West Island, and a r e  sup- 
plied by schooner from ~ a h 6 .  Rainwater i s  supplied from three large tanks 
(Plates 39 and 40). The company sa l t s  and d r i e s  fish f o r  export, cuts mangrove 
for  timber, collects a limited number of giant tor toises fo r  export, and also 
takes the green turtle, maintaining a la rge  turtle pen on the northernmost island 
in West Channels. Aldabra is leased jointly with Cosmoledo and Assumption. 
No guano o r  phosphate ever  seems to have been exported from Aldabra. 
F r y e r  (1911, 407) drew attention to the presenceof phosphate, and Baker (1963, 
107-110) estimated reserves  a t  about 1000 tons, beinguneconomic to work. He 
found no evidence of rich guano previously reportedin the Cinq Cases area. 
One of the Western Channels, Passes  Lanier,  may, however, be named after 
one of the leading Seychelles guano companies. 
The fur ther  prospects for  economic development a t  Aldabra seem unpromis- 
ing. The a r e a s  of sandy soil suitable f o r  coconuts a r e  very limited, and there 
is no possibility of extending the coconut industry. The Mauritius-Seychelles 
F isher ies  Survey gave a disappointing picture of Aldabra's fish potential (Wheeler 
1953a). It was estimated that eight men could produce 70 tons, a t  f i rs t ,  of f r e sh  
fish a year  from the lagoon, falling to a steady figure of 12-16 tons per  annum; 
and that eighty men could produce 460 tons per  annum outside the atoll. The 
possibility of exporting orchella a s  an organic dyestuff (Dupont 1907, 28-29) 
collapsed with the development of synthetic dyes. 
2. Introduced Animals and Plants 
In 1966 the introduced mammals of Aldabra included goats, dogs, cats, r a t s  
and mice. Voeltzkow recorded the presence of a fe ra l  cat, though his narrative 
does not make c lear  where i t  was seen (Voeltzkow 1897, 66), and also r a t s  and 
mice, in 1895 (Lorenz-Liburnau 1899). Abbott (1893, 762) and F r y e r  (1911, 417) 
considered the f e ra l  ca ts  to be confined to South Island, and though an unidenti- 
fied observer  in 1906 considered they were "everywhere" he only saw them on 
South Island (Anon. 1920, Ch. 9, 5-7). The ca ts  a r e  said (Anon. 1920, Ch. 9, 7) to 
have been introduced by James  Spurs to control ra t s ,  and that Spurs rejected 
the suggestion that only one sex  should be introduced. Both Abbott and F rye r  
stated that the fe ra l  ca ts  had exterminated theflightless rai l ,  a t  least  in the 
Takamaka area.  Two were seen near Frigate Pool, a t  the eas t  end of South 
Island, in 1966. F e r a l  dogs were heard barking on South Island in 1966, but were  
not seen; they a r e  reported to number only two, and to he of the same sex. 
Goats were introduced by James  Spurs when lessee  in 1890. Griffith (in 
Fairfield and others  1893, 154) s tates  that they were brought from Cosmoledo, 
but we have found no other reference togoats on that atoll. According to Dupont 
(1907, 13, 22) they were brought f rom Assumption, where they had been intro- 
duced by a whaler in c. 1887, possibly from Europa Island in the Mozambique 
Channel (Abbott 1893, 763). According to Dupont, they were soon exterminated 
on West Island (Dupont 1907, 22), though they were again reported there in 1905 
(Anon. 1920, Ch. 9, 2). They became fera l  on South Island. Travis  (1959, 178- 
181) describes considerable herds  on the southern dunes, but in 1966 only one 
small group of four individuals was seen on two occasions a t  the eas t  end of 
South Island. Prosper i  (1957, 198) records goats at the eas t  end of Middle Island, 
but this must be an e r r o r ,  a s  they a r e  not otherwise recorded there. The feral  
goats at Aldabra do not seem to have reached the s tatus of major pests  that 
they have become on other islands, and do not appear to represent  a major  
threat to tortoise food supplies. 
Rats a r e  thought to be more  active predators; they probably feed on frigate 
and booby eggs and young, and possibly also on tortoise eggs and young, though 
not to a serious extent. Domestic fowl a r e  also kept a t  West Island, and have 
become feral .  
Introduced plants include such cultivated species a s  maize, cotton, sisal,  and 
probably coconuts, together with common weeds such a s  S t a c h y t a e ,  but 
these a r e  all  limited to the neighbourhood of the settlement and cultivated 
areas.  
Because of their poverty in genera and species, island ecosystems nor- 
mally have low ecological inert ia  and a r e  specially liable to catastrophic in- 
vasion by animals and plants (Elton 1958). It is therefore remarkable that the 
effects of introduced species a t  Aldabra have so f a r  been s o  limited; though the 
possible effects of the spread  of the major predators  and competitors already 
present on South Island to other parts  of the atoll must  not be ignored. It is 
fortunate that the introduction of rabbits, hares,and cattle--all potential herbi- 
vore competitors for  the tortoises--which was proposed byDupont (1907, 32) to 
augment food supplies, never took place. 
3. Exploitation and Conservation 
The scientific importance of Aldahra was not realised until the lat ter  par t  of 
the nineteenth century, af ter  the disappearance of tortoises and r a r e  land birds 
f rom the Mascarene Islands. When the Government of Mauritius f i r s t  proposed 
to lease the islands for  woodcutting, there was a considerable outcry, and sev- 
e r a l  species a r e  now protected by legislation. "Legislationis one thing," how- 
ever, "and the enforcement of laws against fishermen on the open s e a  o r  i n  
uninhabited places is another" (Griffith, in Spurs 1892, 44). 
(a) Tovtois es 
Active conservation of the tortoises was begun by the let ter  sent to the Gov- 
e rnor  of Mauritius in 1874 by agroupof naturalists which included Charles  
Darwin, Joseph Hooker and Richard Owen (Gunther 1877, 20-21). when i t  was 
f i r s t  proposed to establish a woodcutting colony on the atoll. Part icular  concern 
was expressed over the "imminent extermination of theGigantic Land-Tortoises 
of the Mascarenes". Even a t  that time i t  could be stated that "Aldabra is now 
the only locality where the last remains of this animal form a r e  known to exist 
in a s ta te  of nature", and i t  was argued that 
"The rescue and protection of these animals is, however, recommended. . . 
l ess  on account of their utility . . . than on account of the great  scientific 
interest  attached to them. With the exception of a s imi lar  tortoise in the 
Galapagos Islands (now also fas t  disappearing), that of the Mascarenes is the 
only surviving link reminding us of those s t i l l  more gigantic fo rms  which 
once inhabited the continent of India i napas t  geological age. . . . It flourished 
with the Dodo and Solitaire; and whilst i t  is a matter  of lasting regret  that 
not even a few individuals of these curious birds should have had a chance 
of surviving the lawless and disturbed conditions of past centuries, it is con- 
fidently hoped that the present Government and people . . . will find a means 
of saving the last  examples of a contemporary of the Dodo and Solitaire" 
(quoted in Gunther 1877, 20-21). 
Leasing of exploitation rights on the islands proceeded, however, without legis- 
lation to protect the tortoises. For  a number of years  they were  conserved by 
the private philanthropy of the Hon. Walter (IaterLord) Rothschild, who en- 
tered into an agreement by which he paid one half of the lessee 's  annual rent  
(Rs. 1500 per  annum of a total rent  of Rs. 3000) on condition that the tortoises 
were  rigidly protected. This agreement was f i r s t  made with Mess r s  Baty, 
Borgne and Co., the lessees  in 1900-04, and was later  t ransferred to their 
successors  (Dupont 1907, 15-16). 
No protective legislation covering the tortoises was passed until recently 
(Lane 1953a, 1953b), although the species could have been scheduled (but was 
not) under the Wild Birds and Animals (Protection) Ordinance of 1906. Action 
was eventually taken (Proclamation 4 of 1961) under the Customs Management 
Ordinance, to prohibit the export of the giant tortoise f rom the Seychelles with- 
out the written authorisation of the Colonial Secretary (Statutory Instrument 7, 
1961: Seychelles Gazette, Supplement, 13 February 1961, p. 40). There is ap- 
parently no legislation concerning the taking of tortoises f rom Aldabra, o r  the 
killing of tortoise on the atoll. The Governor of the Seychelles has powers, how- 
ever, to "make regulations for  the protection of wild animals" under the re- 
vised Ordinance to provide for  the Protection of Wild Animals and Birds, No. 
37 of 1961 (Seychelles Gazette, Supplement, 26 December 1961, pp. 163-165). 
Under the t e rms  of the 1955 commercial lease (see Section 6(3)(d)), the lessee  
is required to protect the tortoises and not to interfere with them. The West 
Island se t t le rs  kill tor toise occasionally fo r  food, and though the total annual 
loss  may be quite high, i t  is by no means catastrophic. If any future develop- 
ment of Aldabra were to exclude tortoises f rom the platin, however, there would 
certainly be a considerable fall in numbers, and further  protective legislation 
would be necessary. 
(b) Tuvtles 
Commercial exploitation of the turtles, mostly the green, began about 1906, 
though they had been taken less  systematically for  severa l  years  before this. 
Fryer (1910, 260) regretted their "wasteful slaughter", which even then (1908- 
09) was resulting in a considerable decline in numbers (Fryer 1911, 421-423). 
In particular the practice of turning females on the beaches when they came 
ashore to lay had greater long-term effects on the population than that of 
harpooning males a t  sea, particularly when carried out early in the season. 
Hornell, commissioned to enquire into the state of the Seychelles turtle in- 
dustry, reported that at Aldabra "the policy of the lessees cannot but lead to an 
early extinction of the trade" (Hornell 1927, 37). At this t ime the total number 
of green turtle taken from the islands of Aldabra, Assumption and Cosmoledo 
was of the order of 3000-4000 per annum. Hornell made specific recommen- 
dations for conservation and for  the revision of original conservation legislation 
which dated from the beginning of thecentury (Ordinances 16 of 1901 and 2 of 
1904). The new legislation (Ordinances 5 of 1925 and 5 of 1929) specified mini- 
mum sizes for both green and hawkshill turtles taken, prohibited the taking of 
buried eggs, barred the use of torches at night and the taking of turtle within 
1000 metres of the high water line, and laid down control procedures (Lane 
1953a, 114-120; 1953b, 195-200). The major recommendation whichwas not 
adopted was that for a close season from December 1 to the last day of Feb- 
ruary, during which no turtle might be caken. Hornell also proposed the control, 
at Aldabra, of frigate birds, herons, and the ibis, all of which (hut especially 
the frigate) were said to kill large numbers of newly hatched turtle. Dupont 
(1907, 29) had previously proposed the extermination of frigates and herons by 
shooting and poisoning, for  the same  purpose, butneither proposal was for- 
tunately accepted. 
In spite of the legislation of 1925 and 1929, the numbers of green turtles 
continued to decline, and by the time of the Mauritius-Seychelles Fisheries 
Survey the number taken annually was less  than 1500. Following this survey, 
Wheeler (195333) again put forward Hornell's close-season recommendations, 
and these were adopted in  Government Notice 452 of 1948. Under this, the close 
season, during which no green turtle might be taken at Aldabra o r  Cosmoledo, 
was defined from December 1 to the last day of February; and it was further 
made illegal to turn turtle on the beaches between March 1 and May 31 (Lane 
1953a, 200-201). This last provision was designed to protect females during 
the earlier of their repeated egg-laying visits. Minor changes in this legisla- 
tion were made by Ordinance 22 of 1957 (Seychelles Gazette, Supplement, 23 
December 1957, pp. 64-66). 
There has been no detailed work on theAldabra turtles since the Fisheries 
Survey, but numbers of the green turtle continueto decline, and those of the 
hawksbill a re  now very low. A further revision of the Turtles Ordinance was 
made by the Female Turtles Protection Regulations, 1962 (Seychelles Gazette, 
Supplement, 23 July 1962, p. 44), in which the close season, during which i t  is 
made illegal to catch, kill, harpoon o r  otherwise take female turtles, is ex- 
tended from December 1 to March 31. This originally applied to both the green 
turtle and the hawksbill on Aldabra, Cosmoledo, Farquhar, Providence and 
other islands; but the hawksbill was deleted in revised regulations later the 
same year (Female Turtles Protection (no. 2) Regulations, 1962: Seychelles 
Gazette, Supplement, 1 October 1962, p. 68). Subsequently, the use of under- 
water guns o r  other underwater equipment for taking the hawksbill was pro- 
hibited (The Hawksbill Turtle Protection Regulations 1963: Seychelles Gazette, 
Supplement, 3 June 1963, p. 48); and this provision specific to the hawksbill was 
later  revoked and added a s  an amendment to the Turt les  Ordinance, prohibiting 
the use of underwater equipment fo r  either thegreen turtle o r  the hawksbill 
(Ordinance 1 of 1964: Seychelles Gazette, Supplement, 9 March 1964, pp. 9-11). 
Under the t e rms  of the 1955 commerciallease,not more than 500 green 
turt les  per annum may he taken on o r  within three miles of Aldabra, and none 
a t  all  a t  Cosmoledo and Assumption, without written permission from the Sey- 
chelles Government, and no turtle eggs may be taken on any of the islands 
(Article 9(a)). 
Birds have long been protected in the Seychelles under the Wild Birds and 
Animals (Protection) Ordinance of 8 December 1906 and the Plumage Birds 
(Exportation) Ordinance of 21 February 1914. The former  gave the Governor of 
the Seychelles powers to prohibit the killing o r  taking of any scheduled bird, o r  
the taking of i ts  eggs, with exceptions permitted for  scientific o r  natural history 
purposes (Lane 1953a, 124-125). The schedule of birds thus protected (Wild 
Birds and Animals Protection Ordinance of 21 June 1941) included the following 
species a t  Aldabra (nomenclature revised; original nomenclature given in 
brackets): 
Phoenicopterus ruber  roseus (Phoeniconaias minor) 
Threskiornis aethiopica abbotti 
-- -
(ibis ahbotti) 
Phaethon lepturus lepturus 
- -- 
(Phaethon lepturus) 
(Lane 1953b, 204-205). The schedule of birds protected underthe Plumage 
Birds (Exportation) Ordinance includes (by Proclamations 5 of 1914 and 1 of 
1947), for  Aldabra, a l l  the above except Phaethon lepturus lepturus, together 
with: 
Phaethon rubricauda rubricauda (l'haethon ruhricauda) 
Streptopelia picturata aldabrana -- (T-r aldabrana) 
Dicrurus aldahranus (Buchanga aldabrana) 
Zosterops maderaspatana aldabrensis (Zosterops -- aldabrensis) 
Caprimulgus madagascariensis (Caprimulgus aldabrensis) 
aldabrensis 
Centropus toulou - .  insularis (Centropus insularis)  
Foudia eminentissima aldabrana (Foudia aldabrana) 
Nectarinia sovimanga aldabrensis (Cinnyris aldahrensis) 
(Lane 1953b, 193). All these protected birds a r e  land birds except for  the 
tropicbirds, the sacred  ibis, and the flamingo. The Bird's Egg Ordinance of 
1933, designed to protect the Sooty Te rn  in the Seychelles, and subsequently ex- 
tended and many t imes revised (chiefly hy the Collection of Birds' Eggs Regula- 
tions, 1957, and the Collection of Birds' Eggs Regulations, 1962: Seychelles 
Gazette, Supplement, 17 May 1957, pp. 25-26, and 4 June 1962, pp. 32-34), has 
never extended to Aldabra. 
In 1961 the Wild Birds and Animals (Protection) Ordinance and the Plumage 
Birds (Exportation) Ordinance, under which all the above birds were  protected, 
were  both revoked, and replaced by a single Ordinance to provide fo r  the Pro-  
tection of Wild Animals and Birds (Ordinance 37 of 1961: Seychelles Gazette, 
Supplement, 26 December 1961, pp. 163-165). Thisordinance gives the Governor 
in Council power to "make regulations for  the protection of wild animals and 
birds". In addition to the two ea r l i e r  ordinances, all the proclamations under 
them were also revoked; s o  that presumably new schedules of animals and birds 
protected must be issued.* 
IJnder the t e rms  of the 1955 commercial  lease, no birds'  eggs may be com- 
mercially exploited, and the only birds whichcanbe taken a r e  crows and poultry. 
(d) Consevvation Pvospects 
Following the Darwin-Hooker appeal over  the tortoises, and the gradual de- 
velopment of protective legislation for  tortoises, turtles andbirds, commercial  
exploitation of Aldabra on a sma l l  sca le  became accepted. The next major issue 
was in the early 1950s, when it was  proposed to set t le  1200 Seychellois, dis- 
charged from the Army Pioneer Corps in the Middle East, on the atoll, the last  
commercial  lease having lapsed in  1945 and not having been renewed. Fosberg 
(1954) prepared a memorandum on the scientific importance of Aldabra, and the 
inadvisability of this step, and the proposal wasdropped, probably a s  much on 
account of the inhospitable environment a s  for  scientific reasons. 
Following the visit of the Calypso to Aldahra in 1954, Commander J.-Y. 
Cousteau became interested in the conservation of the atoll, a t  a time when the 
commercial lease  was about to be renewed. Cousteau's proposal to lease  the 
atoll "as a wildlife sanctuary and . . . tropical research  centreon an island 
almost uncontaminated by man" (Cousteau 1963, 149) was rejected, but his  pub- 
licity in London (Cousteau 1963, and also Cousteau 1959) led to important conser- 
vation clauses in the commercial lease concluded between the Seychelles Govern- 
ment and M r  H. Savy, of Mah6, on 2 and 5 February 1955. Proposals fo r  turning 
Aldabra into a commercial breeding ground for  Chinese ducks were also rejected. 
The lease  i s  f o r  30 years, with an option on a further  period of 20 years. Article 5 
of the lease states: 
"That the lessee shall respect  South Island in the atoll of Aldabra a s  a nature 
reserve.  Without prejudice to the generality of the implications of this con- 
dition the lessee hereby covenants:-- 
(a) That there shall be no settlement on South Island. 
(b) That he shall protect all animal  life on South Island. 
(c) That he shall not introduce any new animal o r  plant on South Island. 
*"The Cornmissioner, British Indian Ocean Territory, states that although the Protection of 
Wild Birds and Animals Ordinance was published in 1961, it  did not come into force in the Sey- 
chelles until 1966, i.e., after the formation of the British Indian Ocean Terr i tory on 8 November 
1965. Hence it  does not apply to Aldabra, where the Wild Birds and Animals (Protection) Ordi- 
nance (Cap. 24) and the Plumage Birds (Yxportltion) Ordinance (Cap. 19) together with the Regu- 
lations made under these Ordinances a r e  stili in force. The schedules of protected birds listed in 
Chapter 2 consequently still apply to Aldabra." 
(d) That he shall not exploit any of the resources of the said South Island ex- 
cept mangrove which he shall have the right to cut and remove." 
Article 6 allows "unrestricted exploitation" of coconuts, mangroves, seaweed, 
shel l  fish, sea  slugs, fish, goats, c rows and poultry. Quarrying of stone (Article 
9(b)) and clearing of woodland (Article 10) a r e  restricted; clearing by f i re  is 
prohibited without permission (Art icle  11). The total resident population is not 
to exceed 200 persons without permission (Article 17). 
Articles 12, 13 and 14 add further  conservation measures: 
"12. That the lessee  shall be the guardian and protector of al l  wild life and 
al l  the resources of the Islands and of the surrounding seas.  The lessee shall 
ensure to the best of his ability that, save a s  provided in this lease, no wild 
birds, tortoises o r  other animals a r e  molested, deprived of their proper 
sustenance, disturbed, taken o r  killed by any person not holding the express 
permission in writing of the lessor. 
13. That apart f rom the restr icted and unrestricted exploitation detailed 
above the lessee shall in no way exploitor permit the exploitation of the 
animal and mineral resources of the Islands o r  surrounding seas  without the 
express permission in writing of the lessor. 
14. That the lessee shall not exploit for  export o r  otherwise birds' eggs 
without the express permission in writing of the lessor." 
An important clause, Article 16, gave the Government of the Seychelles powers 
to establish a research  station on the atoll: 
"16. That the lessor  r e se rves  the r ight  fo r  the Government of Seychelles o r  
fo r  any person, body of persons corporate o r  incorporate, sponsored by the 
Government of Seychelles, to establish on any of the Islands, scientific r e -  
search  stations fo r  the purposes of zoological, oceanographicand other scien- 
tific researches.  The lessee shal l  be hound to grant, f r ee  of any charge, a l l  
the reasonable facilities on the Islands fo r  the establishment of the said r e -  
s ea rch  stations and shall do everything in his power to promote and facilitate 
any researches that may be ca r r i ed  out." 
Finally, Article 21 gives the Government of Seychellespower to resume posses- 
sion of the islands a t  any time fo r  a "public purpose", defined to include "the 
building of lighthouses, Police Stations, o r  other public buildings and al l  Ad- 
miralty and War Department requirements". 
In 1964 it became known that the Ministry of Defence was considering the 
establishment of defence facilities, including an airfield, a t  Aldabra. This pro- 
posal, following discussions between the Ministry of Defence and the Royal 
Society, led to scientific participation in the joint B.B.C.-Ministry of Defence 
expedition in 1966, the formulation of preliminary conservation policies (Stod- 
da r t  1966b), and to the planning of a programme of further scientific work on 
the atoll, beginning with the Royal Society Expedition to Aldabra 1967-68. 
The Ministry of Defence interest  a l so  led to a change in the status of Aldabra 
and certain other islands. Since 1903, when the Seychelles administration be- 
came independent of that of Mauritius, Aldabra has been administered f rom the 
Seychelles a s  part  of that colony, and in fact had been s o  administered infor- 
mally s ince the 1880s. By the British Indian Ocean Terri tory Order in Council, 
1965, however, Aldabra was detached f rom the Colony of Seychelles to form, 
with Farquhar, Desroches, and the islands of the Chagos Archipelago, a new 
Terri tory.  Under the British Indian Ocean Terri tory Order 1965 and the 
British Indian Ocean Terri tory Royal Instructions 1965 (Seychelles Gazette, 
Supplement, 13 December 1965, pp. 184-193), the Terr i tory is to he governed 
by a Commissioner, with powers of legislation, and laws in force in the in- 
dividual islands a t  the time of the formation of the Terr i tory a r e  to continue to 
he valid. The f i r s t  Commissioner of the B.I.O.T. is the Governor of the Sey- 
chelles; and the laws of the Seychelles will continue to apply and to he enforced 
in the Territory, including Aldahra (Ordinance to provide for  the exercise of 
powers and duties in Seychelles in respect  of the British Indian Ocean Terr i -  
tory, for  the enforcement of process and theexecution of judgment in Seychel- 
l e s  issued o r  given by Courts i n  the exercise of their jurisdiction in respect  of 
the British Indian Ocean Terri tory,  Ordinance 27 of 1965: Seychelles Gazette, 
Supplement, 20 December 1965, pp. 131-132). All theconservation measures s o  
f a r  discussed remain in force, therefore, in spite of the change in the s tatus of 
Aldabra. A further  measure which also remains in force is the designation of 
West Island (Picard) a s  a port f o r  the purposes of Customs laws, under Procla- 
mation 11 of 1956 (Seychelles Gazette, Supplement, 8 October 1956). 
7. A NOTE ON PLACE NAMES 
Place-name usage on Aldabra is complicated by thefact that the atoll is a 
British possession, but most of the place names were given by French-speaking 
people, and the local inhabitants speak a French patois. English names have 
been given to some of the largeris lands,  and a r e  to some extent used locally, 
hut most of the smal le r  topographic features only have French names, In a t  
least  one case  (Johnny Channel) a topographic feature has an English but no 
French name. It is not therefore possible to adhere to a toponymy either com- 
pletely English o r  completely French. A further  complication is added by the 
fact that some features have been named by passing vessels  o r  occasional 
visitors, the name has had brief usage andhas appeared in the literature, hut 
is no longer used locally and may he considered dead. 
A basis for  accepted toponymy is given by the two Department of Overseas 
Surveys 1:25,000 map sheets of Aldabra, which where possible give precedence 
to English names adding the French i n  brackets, and otherwise using French 
names where no English name is availahle. This usage is generally followed in 
these papers, with a few exceptions mentioned below. Where a choice of names 
exists, regard should be given to established usage, and a s  a further principle, 
new names should not be unnecessarily introduced. 
1. Main islands 
Polymnie 
No alternative name i s  known. The name i s  presumably of French origin, 
and the cor rec t  version is thus I le  Polymnie, though the D.O.S. uses Polymnie 
Island. 
Middle Island 
This name is used on the 1878 Admiralty chart, by F rye r  (1911), and on the 
D.O.S. map, all  with the subsidiary fo rm Ile Malabar o r  Malabar Island. 
Abbott (1893) uses "North o r  Middle Island" and "Ile Nord". The usage of 
of North Island has come into the zoological l i terature through Rothschild 
(1915). Middle Island is accepted. 
South Island 
This name is used on the 1878 Admiralty chart  and by F r y e r  (1911) (who 
uses  "Main o r  South Island"), and also on the D.O.S. map. Abbott (1893) uses 
Grande Terre.  South Island is accepted. 
West  Island 
This name i s  used on the 1878 Admiralty chart, by F rye r  (1911), and on the 
D.O.S. map. The 1878 chart  and F rye r  quote a s  a subsidiary name Ile Picard, 
and the D.O.S. map uses the hybrid Picard Island. These names predate the 
existence of the settlement, and hence there  is no case  for  using the name 
Settlement Island. West Island is accepted. 
2. Lagoon islands 
Ile Espri t  
Ile Esprit  appears  on the 1878 Admiralty chart, in F rye r  (1911), and on the 
D.O.S. map a s  subsidiary to "Euphrates Island". Espri thas priority and is 
used locally: the name Euphrates derives,  according to Findlay (1882), f rom 
the visit of the ship Euphrates en route f rom London to Karachi in 1862. This 
does not seem a sufficient basis to establish the name. Abbott (1893) uses Ile 
Sepoy, which must be a misunderstanding o r  misprint. Ile Sylvestre is used 
fo r  the small  adjacent island on the 1878 chart,  by F ryeZl911) ,  and on the 
D.O.S. map, and has no English alternative name. Esprit  and Sylvestre a r e  
accepted here. 
Ile Michel 
Ile Michel appears  on the 1878 Admiralty chart, in F r y e r  (19111, and on the 
D.O.S. map a s  subsidiary to "Cocoanut Island". Cocoanut Island was introduced 
by Wharton during the Fawn survey, when coconut t r ee s  were  planted there; 
and Michel has precedence and is used locally. Abbott (1893) also uses Michel. 
Michel is used here. 
Other i s  lands 
The D.O.S. map gives French names to a number of other lagoon islands, 
all  of which a r e  acceptable and are  used here. The name Ile Magnan should be 
used for  the largest  island in West channels, and appears on the 1878 chart. 
3. Channels 
The names Main Channel, East  Channel, and West o r  Western Channels a r e  
used on the D.O.S. map and the 1878 chart,  with the subsidiary names of Grande 
Passe,  Passe  Houareau, and (in the 1878 chart) Pas ses  I,anier, respectively. 
This usage is followed here. The D.O.S. map gives French names to the minor 
channels of West Channels (Passe  Femme, Passe  du Bois, Passe  Mannian, 
Passe  Grabeau), and these a r e  also accepted apart  f rom Mannian, which is 
properly Magnan. Johnny Channel has no French equivalent. 
4. Land names 
The D.O.S. map gives a number of French names fo r  dunes, beaches and 
headlands, and a l l  a r e  accepted. On South Island i t  is useful to add Takamaka 
(1878 chart), Wilson's Well (Dupont 1907),and Abbott's Creek (1878 chart  and 
F r y e r  1911). Bras Takamaka of the D.O.S. map is preferred to the East Bay 
of F rye r  (1911). The names Camp Frigate, Ile Verte, and Couroupa a r e  used 
by F rye r  (1911) and may he usefully retained. Couroupa is also used by Dupont 
(1907), and is apparently the s a m e  as theD.0.S. feature named ~ n s e  Tamarind, 
though this is in a different location f rom Fryer ' s  (1911) Tamarind Point: this 
should he resolved in the field. Fryer ' s  (1911) location named Camp Frigate is 
named "Opark" on the D.O.S. map of Middle Island. 
Two further  names a r e  proposed he re  for  pools on the platin of South Island: 
Frigate Pool, a la rge  pool used by diving frigate birds, and Flamingo Pool, the 
largest  freshwater pool on the island, a name in local usage though we have 
not been able to discover any evidence of flamingoes using it. These names a r e  
located in Figure 3. 
Chapter  3 
SUMMARY OF THE ECOLOGY OF CORAL ISLANDS NORTH O F  
MADAGASCAR 
(Excluding Aldabra) 
D. R. Stoddart 
Department of Geography, Cambridge University 
1. Assumption 
2. Astove 
3. Gloriosa 
4. Cosmoledo 
5. Farquhar (Joao de Nova) 
6. St P ie r re  
7. Providence 
Atoll Research Bulletin No. 118: pp. 53-61 November 15, 1967 
The need to establish the ecological s tatus of Aldabra among the islands 
of the southwest Indian Ocean has required the collection of information on 
several  sea-level and elevated atolls and reef-islands in this area, and in 
particular on the islands between Aldabra in the west and Providence Bank 
in the eas t  (Figure 6). Seven islands aye included: Assumption, Astove, 
Cloriosa, Cosmoledo, Farquhar, St Pierre,  and Providence. Much of the in- 
formation on the ecology of these islands is very old, dating from the cruise 
of the Alert in 1882, the visit by ~ h b o t t  in 1892-93, by Voeltzkow in 1895, 
the Valhalla in 1906, the Percy Sladen Expedition in 1905, by F r y e r  in 1908 
and by Dupont, Thomasset and others early in this century. Much of the infor- 
mation on particular groups of animals is scat tered through the Percy Sladen 
Expedition Reports and other lists, and has never been brought together fo r  
each island. Furthermore, most  of the collections were made in the period 
Figure 6.--Islands and Bathymetry of the South West Indian Ocean 
preceding the mining of guano, during which the natural vegetation was de- 
stroyed on several  islands and certain birds and other animals became ex- 
tinct. In more recent years, we have the observations made by Vesey-Fitz- 
Gerald on the vegetation and the birds in 1937, and the largely geological 
observations of Baker and Piggott in 1960-61. The Bristol Seychelles Expe- 
dition spent some hours ashore on Cosmoledo Atoll (Menai Island) on 9 
November 1964 and on Assumption on 10 November 1964. The following year 
R. Gaymer, of that expedition, made a short visit to Cosmoledo on 1 October 
1965 and to Assumption on 3 October 1965. I am grateful to R. Gaymer for 
sending me a copy of his observations on these islands. 
Because the information on these islands is so scattered, the salient fea- 
tures of the ecology of each of the seven islands o r  atolls listed a r e  here sum- 
marized, with reference particularly to the vegetation, the reptiles, and the 
birds. In preparing this summary, lists were compiled of the plants collected 
o r  recorded from each island, based on published accounts, particularly those 
of Dupont (1907) and Hemsley (19191, and use was made of the lists of birds 
by Watson, Zusi and Storer (1963). For the information on insects I have re-  
lied on the summary by Scott (1936) and no special search has been made of 
the papers in  the Percy Sladen Expedition Reports. The most important gen- 
eral  sources a r e  Coppinger (1883), Dupont (1907), Fryer  (1911), Vesey- 
FitzGerald (1940, 1941, 1942), Watson, Zusi and Storer (1963), and Baker 
(1963). The summary account of each island does not contain citations for 
each statement, but a list of the more important references, less important 
references, and maps is appended to each: full citations a r e  given in the 
"Bibliography of Aldabra" in this Bulletin. 
This summary does not treat  the Amirantes and Desroches, Cargados 
Carajos, Agalega, o r  Tromelin. 
1. ASSUMPTION g046's., 46O31'E. 
Assumption is an elevated reef island 20 miles south of Aldabra, 3.75 
miles long and 0.3-1.0 miles wide. The deeply dissected reef rock r ises  to 
20 f t  above sea level, with dunes on the east and south sides rising to 90 
feet. Early in the century the island was wooded in the west and southwest, 
and the centre was only thinly vegetated. The vegetation resembled that of 
Aldabra, and 68 species of flowering plants have been recorded, three of 
them endemic (Panicum assumptionis, Eriochlea subulifera, Stenotaphrum 
clavigerum), The dunes a r e  covered with Sporobolus and clumps of Sclero- 
dactylon, with patches of -a, Scaevola and Tournefortia. The centre of 
the island had a few Hibiscus bushes, and coconuts a r e  planted on sand along 
the west shore. The rest  of the island has been stripped of vegetation during 
guano-digging, and there a r e  now only a few stunted bushes in holes and pits, 
the ground being covered with Plumbago aphylla. Some Casuarina have been 
planted on the west coast. No mangroves a r e  recorded. 
Tortoises formerly existed here, and Fryer found their remains. There 
is a skink Ablepharus boutonii, and two geckos, Phelsuma abbotti abbotti and 
--
Hemidactylus mercatorius. 65 species of insects a r e  recorded. Birgus latro 
was common in  1906. Marine turtles formerly nested here in large numbers, 
but only a few a r e  reported to do so now. 
Large numbers of boobies and terns formerly bred on the island, but have 
disappeared a s  a result of mining operations. Abbott's Booby, Sula abbotti, is 
now extinct on Assumption and is found only on Christmas Island. Vesey- 
FitzGerald gives the date of its disappearance a s  1926. Sea and shore birds 
recorded a s  breeding on Assumption a r e  Sula abbotti (extinct), Butorides 
striatus, Ardea cinerea, Egretta garzetta dimorpha, (which may also be ex- 
---- 
tinct), and possibly Sula sula. Others recorded from the island a r e  =a 
9 3 1 8 9 4 a .  became ex- 
- .  
tinct between 1906 and 1937. The coucal and turtledove may also have disap- 
peared. Gaymer recorded -- Corvus albus in 1965. 
Guano reserves a r e  the largest in the western Indian Ocean: 161,000 
tons were exported during 1926-1945, and Baker estimates the remaining re -  
serves at 160,000 tons. Mining ceased in 1945, but has started again since 
1955; a mechanical crusher and light railway have been installed. Goats were 
introduced in early 1887 by a whaler, became feral, and were later used to 
colonise Aldabra; Abbott states that they were brought from Europa Island in 
the Mozambique Channel. Nicoll found twenty in 1906, but according to Gaymex 
they no longer exist. Nicoll also found numerous ra ts  which were threatening 
to eliminate some of the r a r e r  birds. 
Main references: Abbott 1893, 763; Baker 1963, 101-106, 124-126; Dupont 
1907, 12-13; Fryer  1911, 431-433; Nicoll 1906; Nicoll 1908, 107-113; Ridgway 
1895, 520-523; Vesey-FitzGerald 1940; Vesey-FitzGerald 1941; Vesey-Fitz- 
Gerald 1942, 12-13; Watson, Zusi and Storer 1963. 
Additional references: Honegger 1966b; Ridgway 1893; Ridgway 1894b; 
Vesey-FitzGerald and Parker 1947. 
Map: Baker 1963, 102. 
2. ASTOVE 10?06'S., 47O45'E. 
Astove is an elevated coral atoll 3.5 miles long and 2.5 miles wide, con- 
sisting of a reefrock r im 15 feet high, with sand dunes 45-50 feet high on the 
east coast. According to Baker reefrock covers 583 and sand 642 acres. The 
lagoon averages 3-4 feet in depth, with a maximum of 10 feet, and the en- 
trance dries a t  low water. The fringing reef is 200 yards wide. 
The dunes a r e  covered with Suriana on the windward side, and with 
Scaevola and Tournefortia to leeward. Lagoonward of the dunes, champignon 
is covered with Pemphis thicket. The lagoon is filled with fine sediment, and 
is ringed with scattered Avicennia trees, but otherwise there is no man- 
grove. On the western lagoon shore, beach ridges a r e  colonised by Sporoho- 
1 2 ,  and planted with coconuts and Casuarina. Pemphis grows on bare reef- 
rock, and Scaevola and Tournefortia on sand. The sea  coast on the leeward 
-
side has a thicket of Suriana, Scaevola and Tournefortia. A deciduous scrub 
covers the surface on the wider parts of the eastern side, with frequent 
Pisonia trees. 59 species of plants a r e  recorded from Astove. 
Tortoises formerly occurred here, according to Rothschild, and Fryer  re- 
ports the finding of possible remains. Other reptiles include Phelsuma astriata 
astovei, Hemidactylus mercatorius, and possibly Ablepharus boutonii. Fryer  
also found that insects were numerous (27 species a r e  recorded) and butter- 
flies especially common. The land birds include Nectarinia sp., Zosterops 
maderaspatana, and a flightless rail, Dryolimnas cuvieri. Abbott reported 
the rai l  from hearsay, but it  was probably extinct by 1906. Large numbers of 
Egretta garzetta have recently been recorded, together with Ardea cinerea 
and Butorides striatus. There a r e  records of Bubulcus ibis ibis, Thalasseus 
bergii thalassina and possibly Demiegretta asha. -- Sula -. sula may be the only 
breeding sea  bird; Corvus albus and Cisticola cherina have appeared; and 
--
there is a record of Hydroprogne caspia. 
Guano is found on the west side, and has been mined since 1927. 70,000 
tons have been reported, and 5000 tons a r e  left, according to Baker. Most of 
the native vegetation in the guano area has disappeared, though some Pisonia 
grandis and occasional Sideroxylon inerme remain. It has been replaced by 
-
Plumbago aphylla, with Dactyloctenium pilosum and Stachytarpheta indica; 
Agave and Gossypium a r e  also found. Coconuts a r e  grown on the west side, 
-
though not very successfully, and maize has been grown in the dunes. 
Main references: Baker 1963, 92-97; Dupont 1907, 2-8; Fryer  1911, 426- 
428; Piggott 1961, 6-8; Vesey-FitzGerald 1942, 10-12; Watson, Zusi and 
Storer 1963. 
Additional references: Honegger 1966b; Vesey-FitzGerald 1940; Vesey- 
FitzGerald 1941. 
Map: Piggott 1961; Baker 1963, 94. 
3. GLORIOSA 11?34's., 45O13'E. 
The Gloriosa Islands a r e  situated 114 miles west-north-west of Mada- 
gascar, and consist of two sandy islands with a grass-covered rock between 
them. Gloriosa, the larger island, is 1.5 miles long, and has dunes 50-60 
feet high on its lee side, and a central tidal marsh which dries a t  low water. 
Ile du Lise, three miles away, is smaller ,  but has a dune 30 feet high, and 
also beachrock and conglomerate. Coppinger found a block of basalt on the 
reef, together with quartz pebbles. 
Little is known of the biota. Gloriosa has been planted with coconuts and 
the "dense growth of virgin forest" seen by Coppinger in 1882 has since been 
cleared. Ile du Lise st i l l  has woodland on it, with Ficus, Hibiscus and Scae- 
v&, and Pemphis in the central swamp. Maize used to be grown in large 
amounts on Gloriosa. Coppinger collected on the islands in 1882, and they 
were also visited by Abbott and Nicoll. According to Hemsley, Abbott found 
mangroves 50-60 feet high, hut Abbott's actual record was of sand dunes. 30 
species of plants have been recorded. 
According to Rothschild, tortoises formerly existed on Gloriosa, but no 
supporting evidence fo r  this can be found. Abbott records three small rep- 
tiles: Hemidactylus mabouia, Ablepharus gloriosus, and Zonosaurus mada- 
gascariensis. Nicoll found numerous butterflies and moths, and (on du Lise) 
Coppingtr found many spiders and hermit crabs. Both Coppinger and Nicoll 
report Birgus latro on du Lise but not on Gloriosa. Green and hawksbill 
--
turtles used to nest on Gloriosa and may still  do so. The known resident land 
birds a r e  Streptopelia picturata coppingeri, Hypsipetes madagascariensis 
e i ,  Nectarinia sovimanga sovimanga, and Zosterops maderaspatana 
maderaspatana; together with Corvus albus, which is common. Nesting sea- 
--
birds include Sula sula, Fregata sp., Sterna fuscata, and stolidus 
pileatus: large numbers of the noddies were nesting in 1906 on the rock 
between the islands. Sula abbotti may also have b red in  the past. Ph'aethon 
-- 
rubricauda rubricauda may also breed, and other species recorded a r e  
Dromas ardeola, Sterna sumatrana mathewsi, Thalasseus bergii thalas- 
----- -
sina, and Thalasseus bengalensis. Two vagrants and one migrant a r e  also 
-
recorded. The domestic fowl, Gallus gallus, has become feral. Feral  cats 
--
were common in 1893, and were reducing the numbers of birds. In 1882 
there were abundant brown ra ts  on both islands. 
Main references: Abbott 1893, 763-764; Coppinger 1883, 237-240; Cop- 
pinger 1884; Nicoll 1906, 686-692; Nicoll 1908, 100-106; Watson, Zusi and 
Storer 1963. 
Additional references: Holland 1896; Ridgway 1895, 524-526. 
Map: Guilcher and others 1965, 14, fig. 4. 
4. COSMOLEDO 9?41'S., 47'35'E. 
Cosmoledo is an atoll 9 miles long and 7 miles wide, with a lagoon 5 
miles in diameter with maximum depth of 4-1/4 fathoms. There a r e  five 
main islands and several  smaller  ones on the atoll rim, which has an aver- 
age width of one mile. Menai Island has the largest area, but Wizard Island 
o r  Grande Ile, 2 miles long, is the longest. The islands a r e  formed of up- 
lifted reefrock, much eroded, reaching 12-15 feet above sea-level, with 
large amounts of sand banked against the rocky remnants. 
At Menai Island on the west r im the seaward coast (leeward) has a dune 
scrub with Guettarda; dunes r i se  to 40 feet a t  the north end. The lagoon 
coast has mangroves 80 feet tall, with a succession of Avicennia-Bruguiera- 
Rhizophora from sea  to land. Dunes a r e  also found inside the mangrove. 
Pemphis scrub covers champignon in the centre of the island. The eastern 
islands, Polyte and Wizard, have a seaward dune fringe up to 55 feet high, 
covered with Sporobolus and Suriana on the seaward side, and with Tourne- --
fortia to leeward. Pemphis again covers the reefrock. The smaller  islands 
-
a r e  rocky, with Pemphis, Sideroxylon and Plumbago. The known flora totals 
56 species. 
Tortoises formerly existed at Cosmoledo, and Fryer  reported finding 
their fossil eggs. Other reptiles include Phelsuma abbotti menaiensis, 
Hemidactylus mercatorius, and Ablepharus boutonii. 37 species of insects 
a r e  recorded, and three species of land mollusca. There a r e  three recorded 
resident land birds: Zosterops maderaspatana maderaspatana, Nectarinia 
sovimanga buchenorum, and Dryolimnas cuvieri. Abbott reported the ex- 
istence of the rai l  from hearsay, and according to Fryer  i t  existed in  1919 on 
South Island, though he did not land there and observe it. The breeding sea 
birds a r e  ~ h a e t h o n  rubricauda rubricauda, $& dactylatra melanops, 
sula, Fregata minor, Sterna anaetbetus, Sterna fuscata, and Anous stolidus 
- -- --
pileatus. Large flocks of Egretta garzetta and small  number of Dromas 
ardeola have recently been recorded. Corvus albus is known and Cisticola 
cherina has been introduced. Both Ardea cinerea and Butorides striatus 
--
probably breed. 
Guano deposits a r e  found on North Island, and have been worked; there 
a r e  reserves of 3,500 tons. 
Maize and coconuts a r e  grown. Dupont recorded rabbits in 1906. Apart 
from notes on sea birds there is no recent information on the biota of 
Cosmoledo, though the r a i l  is thought to be extinct. 
Main references: Baker 1963, 86-92; Dupont 1907, 8-12, Fryer  1911, 
428-430; Vesey-FitzGerald 1942, 13-15; Watson, Zusi and Storer 1963. 
Additional references: Connolly 1925; Ridgway 1895; Vesey-FitzGerald 
1940; Vesey-FitzGerald 1941. 
Maps: Admiralty Chart 718 (survey of 1878); individual islands mapped 
by Baker 1963, 87, 89, 91, 93. 
5. FARQUHAR (JOAO DE NOVA) 10'10'~. , 51'7 '~.  
Farquhar is an atoll 11.5 miles long and 6.5 miles wide, maximum 
dimensions, with two main islands (South Island, North Island) on the 
eastern rim, the smal l  island of Goelette on the southeast side, and three 
small  islets on the north. The lagoon is shallow and full of patches, except 
near the east  r im, where there is a deeper basin with up to 6 fathoms and 
an entrance on the north side with 3-5 fathoms. Fryer  reports  some residual 
elevated reefrock, hut according to Baker the islands a r e  a l l  sand cays and 
there is no elevated rock. Most of North Island is less  than 10 feet above 
sea level, with dunes 5-50 feet high a t  the south end; South Island has dunes 
50-70 feet high. Goelette is low and sandy. 
Very little is known of the biota. Pemphis, Tournefortia, Scaevola, 
Casuarina and coconuts a r e  the only plants recorded. According to Roths- 
child the giant tortoise formerly occurred here, but no supporting evidence 
is known for  this. 63 species of insects a r e  known. Among the sea birds $& 
dactylatra melanops, Sterna sumatrana mathewsi, and Sterna fuscata breed on 
Goelette, and Sula sula ruhripes on South Island. m s  tenuirostis & 
=s is recorded roosting but not breeding. There is a single native land 
bird, Foudia madagascariensis, which is common. Gardiner states that the 
Barred Ground Dove Geopelia s t r ia ta  has been introduced and is common at  
the settlement on North Island (Grande Poste). 
There a r e  no commercial guano deposits, except for  some phosphatic 
sandstone and guano on the two main islands, but according to Piggott mining 
has disturbed the breeding colonies of terns. There a r e  settlements on both 
North and South Islands, and a jetty on the former. 
Main references: Baker 1963, 80-85; Gardiner 1907, 142-145; Gardiner 
1936, 432-433. 
Additional references: Carpenter 1916; Cockerell 1912; Edmondson 1923; 
Fleutiaux 1923; Fore1 1907; Fryer  1910; Fryer  1912; Gardiner 1906; Grou- 
velle 1913; Hampson 1920; Jordan 1939; Maulik 1931; Needham 1913; Scott 
1912; Vesey-FitzGerald 1940; Vesey-FitzGerald 1950. 
Maps: Admiralty Chart 718 (survey of 1878); Baker 1963, 81. 
6. ST PIERRE 9?19'~., 50'43'~. 
St Pierre  is a circular uplifted atoll 0.75 miles in diameter, with an area 
of 417 acres, situated 270 miles east of Aldabra and 19 miles southwest of 
Providence. The coastal cliffs r r i e  to 8-30 feet above sea-level, with no 
fringing reef, and the reefrock is deeply intersected by caves and crevices. 
Dunes 10 feet high a r e  perched on the cliffs near blowholes. The centre of 
the island is  close to sea-level, and has a small tidal pool. Physiographically 
the island resembles Assumption. 
The native vegetation consisted of Sporobolus on the dunes; Suriana and 
Tournefortia, o r  Pemphis, along the lee coast; and a scrub of Pemphis, 
Hibiscus,Pisonia and Euphorbia over the res t  of the island. Coppinger men- 
tioned a dense growth of scrubby bushes and three o r  four palms in 1882. 
25 species of land plants are recorded, and the flora was clearly like that 
of Aldabra and Assumption. Maize and tobacco have been grown. 
The fauna formerly included the giant land tortoise, according to Roths- 
child, but no direct evidence of this has been found. Apart from the Mada- 
gascar fody, Foudia madagascariensis, there a r e  no land birds, and though 
Sula sula rubripes formerly nested in large numbers, i t  does not do so now. 
--
The ecology of the island has been drastically altered by the mining of 
guano and high grade phosphate rock, which began in 1906. Between 1926 and 
1960, 151,000 tons were exported, and reserves of 10,000-15,000 tons re- 
main. The island surface is now a "maze of pits and crevices a s  a result of 
guano working", according to Baker. The mining has resulted in almost total 
destruction of the vegetation. "On the east coast a few scattered specimens 
of Pemphis bushes still  exist whilst only two extremely battered specimens 
of have been left on the centre of the island. Of the herbs which sur-  
vive on the remains of the soil, Stachytarpheta indica is the most common" 
--(Piggott 1961). Piggott also records the introduction of Gaillardia pulchella; 
together with the following exotics near the settlement: -a stramonium, 
Asystasia gangetica, Agave sp., Carica papaya, and - Musa sp. Casuarina 
has been planted a s  a windbreak, and is doing well. The guano has continued 
to be worked, and a crushing plant has been installed. 
Main references: Baker 1963, 100; Coppinger 1883, 236; Dupont 1907, 
1-2; Gardiner 1907, 148-149; Gardiner 1936, 434-435; Piggott 1961; Vesey- 
FitzGerald 1941; Vesey-FitzGerald 1942, 15; Watson, Zusi and Storer 1963, 
Map: Baker 1963, 100. 
7. PROVIDENCE g014'S., 5 1 ? 0 2 ' ~ .  
Providence Island is situated at the north end of the 25 mile long, 6 mile 
wide Providence Bank. It is 2.75 miles long and 1200 yards wide, with a reef 
platform on the west side, The island is sandy, without elevated reefrock, and 
is covered with coconuts and Casuarina. 33 species of plants a r e  recorded, 
mostly collected by Coppinger in 1882 and by Dupont. Coppinger also records 
the following cultivated plants: pawpaw, custard apple, pepper, sweet potato, 
onions, lettuce, and capsicum. 
Very little is known of the fauna. Rothschild records the former existence 
of the giant land tortoise, but on unknown authority. Coppinger found seven 
giant tortoise imported from Aldabra roaming in the woodland in 1882; and 
he also states that green turtle nest on the island in April. There a r e  22 re- 
corded species of insects. There a r e  no land birds. Sea birds breeding on the 
bank include Sterna -bergii thalasseus, Gygis alba monte, and possibly Dromas 
ardeola. Shore birds breeding on the bank include Sterna bergii thalasseus, 
Gygis alba monte, and possibly Dromas ardeola. Shore birds breeding in- 
--- 
elude Ardea cinerea, and Butorides striatus is recorded. There a r e  also nine 
records of vagrants and migrants. 
Guano reserves have been considerable, covering 147 acres  at the north 
end of the island, out of a total area of 388 acres. Between 1935 and 1949 
27,260 tons were exported, and Baker estimates reserves a t  9,000 tons. 
Cerf Islands (Banc du Sud), at the southern end of Providence Bank, is 
now a single large sand cay, with four smaller ones, while in 1905 there 
were seven small islands. Casuarina and Scaevola a r e  recorded, and coco- 
nuts and cassava a r e  said to be grown. Coppinger found only pioneer vege- 
tation and bushes in 1882. 
Main references: Baker 1963, 77-80; Coppinger 1883, 231-236; Gardiner 
1907, 146-148; Gardiner 1936, 434-435; Watson, Zusi and Storer 1963. 
Additional references: Butler 1884; Carpenter 1916; Coppinger 1884; 
Fryer 1911; Holland 1896; Line11 1897; Maulik 1931; Ridgway 1895; Schenkling 
1922; Scott 1913; Warburton 1912. 
Chapter 4 
THE B R D S  OF ALDABRA AND THEIR STATUS 
C. W. Benson 
Department of Zoology, Cambridge University 
1. Historical introduction 
2. Acknowledgements 
3. Systematic List 
(1) Land Birds 
(a) Breeding Residents 
(b) Migrants 
(c) Of Uncertain Status 
(2) Sea Birds 
4. The Land Birds: their status, origins, and trends 
of variation 
5. The Land Birds: composition of species 
6. Summary 
7. References 
Atoll Research Bulletin No. 11 8: pp. 63-1 11 November 15, 1967 
1. HISTORICAL INTRODUCTION 
Pr io r  to 1892, the one and only piece of ornithological activity pertaining 
to Aldabra seems  to have been the collecting by Commander Wharton, during 
the visit of H.M.S. Fawn to the atoll in July 1878, of two specimens of the r a i l  
Dryolimnas cuvieri aldabranus, described by Giinther (1879). They a r e  in the 
British Museum (Natural History). It is true that Sclater (1871) had described 
a turtledove a s  m r  aldabranus f rom two specimens allegedly from Aldabra, 
but a s  will be shown their origin was almost certainly in the Amirante Islands. 
Although during the course of he r  voyage in 1881-82 H.M.S. Alert visited the 
Amirantes and Gloriosa, together with Providence, Cerf Islands, $nd St P ier re ,  
she  did not visit  Aldabra o r  the nearhy islands (Coppinger 1883; Coppinger and 
others 1884). 
Dr W. L. Abbott spent three  and a half months, f rom September to Decem- 
ber  1892, on Aldabra, and made a thorough survey of the avifauna, His col- 
lections were sent  to the Smithsonian Institution, United States National 
Museum. The new forms collected were  described by Ridgway (1893, a s  
amended 1894a; 1894b), certain nests and eggs by Bendire (1894), and finally 
Ridgway (1895) gave an account of Abbott's ornithological activities in the 
western Indian Ocean generally, quoting many field observations. 
Dr A. Voeltzkow spent f rom 21 May to 21 June 1895 on Aldabra? and 
collected 59 specimens, now in the Natur-Museum und Forschungs-Institut 
Senckenberg, Frankfurt. The collection was catalogued by Berlepsch (1899). 
Voeltzkow (1917, 457-459) himself drew up a l is t  of Aldabra birds, but i t  
provided no new information. The yacht Valhalla, on which M. J. Nicoll was 
naturalist, arr ived a t  Aldabra on 13 March 1906, and stayed there three  days. 
The birds collected were reported on by Nicoll (1906), and a r e  in the British 
Museum. There is also a more  general account of the visit by Nicoll (1908). 
J. C. F. F rye r  spent f rom August 1908 to February 1909 in the archi- 
pelago--that is, including Assumption, Cosmoledo and Astove a s  well a s  Alda- 
bra. He wrote a general account of the visit, including notes on the f lora and 
fauna (F rye r  1911). These notes contain few references to birds, none of 
which were apparently collected. But F rye r  (1911, 399) s ta tes  that a bird 
collector for  the Tring Museum spent a year  there. No general account of 
this collection has been traced. There a r e  merely incidental references in 
the l i terature to particular species, a s  by Lowe (1924). Two collectors ap- 
pear  to have been involved, namely F. R. Mortimer and a gentleman named 
Thibault. The bulk of the collection must now be in the American Museum of 
Natural History, to whom in 1932 Lord Rothschild sold the majority of the 
birds in the Tring Museum. But a few specimens formed part  of a Roths- 
child Bequest to the British Museum in 1939. Two other smal l  collections in 
the British Museum from Aldabra include one of 26 specimens presented a s  
a Howard Saunders Bequest, collected in October and November 1906, the col- 
lector 's name unrecorded, and one of 12 specimens collected and presented 
by R. Dupont, of the Botanic Station, Seychelles, and also dated October 1906. 
1 Voelrzkow (1897, 42-43) says he arr ived on Aldabra on 21 April 1895, and (1897, 55)that 
he stayed ?or over one month, bur this cannot be reconciled with his specimen labels -Editor. 
Dupont (1907) has given an account of his visit to the archipelago, which was 
primarily an agricultural reco~naissance,  and which lasted from September 
1906 to January 1907. Two paragraphs (Dupont 1907, 23) a r e  devoted to birds, 
and appended is a bare list of species for various islands in the western 
Indian Ocean, Astove, Cosmoledo, Assumption and Aldabra al l  being shown 
separately. It is not stated what is the basis for this list, and it is not re- 
fer red  to in Section 3 below except in the case of those records which a r e  
unavailable in any other source of information. 
I have no knowledge of any further ornithological activity until 1937, when 
L. D. E. F. Vesey-FitzGerald visited the Aldabra archipelago. Few speci- 
mens were collected, but f o r  accounts of the land and sea  birds respectively, 
see  Vesey-FitzGerald (1940. 1941). Vesey-FitzGerald also obtained speci- 
mens of the sunbird ~ e c t a r i n i a  sovimanga buchenorum from Cosmoledo in 
A ~ r i l  1952 (Williams 1953a). 
. ~ 
In May 1954 the French ship Calypso visited Aldabra. Thirty-one birds 
were collected by G. Cherbonnier, between 10 and 26 May. The collection is 
now in the Mus6um National dtHistoire Naturelle, Paris, and Dr G. Roux has 
kindly provided a llst of the species and numbers of specimens of each. Dur- 
ing 1959-64 there were several visits to Aldabra by British warships, and 
accounts have been published of the observations made. The first  was by 
H.M.S. Leopard, in November 1959, for  a brief account of which see  Boulton 
(1960). In January 1962 a party from H.M.S. Owen spent three days ashore on 
Aldabra, the ship returning for twelve hours a t  the end of the next month 
(Morris 1963, a s  annotated by Bourne). In March 1964 H.M.S. Owen again 
visited Aldabra (and also Cosmoledo, Astove and Assumption). The observa- 
tions made by the ship's personnel were written up by Bourne (1966). 
The Bristol Seychelles Expedition 1964-65 spent part of November and 
December 1964 on Aldabra, a s  a result  of which there a r e  already several  
publications. There is a general account of the birds by Penny (19651, the 
expedition's leader. Dawson (1966at has reported on the sea birds of the 
Seychelles generally, including also the Aldabra archipelago, while Gaymer 
(1966) has presented a case for the conservation of Aldabra. They caught, 
measured, weighed and released many land birds, the results of which 
Gaymer has been kind enough to place at my disposal. They also collected 
19 specimens, which he has allowed me  to use in the writing of this paper, 
and which a r e  to be presented by the Expedition to the British Museum. 
2. ACKNOWLEDGMENTS 
Dr D. R. Stoddart, of the Department of Geography, Cambridge Univer- 
sity, who invited me to write this paper, has readily responded to various 
requests for assistance. Dr W. R. P. Bourne has made available papers f rom 
Sea Swallow, examined various specimens with me in the British Museum, 
and criticised part of the original draft  of this paper. A s  already mentioned, 
R. Gaymer has placed certain information and specimens which he collected 
a t  my disposal. I a m  most grateful for  his generosity in these matters. I 
must also thank D. Goodwin for examining with me in the British Museum 
material of the turtledove Streptopelia picturata, 
The specimens studied at f irst  hand a r e  mostly in the British Museum 
(Natural History), London, where J. D. Macdonald and his staff have provided 
every possible facility. I have also been fortunate to have had available at my 
place of employment, in the Department of Zoology, Cambridge University, a 
collection of over 1,000 specimens from the Malagasy Region (for a definition 
of which, see  Section 3). It was assembled by Professor A. Newton, in charge 
of the Department from 1866 until his death in 1907, and his brother Sir 
Edward Newton, resident on Mauritius from 1859 to 1877. It includes a few 
of Abbott's Aldabra specimens, obtained in 1894 by exchange with the Smith- 
sonian Institution. 
In May 1966 I spent a week in the Musgum National dfHistoire Naturelle, 
Paris, in pursuance of a long-term study of the origins of the land avifauna 
of the Malagasy Region, and received all possible help f rom Drs J. Dorst, 
C. Jouanin and F. Roux. A t  this time I had no special interest in Aldabra, 
though I did take some note of a few of the specimens collected by Cherbon- 
nier. A s  already recorded, Roux has now provided a complete list of them, 
and has moreover lent me several  of particular interest. 
Special thanks a r e  due to Dr George E. Watson, of the Smithsonian Institu- 
tion, who lent me a t  short notice by a i r  mail a number of Abbott's specimens, 
including the complete skin of a flamingo. He has also quickly responded to 
inquiries about some other specimens. I am also most grateful to Dr J. Stein- 
bacher for lending me some of Voeltzkow's specimens and for information 
about others. 
Finally, I thank R. E. Moreau, W. R. P. Bourne, R. Gaymer and D. R. 
Stoddart for their comments on this paper. 
3. SYSTEMATIC LIST 
This list is divided into (1) land birds and (2) sea birds. The lat ter  head- 
ing includes consideration of species occurring (or likely to occur) on Aldabra 
included in Alexander (1955). The land bird list is subdivided into (a) species 
which breed on Aldabra and may be presumed resident; (b) migrants, (i) al- 
ready recorded, and (ii) not yet recorded but likely to occur; and (c) species 
whose status is still  uncertain. 
The term Malagasy Region is employed in the same sense a s  by Moreau 
(1964), and includes Madagascar, the Mascarene Islands (Rbunion, Mauritius 
and Rodriguez), and other oceanic islands in the western Indian Ocean to a s  
f a r  north as  the Seychelles. The term Aldabra archipelago includes Aldabra, 
Assumption, Cosmoledo and Astove, though not Gloriosa. 
In general, the nomenclature, both scientific and English, follows that of 
Watson, Zusi and Storer (1963). Subspecific names a r e  not used except where 
they seem to have been reasonably satisfactorily established. English names 
a r e  the equivalent of scientific specific, rather than subspecific, names. 
A sign "0" indicates an unsexed specimen. The average of measurements 
is often given in brackets following the extremes. 
It should be well-known that Bergmann's Rule is to the effect that in warm- 
blooded vertebrates the smaller-sized geographic forms of a species a r e  
found in the warmer parts of the range, the larger-sized in the cooler parts 
of the range. 
(1) Land Birds 
(a) B~eeding Residents (ov p~esumed so) 
Dawson (1966a, 7) records the Indian Reef Heron Demiegretta asha a s  
breeding exclusively on Astove. But if this is so, i t  could also do s o  on Alda- 
bra. However, in the absence of supporting details one cannot be convinced 
that it breeds even on Astove, especially as  according to Watson, Zusi and 
Storer (1963, 24) it is not known to breed otherwise nearer to Astove than 
Ceylon. It may also be mentioned here that Vesey-FitzGerald (1940, 488) 
found the Madagascar Grass-Warbler Cisticola cherina abundant on Cos- 
moledo and Astove, though he did not see  it on Aldabra. Unfortunately the 
specimen which he collected and sent to the British Museum cannot be traced. 
Ardea cinerea cinerea Linnaeus Grey Heron 
---
According to Abbott (in Ridgway 1895, 530,  this species breeds on Alda- 
bra, and nests with young were seen in November. One specimen was col- 
lected, and likewise by Voeltzkow (Berlepsch 1899, 495). Nicoll (1906, 695) 
records it from both Aldabra and Assumption. Morris (1963) saw a few on 
Aldabra, but Bourne (1966) records "hundreds". Dupont (1907) l is ts  i t  from 
throughout the archipelago. 
Benson (1960a, 31) considers that two specimens from the Comoros a r e  
better placed with A. c. cinerea than _A. c. f irasa Hartert of Madagascar, the 
lat ter  distinguishable by longer measurements for  the culmen and tarsus 
(respectively 131 - 145 as  against 110 - 133, and 185 - 200 a s  against 155 - 
182 mm.). He thought that four immature specimens from Aldabra and A s -  
sumption were also best placed with A. c. cinerea, though possibly not fully 
grown. Berlepsch (1899, 495) gives the wing of Voeltzkow's specimen a s  465, 
culmen 140, tarsus 165 mm. The tarsus  measurement is well within the 
range of A. c. cinerea. That for  the culmen agrees better with A. c firasa, 
--  -
hut may have been taken from the base of the skull instead of the end of the 
frontal feathering a s  in Benson's measurements. A specimen in Cambridge 
f rom the Amirante Islands, collected in December 1864, has wing 424, cul- 
men (from frontal feathering) 120, tarsus  170 mm., thus agreeing with A. 5. 
c a a .  It is concluded that the populations frequenting all of the above- 
mentioned islands a r e  best attributed to this subspecies, and a r e  accord- 
ingly of African rather than Madagascan origin. 
Butorides striatus crawfordi Nicoll Little Green Heron 
B. -- s. crawfordi, of which I have seen the type, an adult male in the Britisb 
Museum from Assumption, and another adult male therein from Aldabra, can 
easily be distinguished from - B. - s. rhizophorae Salomonsen, of the Comoros, 
by the paler grey of the underside. I have also been lent the specimen col- 
lected by Abbott On Aldabra (Ridgway 1895, 531). It is a male in immature 
dress, and cannot be used in considering subspecific differences based on 
colour. The same applies to a female in Paris  collected on Aldabra by Cher- 
bonnier, which I have also seen. But al l  four specimens a r e  smaller than 
rhizophorae, see  below. Presumably there is the same sexual colour dif- 
ference in the adult of crawfordi a s  in rhizophorae and B. s javanicus 
(Horsfield). that is, the female has the sides of the neckTciest and abdomen 
washed with brown; and the spotting on the throat more strongly pronounced 
(Benson 1960a, 34). 
Benson (1960a) gives the wing-length of 16 specimens of rhizophorae a s  
170 - 180 mm. Thirteen specimens in  London, Paris  and Cambridge from 
Reunion, Mauritius and Rodriguez, doubtfully separable from the Asiatic 
javanicus, measure 167 - 181 mm. On the other hand, 10 specimens from the 
Seychelles (MahG, Cousin, Praslin, La Digue), attributable to B. - -  s. degens -
Hartert, measure 159 - 168 mm. only. Like degens, crawfordi is also small, 
a s  the following figures show: 
Adult 8" 159, 161 mm. 
Immature 6 159 mm. 
Immature ? 157 mm. 
An immature male collected by Voeltzkow which I have been lent has wing 
152 mm., and may not be quite fully grown. This certainly applies to an im- 
mature specimen in Cambridge from the Amirantes, with wing 140 mm. only. 
Benson (1960a, 34) accepts the contention of White (1951, 460) that rhi- 
zophorae is of Asiatic origin, and there is no reason to suppose that this does 
not also apply to crawfordi. On the other hand, - B. - s. rutenbergi (Hartlaub) of 
Madagascar is very close to - B. - s. atricapillus (Afzelius) of Africa, whence 
White suggests that degens of the Seychelles is also derived. 
Abbott (in ~id~wa-5, 531) found this species quite common on Alda- 
bra, breeding among mangroves in November and December, laying two 
eggs. Probably the breeding season is fairly extensive, since in the Comoros 
Benson (1960a, 35) obtained data pointing to egg-laying in August and Septem- 
ber. Abbott also noted that the birds stand for hours on the backs of turtles, 
catching the blue-bottle flies which swarm on the turtles' backs and heads. 
Dupont (1907) lists this species from throughout the archipelago. 
Egretta garzetta dimorpha Hartert Little Egret 
E. dimorpha has often been regarded a s  a full species, a s  by Watson, 
~ u s i a n d  Storer (1963). However, I see  no reason to differ from the opinion 
of Grant and Mackworth-Praed (1933) and Berlioz (1949, 20), for example, 
that dimorpha is conspecific with E. garzetta. Dimorpha inhabits Madagas- 
c a r  and the Aldabra archipelago, and is notable for the common occurrence 
of a dark blue-grey phase a s  well a s  a white phase. A grey phase also occurs 
in coastal eastern and north-eastern Africa and in coastal West Africa 
(White 1965, 25), but is r a r e  o r  quite absent in the interior of Africa. Grant 
and Mackworth-Praed (1933) have separated the populations of Aldabra and 
Assumption as  E. g. assumptionis, differing from dimorpha by i ts  longer bill. 
- - 
This was on the basis of material in the British Museum. There is no further 
material available therein. While due note must be taken of this difference, 
the measurements presented show an appreciable overlap. On existing evi- 
dence it is difficult to justify recognition of assumptionis. 
Abbott (in Ridgway 1895, 530, under Demigretta gularis) found this the 
commonest heron on Aldabra, and breeding in large numbers in December, 
laying f rom two to four eggs. The white phase was twice o r  thrice as num- 
erous a s  the blue. Nicoll (1906, 696, 704, under Demiegretta s ac ra )  collected 
i t  on both Assumption and Aldabra, finding i t  extremely abundant on the 
latter. A specimen collected on Aldahra was partially white and dark. I can 
confirm that this applies to both this and another specimen from Aldabra, 
both in the British Museum. Morr is  (1963) found both phases plentiful on 
Aldahra. Bourne (1966) records hundreds, of which about forty per  cent 
were in the dark phase. He also records  i t  from Cosmoledo, where the 
phases were about equal, while one "White-faced Heron" was seen on Astove 
(presumably this was a specimen of - E. - g. dimorpha in the dark phase, in 
which the chin and throat a r e  s t i l l  white). He gives no record f rom Assump- 
tion, and possibly i t  has been extirpated there. Dawson (1966a, 7) records 
la rge  flocks on Cosmoledo, Astove and Aldabra, the proportion of light to 
dark birds being about seven to three, with the occasional intermediate pie- 
bald. 
Milon (1959) found that in two breeding colonies in Madagascar selected 
for  study the ratio of the dark phase to the white phase was about 35: 65. The 
observations from the Aldahra archipelago tend roughly to bear  this out. 
Threskiornis aethiopica abbotti (Ridgway) Sacred Ibis 
This species occurs in Africa (T. -- a. aethiopica (Latham)), Madagascar 
(T. -- a. bernieri (Bonaparte)) and Aldabra (T. a. abbotti). The characters  on 
- -  -
which these three subspecies can be recognised may be summarised as 
follows (it should he re  be mentioned that immature specimens of all  three 
have the head and neck feathered, whereas in adults these a r e a s  are bare): 
Feathering on head and neck (in immature): In aethiopica and bernieri 
white heavily streaked hlack; in abbotti hlack streaking much reduced, and 
only on a few feathers. (Only one immature  specimen of abbotti was avail- 
able. But the difference was striking, and shows up well in three  photo- 
graphs in Nicoll (1908).) 
Decomposed tertials: Glossy purplish slate in aethiopica, bluish s la te  
in bernieri,  much paler than in aethiopica; bluish slate  in W i ,  a s  in 
bernieri, but darker. 
Metallic green tips to remiges: Extending back 40 - 60 mm. in aethiopica; 
not more  than 15 mm. in bernieri, in three  out of eight specimens absent; not 
more than 10 mm. in abbotti, in four out of s ix  specimens absent. 
I r i s  (in adult): Brown in aethiopica (see for  example McLachlan and 
Liversidge 1957); white in bernieri; bluish-white in -. (The difference 
between bernieri and - abbotti is a s  given by Ridgway 1895, 530, and is con- 
firmed from the labels of one adult specimen of the former and two such of 
the latter. An immature specimen of abbotti had the iris very dark brown.) 
Ridgway also suggests that the lower half of the neck i s  entirely naked in 
abbotti, but not s o  in bernieri. I cannot convince myself that the extent of 
-
feathering up the neck is not variable in the adult of al l  three subspecies, and 
that i t  can he used a s  a distinguishing character. Ridgway further suggests 
that the tips to the remiges differ in colour, but i t  seems that there is only a 
difference in i t s  extent. 
Presumably bernieri was derived from aethiopica, and probably 
from bernieri rather than aetbiopica. The colour of the decomposed tertials, 
the reduction of the dark tips to the remiges, and the colour of the iris all  
suggest a closer relationship of abbottito bernieri than to aethiopica. 
The following a r e  measurements in mm. of the material of bernieri and 
abbotti studied, in London, together with two specimens of bernieri in 
-
Cambridge: 
Culmen from 
Wing base Tarsus 
Bernieri 
Adult 6 374 169 95 
Adult ? 9 342 348 362 132 137 144 72 76 82 
Immature 6 357 182 84 
Immature q p 334 340 136 143 74 78 
Immature 0 371 broken 87 
Abbotti 
Adult 9 ? 336 340 125 132 76 76 
Adult 0 335 337 338 125 133 136 70 70 72 
Immature 6 347 176 80 
These figures do not suggest any marked difference between the two sub- 
species. Evidently males a r e  longer billed in both. 
Falco newtoni aldabranus Grote Madagascar Kestrel 
-
It is presumed that Madagascar, inhabited by - F. - n. newtoni (Gurney), has 
been the source of origin for  the populations elsewhere in the Malagasy Re- 
gion, namely F. punctatus Temminck of Mauritius, F. & aldabranus of Alda- 
bra, and F. a z e a  (Oberholser) of the Seychelles. A single unsexed specimen 
of aldabranus (judging from its  wing-length) from Anjouan, in the Comoros, 
is considered by Benson (1960a, 39) to have been a stray from Aldabra, but is 
discussed further below. Failure to colonise the Comoros may be because the 
islands a s  a whole were probably originally almost wholly covered with ever- 
green forest (Moreau 1966, 346). In Madagascar, Rand (1936, 378) found the 
species everywhere except in heavy forest. 
Benson (1960a, 39) studied to some extent the material in London. It has 
been re-examined, 13 specimens in Cambridge have also been considered, 
and wing-lengths taken of three specimens of aldabranus collected by Cher- 
bonnier, in Paris. Material of - -  F. araea in London, Par is  and Cambridge has 
also been considered. 
From field observations, Gaymer tells me that the male of F. n. alda- 
branus is more brightly coloured than the female. I cannot make any personal 
judgment in this matter, since the only two specimens examined after I had 
preceding the mining of guano, during which the natural vegetation was de- 
stroyed on several islands and certain birds and other animals became ex- 
tinct. In more recent years, we have the observations made by Vesey-Fitz- 
Gerald on the vegetation and the birds in 1937, and the largely geological 
observations of Baker and Piggott in 1960-61. The Bristol Seychelles Expe- 
dition spent some hours ashore on Cosmoledo Atoll (Menai Island) on 9 
November 1964 and on Assumption on 10 November 1964. The following year 
R. Gaymer, of that expedition, made a short  visit to Cosmoledo on 1 October 
1965 and to Assumption on 3 October 1965. I am grateful to R. Gaymer for 
sending me a copy of his observations on these islands. 
Because the information on these islands is s o  scattered, the salient fea- 
tures of the ecology of each of the seven islands o r  atolls listed a r e  here  sum- 
marized, with reference particularly to the vegetation, the reptiles, and the 
birds. In preparing this summary, l is ts  were compiled of the plants collected 
o r  recorded from each island, based on published accounts, particularly those 
of Dupont (1907) and Hemsley (1919), and use was made of the l is ts  of birds 
by Watson, Zusi and Storer (1963). For  the information on insects I have re-  
lied on the summary by Scott (1936) and no special search has been made of 
the papers in the Percy Sladen Expedition Reports. The most important gen- 
e ra l  sources a r e  Coppinger (1883), Dupont (1907), Fryer (1911), Vesey- 
FitzGerald (1940, 1941, 1943, Watson, Zusi and Storer (1963), and Baker 
(1963). The summary account of each island does not contain citations for 
each statement, but a list of the more important references, less  important 
references, and maps is appended to each: full citations a r e  given in the 
"Bibliography of Aldabra" in this Bulletin. 
This summary does not treat the Amirantes and Desroches, Cargados 
Carajos, Agalega, o r  Tromelin. 
1. ASSUMPTION g046's., 46031fE. 
Assumption is an elevated reef island 20 miles south of Aldabra, 3.75 
miles long and 0.3-1.0 miles wide. The deeply dissected reef rock r i ses  to 
20 ft  above sea level, with dunes on the east and south sides rising to 90 
feet. Early in the century the island was wooded in the west and southwest, 
and the centre was only thinly vegetated. The vegetation resembled that of 
Aldabra, and 68 species of flowering plants have been recorded, three of 
them endemic (Panicum assumptionis, Eriochlea subulifera, Stenotapb- 
clavigerum). The dunes a r e  covered with Sporobolus and clumps of Sclero- 
-
dactylon, with patches of -a, Scaevola and Tournefortia. The centre of 
the island had a few Hibiscus bushes, and coconuts a r e  planted on sand along 
the west shore. The res t  of the island has been stripped of vegetation during 
guano-digging, and there a r e  now only a few stunted bushes in holes and pits, 
the ground being covered with Plumbago aphylla. Some Casuarina have been 
planted on the west coast. No mangroves a r e  recorded. 
Tortoises formerly existed here, and Fryer found their remains. There 
is a skink Ablepharus boutonii, and two geckos, Phelsuma abbotti -- abbotti and 
Hemidactylus mercatorius. 65 species of insects a r e  recorded. -- Birgus latro 
was common in 1906. Marine turtles formerly nested here in large numbers, 
but only a few a r e  reported to do so now. 
Large numbers of boobies and terns formerly bred on the island, but have 
disappeared as  a result of mining operations. Abbott's Booby, Sula abbotri. is 
now extinct on Assumption and is found only on Christmas Island. Vesey- 
FitzGerald gives the date of i t s  disappearance as 1926. Sea and shore birds 
recorded as  breeding on Assumption a r e  Sula abbotti (extinct), Butorides 
striatus, Ardea cinerea, Egretta garzetta dimorpha, (which may also be ex- 
---
tinct), and possibly Sula sula. Others recorded from the island a r e  =a 
dactylatra melanops, Sterna sumatrana mathewsi, Gygis alba monte, PhAethon 
rubricauda ruhricauda, and Dromas ardeola. Resident land birds recorded 
a r e  Streptopelia picturata coppingeri, Nectarinia sovimanga abbotti, Centro- 
pus toulou assumptionis, and Dryolimnas cuvieri abbotti. The rail, collected 
-- --
by Abbott in 1892 and described by Ridgway in 1893 and 1894a, became ex- 
tinct between 1906 and 1937. The coucal and turtledove may also have disap- 
peared. Gaymer recorded Corvus albus in 1965. 
Guano reserves a r e  the largest in the western Indian Ocean: 161,000 
tons were exported during 1926-1945, and Baker estimates the remaining re- 
serves at 160,000 tons. Mining ceased in 1945, but has started again since 
1955; a mechanical crusher and light railway have been installed. Goats were 
introduced in early 1887 by a whaler, became feral, and were later  used to 
colonise Aldabra; Abbott states that they were brought from Europa Island in  
the Mozambique Channel. Nicoll found twenty in 1906, but according to Gaymer 
they no longer exist. Nicoll also found numerous ra t s  which were threatening 
to eliminate some of the r a r e r  birds. 
Main references: Abbott 1893, 763; Baker 1963, 101-106, 124-126; Dupont 
1907, 12-13; Fryer 1911, 431-433; Nicoll 1906; Nicoll 1908, 107-113; Ridgway 
1895, 520-523; Vesey-FitzGerald 1940; Vesey-FitzGerald 1941; Vesey-Fitz- 
Gerald 1942, 12-13; Watson, Zusi and Storer 1963. 
Additional references: Honegger 1966b; Ridgway 1893; Ridgway 1894b; 
Vesey-FitzGerald and Parker 1947. 
Map: Baker 1963, 102. 
2. ASTOVE 10?06'S., 47'45'E. 
Astove is an elevated coral  atoll 3.5 miles long and 2.5 miles wide, con- 
sisting of a reefrock rim 15 feet high, with sand dunes 45-50 feet high on the 
east coast. According to Baker reefrock covers 583 and sand 642 acres. The 
lagoon averages 3-4 feet in depth, with a maximum of 10 feet, and the en- 
trance dries at low water. The fringing reef is 200 yards wide. 
The dunes a r e  covered with Suriana on the windward side, and with 
Scaevola and Tournefortia to leeward. Lagoonward of the dunes, champignon 
is covered with Pemphis thicket. The lagoon is filled with fine sediment, and 
is ringed with scattered Avicennia trees,  but otherwise there is no man- 
grove. On the western lagoon shore, beach ridges a r e  colonised by Sporobo- 
u, and planted with coconuts and Casuarina. Pemphis grows on bare reef- 
rock, and Scaevola and Tournefortia on sand. The sea  coast on the leeward 
side has a thicket of =a, Scaevola and Tournefortia. A deciduous scrub 
covers the surface on the wider parts Of the eastern side, with frequent 
Pisonia trees. 59 species of plants a r e  recorded from Astove. 
Tortoises formerly occurred here, according to Rothschild, and Fryer re- 
ports the finding of possible remains. Other reptiles include Phelsuma astriata 
astovei, Hemidactylus mercatorius, and possibly Ablepharus boutonii. Fryer  
also found that insects were numerous (27 species a r e  recorded) and butter- 
flies especially common. The land birds include Nectarinia sp., Zosterops 
maderaspatana, and a flightless rail, Dryolimnas c-. Abbott reported 
the rai l  from hearsay, but it was probably extinct by 1906. Large numbers of 
Egretta garzetta have recently been recorded, together with Ardea cinerea 
and Butorides striatus. There a r e  records of Buhulcus ibis ibis, Thalasseus 
bergii thalassina and possibly Demiegretta asha. Sula sula may be the only 
--- 
breeding sea  bird; Corvus alhus and Cisticola cherina have appeared; and 
--
there is a record of Hydroprogne caspia. 
Guano is found on the west side, and has been mined since 1927. 70,000 
tons have been reported, and 5000 tons are  left, according to Baker. Most of 
the native vegetation in the guano area  has disappeared, though some Pisonia 
grandis and occasional Sideroxylon inerme remain. It has been replaced by 
-- 
Plumbago aphylla, with Dactyloctenium pilosum and Stachytarpheta indica; 
Agave and Gossypium a r e  also found. Coconuts a r e  grown on the west side, 
-
though not very successfully, and maize has been grown in the dunes. 
Main references: Baker 1963, 92-97; Dupont 1907, 2-8; Fryer  1911, 426- 
428; Piggott 1961, 6-8; Vesey-FitzGerald 1942, 10-12; Watson, Zusi and 
Storer 1963. 
Additional references: Honegger 1966b; Vesey-FitzGerald 1940; Vesey- 
FitzGerald 1941. 
Map: Piggott 1961; Baker 1963, 94. 
3. GLORIOSA 11?34's., 45'13'E. 
The Gloriosa Islands a r e  situated 114 miles west-north-west of Mada- 
gascar, and consist of two sandy islands with a grass-covered rock between 
them. Gloriosa, the larger island, is 1.5 miles long, and has dunes 50-60 
feet high on i ts  lee side, and a central tidal marsh which dries at low water. 
Ile du Lise, three miles away, is smaller, but has a dune 30 feet high, and 
also beachrock and conglomerate. Coppinger found a block of basalt on the 
reef, together with quartz pebbles. 
Little is known of the biota. Gloriosa has been planted with coconuts and 
the "dense growth of virgin forest" seen by Coppinger in 1882 has since been 
cleared. Ile du Lise still has woodland on it, with Ficus, Hibiscus and Scae- 
v*, and Pemphis in the central swamp. Maize used to be grown in large 
amounts on Gloriosa. Coppinger collected on the islands in 1882, and they 
were also visited by Abbott and Nicoll. According to Hemsley, Abbott found 
mangroves 50-60 feet high, but Abbott's actual record was of sand dunes. 30 
species of plants have been recorded. 
According to Rothschild, tortoises formerly existed on Gloriosa, but no 
supporting evidence for this can be found. Abbott records three small rep- 
tiles: Hemidactylus mabouia, Ablepharus gloriosus, and Zonosaurus mada- 
gascariensis. Nicoll found numerous hutterflies and moths, and (on du Lise) 
Coppingt,r found many spiders and hermit crabs. Both Coppinger and Nicoll 
report Birgus latro on du Lise but not on Gloriosa. Green and hawksbill 
--
turtles used to nest on Gloriosa and may still  do so. The known resident land 
birds a r e  Streptopelia picturata coppingeri, Hypsipetes madagascariensis 
e i ,  Nectarinia sovimanga sovimanga, and Zosterops maderaspatana 
maderaspatana; together with Corvus albus, which is common. Nesting sea- 
--
birds include Sula sula, Fregata sp., Sterna fuscata, and Anous stolidus 
-- -
pileatus: large numbers of the noddies were nesting in 1906 on the rock 
between the islands. Sula abbotti may also have bredin  the past. Phaethon 
-- 
rubricauda rubricauda may also breed, and other species recorded a r e  
Dromas ardeola, Sterna sumatrana mathewsi, Thalasseus bergii thalas- 
--
sina, and Thalasseus bengalensis, Two vagrants and one migrant a r e  also 
-
recorded. The domestic fowl, Gallus gallus, has become feral. Feral  cats 
--
were common in 1893, and were reducing the numbers of birds. In 1882 
there were abundant brown ra ts  on both islands. 
Main references: Abbott 1893, 763-764; Coppinger 1883, 237-240; Cop- 
pinger 1884; Nicoll 1906, 686-692; Nicoll 1908, 100-106; Watson, Zusi and 
Storer 1963. 
Additional references: Holland 1896; Ridgway 1895, 524-526. 
Map: Guilcher and others 1965, 14, fig. 4. 
4. COSMOLEDO g041'S., 47'35'E. 
Cosmoledo is an atoll 9 miles long and 7 miles wide, with a lagoon 5 
miles in diameter with maximum depth of 4-1/4 fathoms. There a r e  five 
main islands and several smaller  ones on the atoll rim, which has an aver- 
age width of one mile. Menai Island has the largest area, but Wizard Island 
o r  Grande Ile, 2 miles long, is the longest. The islands a r e  formed of up- 
lifted reefrock, much eroded, reaching 12-15 feet above sea-level, with 
large amounts of sand banked against the rocky remnants. 
At Menai Island on the west r im the seaward coast (leeward) has a dune 
scrub with Guettarda; dunes r i se  to 40 feet a t  the north end. The lagoon 
coast has mangroves 80 feet tall, with a succession of Avicennia-Bruguiera- 
Rhizophora from sea to land. Dunes a r e  also found inside the mangrove. 
Pemphis scrub covers champignon in the centre of the island. The eastern 
islands, Polyte and Wizard, have a seaward dune fringe up to 55 feet high, 
covered with Sporobolus and Suriana on the seaward side, and with Tourne- 
fortia to leeward. Pemphis again covers the reefrock. The smaller  islands 
-
a r e  rocky, with Pemphis, Sideroxylon and Plumbago. The known flora totals 
56 species. 
Tortoises formerly existed at Cosmoledo, and Fryer  reported finding 
their fossil eggs. Other reptiles include Phelsuma abbotti menaiensis, 
Hemidactylus mercatorius, and Ablepharus boutonii. 37 species of insects 
a r e  recorded, and three species of land mollusca. There a r e  three recorded 
resident land birds: Zosterops maderaspatanc maderaspatana, Nectarinia 
sovimanga buchenorum, and Dryolimnas cuvieri. Abbott reported the ex- 
istence of the rai l  from hearsay, and according to Fryer  i t  existed in 1919 on 
South Island, though he did not land there and observe it. The breeding sea 
birds a r e  Phzethon rubricauda rubricauda, S& dactylatra melanops, 
sula, Fregata minor, Sterna anaethetus, Sterna fuscata, and Anous stolidus 
- -- --
pileatus. Large flocks of Egretta garzetta and small number of Dromas 
ardeola have recently been recorded. Corvus alhus is known and Cisticola 
-
cherina has been introduced. Both Ardea cinerea and Butorides striatus 
probably breed. 
Guano deposits a r e  found on North Island, and have been worked; there 
a r e  reserves of 3,500 tons. 
Maize and coconuts a r e  grown. Dupont recorded rabbits in 1906. Apart 
f rom notes on sea birds there is no recent information on the biota of 
Cosmoledo, though the ra i l  is thought to be extinct. 
Main references: Baker 1963, 86-92; Dupont 1907, 8-12, Fryer  1911, 
428-430; Vesey-FitzGerald 1942, 13-15; Watson, Zusi and Storer 1963. 
Additional references: Connolly 1925; Ridgway 1895; Vesey-FitzGerald 
1940; Vesey-FitzGerald 1941. 
Maps: Admiralty Chart 718 (survey of 1878); individual islands mapped 
by Baker 1963, 87, 89, 91, 93. 
5. FARQUHAR (JOAO DE NOVA) 1 0 ~ 1 0 ' ~ . ,  5 1 ~ 7 ' ~ .  
Farquhar is an atoll 11.5 miles long and 6.5 miles wide, maximum 
dimensions, with two main islands (South Island, North Island) on the 
eastern rim, the small  island of Goelette on the southeast side, and three 
smal l  islets on the north. The lagoon is shallow and full of patches, except 
near the east  r im, where there is a deeper basin with up to 6 fathoms and 
an entrance on the north side with 3-5 fathoms. Fryer  reports some residual 
elevated reefrock, but according to Baker the islands a r e  all sand cays and 
there is no elevated rock. Most of North Island is less than 10 feet above 
sea  level, with dunes 5-50 feet high a t  the south end; South Island has dunes 
50-70 feet high. Goelette is low and sandy. 
Very little is known of the biota. Pemphis, Tournefortia, Scaevola, 
Casuarina and coconuts a r e  the only plants recorded. According to Roths- 
child the giant tortoise formerly occurred here, but no supporting evidence 
is known fo r  this. 63 species of insects a r e  known. Among the sea birds Sula 
dactylatra melanops, Sterna sumatrana mathewsi, and Sterna fuscata breed on 
Goelette, and Sula sula rubripes on South Island. e s  tenuirostis 2
m s  is recorded roosting but not breeding. There i s  a single native land 
bird, Foudia madagascariensis, which is common. Gardiner states that the 
Barred Ground Dove Geopelia str iata has been introduced and is common a t  
the settlement on North Island (Grande Poste). 
There a r e  no commercial guano deposits, except for some phosphatic 
sandstone and guano on the two main islands, but according to Piggott mining 
has disturbed the breeding colonies of terns. There a r e  settlements on both 
North and South Islands, and a jetty on the former. 
Main references: Baker 1963, 80-85; Gardiner 1907, 142-145; Gardiner 
1936, 432-433. 
Additional references: Carpenter 1916; Cockerel1 1912; Edmondson 1923; 
Fleutiaux 1923; Fore1 1907; Fryer  1910; Fryer  1912; Gardiner 1906; Grou- 
velle 1913; Hampson 1920; Jordan 1939; Maulik 1931; Needham 1913; Scott 
1912; Vesey-FitzGerald 1940; Vesey-FitzGerald 1950. 
Maps: Admiralty Chart 718 (survey of 1878); Baker 1963, 81. 
6. ST PIERRE g019'S., 50'43'~. 
St Pierre  is a circular uplifted atoll 0.75 miles in  diameter, with an area  
of 417 acres,  situated 270 miles east of Aldabra and 19 miles southwest of 
Providence. The coastal cliffs rise to 8-30 feet above sea-level, with no 
fringing reef, and the reefrock is deeply intersected by caves and crevices. 
Dunes 10 feet high a r e  perched on the cliffs near blowholes. The centre of 
the island is close to sea-level, and has a small tidal pool. Physiographically 
the island resembles Assumption. 
The native vegetation consisted of Sporobolus on the dunes; Suriana and 
Tournefortia, o r  Pemphis, along the lee coast; and a scrub of Pemphis, 
Hibiscus,=a and Euphorbia over the rest  of the island. Coppinger men- 
tioned a dense growth of scrubby bushes and three o r  four palms in 1882. 
25 species of land plants a r e  recorded, and the flora was clearly like that 
of Aldahra and Assumption. Maize and tobacco have been grown. 
The fauna formerly included the giant land tortoise, according to Roths- 
child, hut no direct evidence of this has been found. Apart from the Mada- 
gascar fody, -a madagascariensis, there a r e  no land birds, and though 
Sula sula ruhripes formerly nested in large numbers, i t  does not do so now. 
--
The ecology of the island has been drastically altered by the mining of 
guano and high grade phosphate rock, which began in 1906. Between 1926 and 
1960, 151,000 tons were exported, and reserves of 10,000-15,000 tons re- 
main. The island surface is now a "maze of pits and crevices a s  a result of 
guano working", according to Baker. The mining has resulted in almost total 
destruction of the vegetation. "On the east coast a few scattered specimens 
of Pemphis bushes still exist whilst only two extremely battered specimens 
of have been left on the centre of the island. Of the herbs which sur- 
vive on the remains of the soil, Stachytarpheta e is the most common" 
(I'iggott 1961). Piggott also records the introduction of Gaillardia pulchella; 
together with the following exotics near the settlement: -a stramonium, 
Asystasia gangetica, Agave sp., Carica papaya, and Muss sp. Casuarina 
has been planted a s  a windbreak, and is doing well. The guano has continued 
to be worked, and a crushing plant has been installed. 
Main references: Baker 1963, 100; Coppinger 1883, 236; Dupont 1907, 
1-2; Gardiner 1907, 148-149; Gardiner 1936, 434-435; Piggott 1961; Vesey- 
FitzGerald 1941; Vesey-FitzGerald 1942, 15; Watson, Zusi and Storer 1963. 
Map: Baker 1963, 100. 
7 .  PROVIDENCE g014's., 5 1 ? 0 2 ' ~ .  
Providence Island is situated a t  the north end of the 25 mile long, 6 mile 
wide Providence Bank. It is 2.75 miles long and 1200 yards wide, with a reef 
platform on the west side. The island is  sandy, without elevated reefrock, and 
is covered with coconuts and Casuarina. 33 species of plants a r e  recorded, 
mostly collected by Coppinger in 1882 and by Dupont. Coppinger also records 
the following cultivated plants: pawpaw, custard apple, pepper, sweet potato, 
onions, lettuce, and capsicum. 
Very little is known of the fauna. Rothschild records the former existence 
of the giant land tortoise, but on unknown authority. Coppinger found seven 
giant tortoise imported from Aldabra roaming in the woodland in 1882; and 
he also states that green turtle nest on the island in April. There a r e  22 re-  
corded species of insects. There a r e  no land birds. Sea birds breeding on the 
bank include Sterna bergii thalasseus, -6 -- alba monte, and possibly Dromas 
ardeola. Shore birds breeding on the bank include Sterna bergii thalasseus, 
Gygis alba monte, and possibly Dromas ardeola. Shore birds breeding in- 
--- 
elude Ardea cinerea, and Butorides striatus is recorded. There a r e  also nine 
records of vagrants and migrants. 
Guano reserves have been considerable, covering 147 acres at the north 
end of the island, out of a total area  of 388 acres. Between 1935 and 1949 
27,260 tons were exported, and Baker estimates reserves at 9,000 tons. 
Cerf Islands (Banc du Sud), at the southern end of Providence Bank, is 
now a single large sand cay, with four smaller ones, while in 1905 there 
were seven small  islands. Casuarina and Scaevola a r e  recorded, and coco- 
nuts and cassava a r e  said to be grown. Coppinger found only pioneer vege- 
tation and bushes in 1882. 
Main references: Baker 1963, 77-80; Coppinger 1883, 231-236; Gardiner 
1907, 146-148; Gardiner 1936, 434-435; Watson, Zusi and Storer 1963. 
Additional references: Butler 1884; Carpenter 1916; Coppinger 1884; 
Fryer 1911; Holland 1896; Line11 1897; Maulik 1931; Ridgway 1895; Schenkling 
1922; Scott 1913; Warburton 1912. 
Chapter 4 
THE BIRDS OF ALDABRA AND THEIR STATUS 
C. W. Benson 
Department of Zoology, Cambridge University 
1. Historical introduction 
2. Acknowledgements 
3. Systematic List  
(1) Land Birds 
(a) Breeding Residents 
(b) Migrants 
(c) Of Uncertain Status 
(2) Sea Birds 
4. The Land Birds: their status, origins, and trends 
of variation 
5. The Land Birds: composition of species 
6. Summary 
7. References 
Atoll Research Bulletin No. 118: pp. 63-111 November 15, 1967 
1. HISTORICAL INTRODUCTION 
Prior to 1892, the one and only piece of ornithological activity pertaining 
to Aldabra seems to have been the collecting by Commander Wharton, during 
the visit of H.M.S. Fawn to the atoll in July 1878, of two specimens of the rai l  
Dryolimnas cuvieri aldabranus, described by a n t h e r  (1879). They a r e  in  the 
British Museum (Natural History). It is true that Sclater (1871) had described 
a turtledove as  =r aldabranus from two specimens allegedly from Aldabra, 
but a s  will be shown their origin was almost certainly in the Amirante Islands. 
Although during the course of her voyage in 1881-82 H.M.S. Alert visited the 
Amirantes and Gloriosa, together with Providence, Cerf Islands, and St Pierre,  
she did not visit Aldabra o r  the nearby islands (Coppinger 1883; Coppinger and 
others 1884). 
Dr W. L. Abbott spent three and a half months, from September to Decem- 
ber 1892, on Aldahra, and made a thorough survey of the avifauna. His col- 
lections were sent  to the Smithsonian Institution, United States National 
Museum. The new forms collected were described by Ridgway (1893, a s  
amended 1894a; 1894b). certain nests and eggs by Bendire (18941, and finally 
Ridgway (1895) gave an account of Abbott's ornithological activities in the 
western Indian Ocean generally, quoting many field observations. 
Dr A. Voeltzkow spent from 21 May to 21 June 1895 on ~ldabra: and 
collected 59 specimens, now in the Natur-Museum und Forschungs-Institut 
Senckenberg, Frankfurt. The collection was catalogued by Berlepsch (1899). 
Voeltzkow (1917, 457-459) himself drew up a list of Aldabra birds, but it 
provided no new information. The yacht Valhalla, on which M. J. Nicoll was 
naturalist, arrived at Aldabra on 13 March 1906, and stayed there three days. 
The birds collected were reported on by Nicoll (1906), and a r e  in the British 
Museum. There is also a more general account of the visit by Nico11 (1908). 
J. C. F. Fryer  spent from August 1908 to February 1909 in the archi- 
pelago--that is, including Assumption, Cosmoledo and Astove a s  well a s  Alda- 
bra. He wrote a general account of the visit, including notes on the flora and 
fauna (Fryer  1911). These notes contain few references to birds, none of 
which were apparently collected. But Fryer (1911, 399) states that a bird 
collector for the Tring Museum spent a year there. No general account of 
this collection has been traced. There a r e  merely incidental references in  
the literature to particular species, a s  by Lowe (1924). Two collectors ap- 
pear to have been involved, namely F. R. Mortimer and a gentleman named 
Thibault. The bulk of the collection must now be in the American Museum of 
Natural History, to whom in 1932 Lord Rothschild sold the majority of the 
birds in the Tring Museum. But a few specimens formed part of a Roths- 
child Bequest to the British Museum in 1939. Two other small collections in 
the British Museum from Aldabra include one of 26 specimens presented a s  
a Howard Saunders Bequest, collected in October and November 1906, the col- 
lector's name unrecorded, and one of 12 specimens collected and presented 
by R. Dupont, of the Botanic Station, Seychelles, and also dated October 1906. 
I Voeltzkow (1897. 42-43) says  he arrived on Aldabra on 21 April 1895. and (1897. 55)that 
he stayed i o r  over one month, but this cannot be reconciled with his specimen labels-Editor.  
Dupont (1907) has given an account of his  visit to the archipelago, which was 
primarily an agricultural re~or~naissance ,  and which lasted from September 
1906 to January 1907. Two paragraphs (Dupont 1907, 23) a r e  devoted to birds, 
and appended is a hare list of species for  various islands i n  the western 
Indian Ocean, Astove, Cosmoledo, Assumption and Aldabra al l  being shown 
separately. It is not stated what is the hasis for  this list, and it is not re-  
fer red  to in Section 3 below except in the case of those records which a r e  
unavailable in any other source of information. 
I have no knowledge of any further ornithological activity until 1937, when 
L. D. E. F. Vesey-FitzGerald visited the Aldahra archipelago. Few speci- 
mens were collected, but f o r  accounts of the land and sea  birds respectively, 
see  Vesey-FitzGerald (1940, 1941). Vesey-FitzGerald also obtained speci- 
mens of the sunbird Nectarinia sovimanga buchenorum from Cosmoledo in  
April 1952 (Williams 1953a). 
In May 1954 the French ship Calypso visited Aldahra. Thirty-one birds 
were collected by G. Cherbonnier, between 10 and 26 May. The collection is 
now in the Musgum National dlHistoire Naturelle, Paris, and Dr G. Roux has 
kindly provided a l is t  of the species and numbers of specimens of each. Dur- 
ing 1959-64 there were several visits to Aldabra by British warships, and 
accounts have been published of the observations made. The first was by 
H.M.S. Leopard, in November 1959, f o r  a brief account of which see  Boulton 
(1960). In January 1962 a party from H.M.S. E n  spent three days ashore on 
Aldabra, the ship returning for  twelve hours a t  the end of the next month 
(Morris 1963, a s  annotated by Bourne). In March 1964 H.M.S. Owen again 
visited Aldabra (and also Cosmoledo, Astove and Assumption). The observa- 
tions made by the ship's personnel were written up by Bourne (1966). 
The Bristol Seychelles Expedition 1964-65 spent part of November and 
December 1964 on Aldabra, a s  a result of which there a r e  already several  
publications. There is a general account of the birds by Penny (1965), the 
expedition's leader. Dawson (1966a) has reported on the sea birds of the 
Seychelles generally, including also the Aldabra archipelago, while Gaymer 
(1966) has presented a case for the conservation of Aldabra. They caught, 
measured, weighed and released many land birds, the results of which 
Gaymer has been kind enough to place at my disposal. They also collected 
19 specimens, which he has allowed me to use in the writing of this paper, 
and which a r e  to be presented by the Expedition to the British Museum. 
2. ACKNOWLEDGMENTS 
Dr D. R. Stoddart, of the Department of Geography, Cambridge Univer- 
sity, who invited me to write this paper, has readily responded to various 
requests for  assistance. Dr W. R. P. Bourne has made available papers from 
Sea Swallow, examined various specimens with me in the British Museum, 
and criticised part of the original draft of this paper. A s  already mentioned, 
R. Gaymer has placed certain information and specimens which he collected 
a t  my disposal. I am most grateful for his generosity in these matters. I 
must also thank D. Goodwin for  examining with me in the British Museum 
material of the turtledove Streptopelia picturata. 
The specimens studied at f i rs t  hand a r e  mostly in the British Museum 
(Natural History), London, where J. D. Macdonald and his staff have provided 
every possible facility. I have also been fortunate to have had available at my 
place of employment, in the Department of Zoology, Cambridge University, a 
collection of over 1,000 specimens from the Malagasy Region (for a definition 
of which, see  Section 3). It was assembled by Professor A. Newton, in charge 
of the Department from 1866 until his death in 1907, and his brother Sir 
Edward Newton, resident on Mauritius from 1859 to 1877. It includes a few 
of Abbott's Aldabra specimens, obtained in 1894 by exchange with the Smith- 
sonian Institution. 
In May 1966 I spent a week in the MusGum National d'Histoire Naturelle, 
Paris, in pursuance of a long-term study of the origins of the land avifauna 
of the Malagasy Region, and received all possible help from Drs J. Dorst, 
C. Jouanin and F. Roux. A t  this time I had no special interest in Aldabra, 
though I did take some note of a few of the specimens collected by Cherbon- 
nier. A s  already recorded, Roux has now provided a complete list of them, 
and has moreover lent me several of particular interest. 
Special thanks a r e  due to Dr George E. Watson, of the Smithsonian Institu- 
tion, who lent me a t  short notice by a i r  mail a number of Abbott's specimens, 
including the complete skin of a flamingo. He has also quickly responded to 
inquiries about some other specimens. I am also most grateful to Dr J. Stein- 
bacher for lending me some of Voeltzkow's specimens and for information 
about others. 
Finally, I thank R. E. Moreau, W. R. P. Bourne, R. Gaymer and D. R. 
Stoddart for their comments on this paper. 
3. SYSTEMATIC LIST 
This l is t  is divided into (1) land birds and (2) sea  birds. The latter head- 
ing includes consideration of species occurring (or likely to occur) on Aldabra 
included in Alexander (1955). The land bird list is subdivided into (a) species 
which breed on Aldabra and may be presumed resident; (b) migrants, (i) al- 
ready recorded, and (ii) not yet recorded but likely to occur; and (c) species 
whose status is st i l l  uncertain. 
The term Malagasy Region is employed in the same sense a s  by Moreau 
(19641, and includes Madagascar, the Mascarene Islands  bunion, Mauritius 
and Rodriguez), and other oceanic islands in the western Indian Ocean to a s  
f a r  north as  the Seychelles. The term Aldabra archipelago includes Aldabra, 
Assumption, Cosmoledo and Astove, though not Gloriosa. 
In general, the nomenclature, both scientific and English, follows that of 
Watson, Zusi and Storer (1963). Subspecific names a r e  not used except where 
they seem to have been reasonably satisfactorily established. English names 
a r e  the equivalent of scientific specific, rather than subspecific, names. 
A sign "0" indicates an unsexed specimen. The average of measurements 
is often given in brackets following the extremes. 
It should be well-known that Bergmann's Rule is to the effect that in warm- 
blooded vertebrates the smaller-sized geographic forms of a species a r e  
found in the warmer parts of the range, the larger-sized in the cooler parts 
of the range. 
(1) Land Birds 
(a) Bveeding Residents (ov pyesumed so) 
Dawson (1966a, 7) records the Indian Reef Heron Demiegretta asha as  
breeding exclusively on Astove. But if this is so, i t  could also do so on Alda- 
bra. However, in  the absence of supporting details one cannot be convinced 
that it breeds even on Astove, especially a s  according to Watson, Zusi and 
Storer (1963, 24) it is not known to breed otherwise nearer to Astove than 
Ceylon. It may also be mentioned here that Vesey-FitzGerald (1940, 488) 
found the Madagascar Grass-Warbler Cisticola cherina abundant on Cos- 
moledo and Astove, though he did not see  i t  on Aldabra. Unfortunately the 
specimen which he collected and sent to the British Museum cannot be traced. 
Ardea cinerea cinerea Linnaeus Grey Heron 
---
According to Abbott (in Ridgway 1895, 530), this species breeds on Alda- 
bra, and nests wlth young were seen in November. One specimen was col- 
lected, and likewise by Voeltzkow (Berlepsch 1899, 495). Nicoll (1906, 695) 
records it from both Aldabra and Assumption. Morris (1963) saw a few on 
Aldabra, hut Bourne (1966) records "hundreds". Dupont (1907) lists it from 
throughout the archipelago. 
Benson (1960a, 31) considers that two specimens from the Comoros a r e  
better placed with A. c. cinerea than _A. c. f irasa Hartert of Madagascar, the 
latter distinguishable by longer measurements for  the culmen and tarsus 
(respectively 131 - 145 as  against 110 - 133, and 185 - 200 as  against 155 - 
182 mm.). He thought that four immature specimens from Aldabra and As- 
sumptlon were also best placed with A. c. cinerea, though possihly not fully 
grown. Berlepsch (1899, 495) gives the wing of Voeltzkow's specimen as  465, 
culmen 140, tarsus 165 mm. The tarsus measurement is well within the 
range of A. c. cinerea. That for  the culmen agrees better with A. c firasa, 
but may have been taken from the base of the skull instead of the end of the 
frontal feathering a s  in Benson's measurements. A specimen in Cambridge 
from the Amirante Islands, collected in December 1864, has wing 424, cul- 
men (from frontal feathering) 120, tarsus 170 mm., thus agreeing with A. c. 
c-a. It is concluded that the populations frequenting al l  of the above- 
mentioned islands a r e  best attributed to this subspecies, and a r e  accord- 
ingly of African rather than Madagascan origin. 
Butorides striatus crawfordi Nicoll Little Green Heron 
B. s. crawfordi, of which I have seen the type, an adult male in the British 
-- 
Museum from Assumption, and another adult male therein from Aldabra, can 
easily he distinguished from g. 2. rhizophorae Salomonsen, of the Comoros, 
by the paler grey of the underside. I have also been lent the specimen col- 
lected by Abbott on Aldabra (Ridgway 1895, 531). It is a male in immature 
dress, and cannot be used in considering subspecific differences based on 
colour. The same applies to a female in Par is  collected on Aldabra by Cher- 
bonnier, which I have also seen. But al l  four specimens a r e  smaller  than 
rhizophorae, see  below. Presumably there is the same sexual colour dif- 
ference in the adult of crawfordi as in rhizophorae and 2. _s javanicus 
(Horsfield), that is, the female has the sides of the neck, chest and abdomen 
washed with brown, and the spotting on the throat more strongly pronounced 
(Benson 1960a, 34). 
Benson (1960a) gives the wing-length of 16 specimens of rhizophorae a s  
170 - 180 mm. Thirteen specimens in London, Paris  and Cambridge from 
Reunion, Mauritius and Rodriguez, doubtfully separable from the Asiatic 
javanicus, measure 167 - 181 mm. On the other hand, 10 specimens from the 
Seychelles (Mah6, Cousin, Praslin, La Digue), attributable to B. s. degens 
Hartert, measure 159 - 168 mm. only. Like degens, crawfordiis  alsosmall ,  
a s  the following figures show: 
Adult 8 159, 161 mm, 
Immature o" 159 mm. 
Immature ? 157 mm. 
An immature male collected by Voeltzkow which I have been lent has wing 
152 mm., and may not be quite fully grown. This certainly applies to an im- 
mature specimen in Cambridge from the Amirantes, with wing 140 mm. only. 
Benson (1960a, 34) accepts the contention of White (1951, 460) that rhi- 
zophorae is of Asiatic origin, and there is no reason to suppose that this does 
not also apply to crawfordi. On the other hand, - B. - s. rutenbergi (Hartlaub) of 
Madagascar is very close to - B. - s. atricapillus (Afzelius) of Africa, whence 
White suggests that degens of the Seychelles is also derived. 
Abbott (in ~ i d ~ w a y 5 ,  531) found this species quite common on Alda- 
bra, breeding among mangroves in November and December, laying two 
eggs. Probably the breeding season is fairly extensive, since in the Comoros 
Benson (1960a, 35) obtained data pointing to egg-laying in August and Septem- 
ber. Abbott also noted that the birds stand for hours on the backs of turtles, 
catching the blue-bottle flies which swarm on the turtles' backs and heads. 
Dupont (1907) l is ts  this species from throughout the archipelago. 
Egretta garzetta dimorpha Hartert Little Egret 
E. dimorpha has often been regarded as  a full species, a s  by Watson, 
~ u s i a n d  Storer (1963). However, I s ee  no reason to differ from the opinion 
of Grant and Mackworth-Praed (1933) and Berlioz (1949, 20), for  example, 
that dimorpha is conspecific with E. garzetta. Dimorpha inhabits Madagas- 
c a r  and the Aldabra archipelago, and is notable for  the common occurrence 
of a dark blue-grey phase as  well as  a white phase. A grey phase also occurs 
in coastal eastern and north-eastern Africa and in coastal West Africa 
(White 1965, 25), but is r a r e  o r  quite absent in the interior of Africa. Grant 
and Mackworth-Praed (1933) have separated the populations of Aldabra and 
Assumption as  E. g. assumptionis, differing from dimorpha by its longer bill. 
- - 
This was on the basis of material in  the British Museum. There is no further 
material available therein. While due note must be taken of this difference, 
the measurements presented show an appreciable overlap. On existing evi- 
dence it is difficult to justify recognition of assumptionis. 
Abbott (in Ridgway 1895, 530, under Demigretta gularis) found this the 
commonest heron on Aldahra, and breeding in large numbers in  December, 
laying from two to four eggs. The white phase was twice o r  thrice as  num- 
erous a s  the blue. Nicoll (1906, 696, 704, under Demiegretta sacra)  collected 
it on both Assumption and Aldabra, finding it extremely abundant on the 
latter. A specimen collected on Aldabra was partially white and dark. I can 
confirm that this applies to both this and another specimen from Aldabra, 
both in the British Museum. Morris (1963) found both phases plentiful on 
Aldabra. Bourne (1966) records hundreds, of which about forty per cent 
were in the dark phase. He also records i t  from Cosmoledo, where the 
phases were about equal, while one "White-faced Heron" was seen on Astove 
(presumably this was a specimen of E. g. dimorpha in the dark phase, in 
-- 
which the chin and throat a r e  still  white). He gives no record from Assump- 
tion, and possibly i t  has been extirpated there. Dawson (1966a, 7) records 
large flocks on Cosmoledo, Astove and Aldahra, the proportion of light to 
dark birds being about seven to three, with the occasional intermediate pie- 
bald. 
Milon (1959) found that in  two breeding colonies in Madagascar selected 
for study the ratio of the dark phase to the white phase was about 35: 65. The 
observations from the Aldabra archipelago tend roughly to bear this out. 
Threskiornis aethiopica abhotti (Ridgway) Sacred Ibis 
This species occurs in Africa (T. -- a. aethiopica (Latham)), Madagascar 
(T. -- a. bernieri (Bonaparte)) and Aldahra (T. a. abbotti). The characters on 
--  -
which these three subspecies can be recognised may be summarised a s  
follows (it should here  be mentioned that immature specimens of all three 
have the head and neck feathered, whereas in adults these areas a r e  bare): 
Feathering on head and neck (in immature): In aethiopica and bernieri 
white heavily streaked black; in abhotti black streaking much reduced, and 
only on a few feathers. (Only one immature specimen of abhotti was avail- 
able. But the diffkrence was striking, and shows up well in three photo- 
graphs in Nicoll (1908).) 
Decomposed tertials: Glossy purplish slate in aethiopica, bluish slate 
in bernieri, much paler than in aethiopica; bluish slate in W i ,  a s  in 
bernieri, but darker. 
Metallic green tips to remiges: Extending back 40 - 60 mm. in aethiopica; 
not more than 15 mm. in hernieri, in three out of eight specimens absent; not 
more than 10 mm. in abborti, in  four out of six specimens absent. 
Ir is  (in adult): Brown in aethiopica (see for example McLachlan and 
Liversidge 1957); white in bernieri; bluish-white in B.(The difference 
between bernieri and abbotti is a s  given by Ridgway 1895, 530, and is con- 
firmed from the labels of one adult specimen of the former and two such of 
the latter. An immature specimen of abbotti had the iris very dark brown.) 
Ridgway also suggests that the lower half of the neck is entirely naked in 
abbotti, but not s o  in bernieri. I cannot convince myself that the extent of 
-
feathering up the neck is not variable in the adult of al l  three subspecies, and 
that it can be used a s  a distinguishing character. Ridgway further suggests 
that the tips to the remiges differ in colour, but i t  seems that there is only a 
difference in i ts  extent. 
Presumably bernieri was derived from aethiopica, and probably abbotti 
from bernieri rather than aethiopica. The colour of the decomposed tertials, 
the reduction of the dark tips to the remiges, and the colour of the iris all 
suggest a closer relationship of abbotti to bernieri than to aethiopica. 
The following a r e  measurements in  mm. of the material of bernieri and 
abhotti studied, in London, together with two specimens of bernieri in 
-
Cambridge: 
Culmen from 
Wing base Tarsus 
Bernieri 
Adult 3" 374 169 95 
Adult 9 9 342 348 362 132 137 144 72 76 82 
Immature 6 357 182 84 
Immature 9 7 334 340 136 143 74 78 
Immature 0 371 broken 87 
Abbotti 
-
Adult 9 9 336 340 125 132 76 76 
Adult 0 335 337 338 125 133 136 70 70 72 
Immature 6 347 176 80 
These figures do not suggest any marked difference between the two sub- 
species. Evidently males a r e  longer billed in both. 
Falco newtoni aldabranus Grote Madagascar Kestrel 
It is presumed that Madagascar, inhabited by - F. - n. newtoni (Gurney), has 
been the source of origin for  the populations elsewhere in the Malagasy Re- 
gion, namely F. punctatus Temminck of Mauritius, F. & aldabranus of Alda- 
bra, and F. a$ea (Oberholser) of the Seychelles. A single unsexed specimen 
of aldabranus (judging from its  wing-length) from Anjouan, in the Comoros, 
is considered by Benson (1960a, 39) to have been a stray from Aldabra, but is 
discussed further below. Failure to colonise the Comoros may be because the 
islands a s  a whole were probably originally almost wholly covered with ever- 
green forest  (Moreau 1966, 346). In Madagascar, Rand (1936, 378) found the 
species everywhere except in heavy forest. 
Benson (1960a, 39) studied to some extent the material in London. It has 
been re-examined, 13 specimens in Cambridge have also been considered, 
and wing-lengths taken of three specimens of aldabranus collected by Cher- 
bonnier, in Paris. Material of F. araea in London, Par is  and Cambridge has 
also been considered. 
From field observations, Gaymer tells me that the male of F. n. alda- 
branus is more brightly coloured than the female. I cannot make any personal 
judgment in this matter, since the only two specimens examined after I had 
hy the very distinctively coloured 2. mayottensis Schlegel, and Grand Comoro 
by Lwo forms considered of Africanoiigin. - Z. - m. maderaspatana of Madagascar 
exists undifferentiated on Gloriosa, and perhaps also on Cosmoledo and Astove 
(Moreau 1957, 402), but material is insufficient to decide the point for certain. 
Curiously, the family is apparently unrepresented on Assumption. - Z. - m. 
aldabrensis differs only from nominate maderaspatana in  being yellower above, 
and relatively longer tailed and shorter winged. Measurements in mm. of two 
males which were not available to Moreau (1957, 428), the f irst  in Cambridge, 
the second collected by Gaymer, a r e  as  follows: 
Wing Tail Culmen from base 
52 40 11.5 
Gaymer has provided the following further particulars for his speci- 
men: hill, upper mandible charcoal grey, lower pale blue-grey; legs pale blue- 
grey, likewise feet, with lemon soles; iris light brown, pupil with dark hlue 
sheen; weight 6.5 gms. 
In conclusion, aldabrensis was presumably derived from Madagascar, via 
Cosmoledo and Astove rather than via the Comoros. 
Foudia eminentissima aldabrana Ridgway Red-headed Forest Fody 
The details which follow in this paragraph a r e  derived from Moreau (1960), 
the characters of aldabrana being confirmed f rom personal examination of 
material. In Madagascar and the Comoros this ploceine genus, confined to the 
Malagasy Region, is represented by two species, F. eminentissima Bonaparte 
inhabiting evergreen forest and F. madagascariensis (Linnaeus) in drier, more 
open country. On Mauritius t h e r e i s  an analogous segregation between F. rubra 
- -  (Gmelin) and madagascariensis. The former is the local representative of 
eminentissima, from which i t  differs mainly by i ts  more slender, insectivorous 
type of beak. Other, more distinct, species inhabit Rodriguez (F. flavicans 
Newton) and the Seychelles (E. sechellarum Newton). ~ a d a ~ a s z r i e n s i s  is also 
known from the Amirantes and the Seychelles, but outside Madagascar may he 
a recent introduction by human agency, and shows no subspecific variation. 
Eminentissinla is otherwise only known from Aldahra, and the genus is unknown 
on Assumption, Cosmoledo, Astove o r  Gloriosa. F. e. aldahrana is a well 
- - 
marked subspecies, presumably derived from the Comoros, each island of 
which has i t s  own subspecies. In - F. - e. algondae (Schlegel) of Mayotte, the driest 
of the Comoros, the male has the red of the head l e s s  crimson, more orange in 
tone than on the other three islands. This is accentuated still further in 
aldahrana, and may be connected with a still drier ,  l e s s  shady environment. 
~ l s o ,  melanin in the contour feathers is l e ss  intense, so that the ground-colour 
of the streaky back is paler, and the olive-grey of the underside is replaced 
by pale dull yellow. Two males which have been available to me have the olive 
of the mantle largely replaced by red, and Benson (1960a, 100) notes that most 
Comoro males have a few crimson feathers to he found in part of the plumage. 
The hill of aldahrana is stouter than in any other subspecies, possibly in 
adaptation to a seed rather than an insect diet. 
According to Moreau (1960, 38), and s e e  also Benson (1960a, 101), i t  is 
uncertain whether in the humid Comoro environment there is a dull nonbreeding 
plumage. However, Morean (1960, 34) quotes Rand that there is in F. e. omissa 
Rothschild. As to Aldabra, a male in Cambridge collected by Abbott in October 
is in breeding dress ,  the r ed  fully developed. This is also confirmed by Ridgway 
(1895, 538), who quotes Abbott that nesting takes place in November, December 
and January (and see also Bendire 1894). Two males  collected by Gaymer on 14 
and 30 November a r e  in breeding dress,  as a r e  four collected by Nicoll in mid- 
March. Nicoll (1908, 116) also indicates that there were many such birds a t  the 
time of his visit, while Morr i s  (19631, who visited Aldabra in January and Feb- 
ruary, f rom his  account obviously also saw males  in breeding dress.  However, 
two males lent to me, collected by Cherbonnier on 12 and 20 May, a r e  strik- 
ingly different. The f i r s t  has  no sign of red, the second has a small  amount on 
the head and chest. No less remarkable i s  i t  that in hoth the olive tones of the 
mantle a r e  replaced by rufous brown, this also being the coloration of the 
crown (obscurely streaked with dusky) and the rump. The chin, throat and 
abdomen a r e  dull yellow, of the same tone as on the abdomen of males in 
breeding dress ,  and there is a heavy brownish wash across  the chest and on 
the flanks. Also, the bill, instead of being black, is dark brown in the f i r s t  
specimen, paler horn in the second. Two females collected by Cherbonnier in 
May, which 1 have also been lent, a r e  s imi lar  to the f i r s t  male, in their rufous 
brown tones above and brownish wash on the chest  and flanks. But a female 
collected by Nicoll on 14 March has olive tones above, and the whole underside 
dull yellow, with some olive (not brownish) wash ra ther  strictly confined to the 
flanks. A l l  three of these females  have the bill horn coloured. There a r e  two 
further  specimens collected by Gaymer on 14 November, s imilar  in all respects  
to Nicoll's female. One is sexed a s  a male, the other  a s  a female. But s e e  the 
measurements  below, they have wings 78, 80,tails both 53 mm. Thus they seem 
to be both males, and to have failed to develop into breeding dress. They a r e  
placed accordingly in the measurements.' 
It s eems  c lear  that, whatever may he the situation in the humid Comoros, 
on Aldabra there a r e  well-marked seasonal plumage changes in both sexes, 
the colour of the bill of the male  also changing. 
Moreau (1960, 35) gives measurements fo r  only four males of aldabrana, 
and i t  is worth giving them for  all  of the material  now examined (in mm.): 
Wing Tail  Culmen from base 
11 d 3 78 - 84 (80.3) 48 - 57 (52.5) 17 - 20.5 (18.6) 
3 9 $ 72 74 74 43 47 47 18 18.5 20 
The tail/wing ratio for  males  works out a t  65, the same figure as arr ived a t  
by Moreau. It is curious that, although males  have longer tails and wings than 
females, the bill measurements a r e  s o  similar.  The Comoro f igures in Benson 
(1960a, 100) show a sexual disparity in all three s e r i e s  of measurements. How- 
' Gaymer states, however, that the specimen with wing 80 mm. was a female with large 
gonads - Editor. 
ever,  only three females of aldabrana were  available. Nevertheless, neither is 
there any indication from the further f igures given below of any difference in 
the bill. 
Gaymer gives the weights of the four specimens which he collected a s  21, 
24, 25, 26 gms. The following summary has been compiled from figures in mm. 
supplied hy him fo r  specimens mist-netted and subsequently released, all  
caught in November: 
Wing Tail Culmen (exposed part) Notes 
Notes: (a) in breeding dress.  
(b) in female-like dress,  bur showing t r aces  of r ed  in plumage, so  presumably males. 
(c) wholly in female-like dress ,  bur those in second s e r i e s  perhaps roo long-winged ro 
be females. 
Weights in gms. of these four s e r i e s  were respectively a s  follows: 22.5 - 27 
(25.7): 24, 25.5, 27.5, 27.5; 21 - 27.5 (24.8); 23 - 27.5 (24.9). 
(b) Mig~ants 
(i) Already recorded 
Porzana marginalis Hartlaub Strip Crake 
There is a male in the American Museum of Natural History, collected by 
F. R. Mort imer on West Island (Ile Picard), Aldabra, 10 December 1904 
(Benson 1964, 56). This occurrence may be considered a s  accidental, and is 
the only record known to me from the Malagasy Region. Benson (1964, 56) has  
presented data suggesting that this species i s  migratory in southern Africa, 
only normally present during the rains, when i t  breeds. This particular speci- 
men was probably blown off course on southward migration. 
Squatarola squatarola (Linnaeus) Grey Plover 
Collected by Nicoll (1906, 703, under the name S. helvetica) on Aldabra, and 
reported a s  common. At least  one seen by Morr is  (1963). Probably regular 
f rom late  September to early April, a s  in Madagascar (Rand 1936, 3511, and s e e  
also Benson (1960a, 43) for  the Comoros. 
Charadrius leschenaultii Lesson Great  Sand Plover 
Collected by Abbott on Aldabra, and noted a s  "rather common'' (Ridgway 
1895, 527, under the name Aegialitis geoffroyi). There is also a specimen in the 
British Museum collected in 1906. Seen by Morr is  (1963). Dupont (1907) l i s t s  i t  
f rom throughout the archipelago. Rand (1936, 354) found i t  fairly common in 
Madagascar f rom September to early May, and Benson (1960a, 43) found i t  on 
all  four islands in the Comoros. 
Numenius phaeopus phaeopus (Linnaeus) Whimbrel 
Collected by Abbott on Aldahra, recorded a s  common (Ridgway 1895, 528). 
Also collected there by Voeltzkow (Berlepsch 1899, 494). Dupont (1907) l i s t s  
both N. phaeopus and N. madagascariensis (presumably meaning N. arquata) 
from>hroughout the archipelago. F r y e r  (1911. 420). who was in the archipelago 
. . 
from August to February, staces that both N. phaeopus and arquata were abun- 
dant. However, in Madagascar and the ~ o m < r o s  the former  outnumbers the 
lat ter  (Rand 1936, 348; Benson 1960a, 44). Bourne (1966) records hundreds of 
"curlews" Numenius sp. A solitary "curlew" seen by Morris  (1963) may also 
have heen - N. phaeopus. 
Numenius arquata orientalis Brehm Curlew 
Under the heading N. madagascariensis,  though presumably N. arquata was 
intended, found by Abbztt to  be not common, though no specimenwas collected 
(llidgway 1895, 527). See also other possible records  under N. phaeopus. N. a. 
- - 
orientalis has been collected in the Comoros (Benson 1960aT44), and the occur- 
rence of N. a. arquata (Linnaeus) s eems  unlikely, s e e  especially Rudebeck 
(1963, 499-501). 
Tringa nebularia (Gunnerus) Greenshank 
--
A specimen collected by Abbott on Aldahra (Ridgway 1895, 527) appears  to 
be the only record  from anywhere in the archipelago, other than the listing of 
i t  f rom throughout by Dupont (1907, under the name T. glottis). It may not be 
-- 
s o  very uncomnlon, for  Benson (1960a, 44) gives a number of records  f rom the 
Comoros, including one of a flock of 40, and Rand (1936, 349) found i t  in Mada- 
gascar  f rom late  November to early March. 
Tringa glareola Linnaeus Wood Sandpiper 
One specimen collected by Abbott on Aldabra, and he noted i t  a s  "rather 
scarce"  (Ridgway 1895, 527). This appears  to be the only record f rom the 
Malagasy Region, s o  that i t  must have been an accidental occurrence. This 
species per fers  inland marshes  to sea-coasts, 
Actiris hypoleucos (Linnaeus) Common Sandpiper 
One specimen collected by Abbott on Aldahra, hut he found i t  "not common" 
(Ridgway 1895, 527). Dupont (1907) l is ts  i t  f rom throughout the archipelago. It 
may not be r a re ,  for  Benson (1960a, 44) found i t  fairly common in the Comoros, 
Rand (1936, 349) records  i t  from August to March in Madagascar, and i t  is even 
abundant and regular on Reinion and Mauritius (Berlioz 1946, 35). 
Arenaria in terpres  in terpres  (Linnaeus) Turnstone 
Collected by Abbott on Aldabra, where very  common (Ridgway 1895, 527). 
Also collected there by Cherbonnier in May. Recorded by F rye r  (1911, 420) as 
abundant in the archipelago throughout his stay, f rom August to February. In 
March 1964 thousands were seen on Aldabra, also la rge  numbers on Cosmoledo 
and 100 on Assumption (Bourne 1966). Dupont (1907) l is ts  i t  f rom throughout the 
archipelago. Rand (1936, 351) found i t  fair ly common in Madagascar, f rom late  
September to early May, while Benson (1960a, 43) gives various records f rom 
the Comoros. 
Crocethia - alba (Pallas) Sanderling 
Collected by Abhott on Aldahra, said to be common (Ridgway 1895, 527, 
under the name Calidris arenaria).  Nicoll (1906, 704), in dealing with the next 
species, mentions seeing i t  there, and (1908, 118) saw "a few". Although Benson 
(1960a, 44) gives only two records  f rom the Comoros, Rand (1936, 350) found i t  
fair ly common in Madagascar f rom late  September to early March. 
Erolia testacea (Pallas) Curlew Sandpiper 
Abbott records  a small  flock, and collected two specimens (Ridgway 1895, 
527, under the name Tringa ferruginea). Nicoll (1906, 704, under T. subarquata) 
-- -
saw several ,  and collected a specimen. Five "dunlins" seen by Morr is  (1963) 
were probably this species. Benson (1960a. 43, under Calidris ferruginea) 
gives a few records from the Comoros, and Rand (1936, 349) found i t  fairly 
common from October to early March in Madagascar. 
Eurystomus glaucurus glaucurus (Miiller) Broad-billed Roller 
At leas t  four specimens have been collected on Aldahra: one in November 
1906 (Benson 1960a, 55); one by Abbott on 10 December 1892, and one by 
Mortimer on 24 December 1904 (Benson 1963a); a female by Gaymer on 9 De- 
cember 1964, wing 197 mm. Abbott (in Ridgway 1895, 534) was informed of 
several  others  previously seen there. Vesey-FitzGerald (1940, 488) saw one on 
Cosmoledo, 6 October. There a r e  a t  leas t  four specimens from the Comoros, 
one of which is dated 7 November, one 10 April, the others being undated 
(Benson 1960a, 55; 1963a). 
According to Moreau (1966, 249-250), this subspecies (there a r e  two other, 
smaller ,  ones which breed in Africa, s e e  White 1965, 237) is present in Mada- 
gascar  from October to March, breeding in October and November. The main 
"winter" quar te rs  a r e  probably in the Congo. Records from Malawi and Zambia 
a r e  all  for  October-November and February-April, suggesting that the birds 
a r e  only on passage through these terr i tories .  This must also apply to the 
Aldabra, Cosmoledo and Comoro records.  Such a passage may he regular  in 
small  numbers. 
Apus apus apus (Linnaeus) Eurasian Swift 
---
Abbott collected a specimen on 1 December (Ridgway 1895, 534) which I 
have been lent. It agrees with material  in the British Museum of nominate apus 
-
ra ther  than of A. a. pekinensis (Swinhoe). The label is endorsed "The only one 
- -  
observed - undoubtedly accidental straggler". This appears to be the only 
record of the species from the Malagasy Region, though it is plentiful as a 
visitor to southern Africa, whence there is no lack of material of hoth sub- 
species (Irwin and Benson 1966, 15). 
Riparia r iparia  r iparia  (Linnaeus) Sand-Martin 
---
One was collected by Abbott on Aldabra on 2 December, another by him on 
Gloriosa on 29 January (Benson 1963a). Although this is a common palaearcdc 
migrant to southern Africa, i t  is probably merely casual in the Malagasy Region, 
the only other record traced being a specimen f rom Lac Iotry, Madagascar 
(Rand 1936, 427). 
Phedina borbonica madagascariensis Hartlaub Mascarene Martin 
Abbott collected a specimen on Aldabra on 19 November, listed by Ridgway 
(1895, 535) a s  P. borbonica, and fur ther  reported on by Benson (1963a). No 
doubt i t  was on passage, even though the breeding season in Madagascar in- 
cludes October and November (Moreau 1966, 252). A s  Moreau points out, the 
movements of this bird a r e  not understood. Small numbers have been reported 
f rom Pemba Island in September-March, prior  to 1930. The only other African 
record is from Lake Chilwa, Malawi, where hundreds were seen between 28 
June and 30 July 1944. 
Motacilla flava lutea (Gmelin) Yellow Wagtail 
--
Abbott collected a male on Aldabra on 20 December (Ridgway 1895, 535, 
under M. campestris).  It is evidently by a slip of the pen that Watson, Zusi  and 
Storer  (1963, 198) place this record under the Tawny Pipit Anthus campestris.  
I have been lent this specimen, the label of which is endorsed "accidental 
visitor". Indeed this seems to be the only record of the species from the Mala- 
gasy Region. The specimen is in full adult d re s s ,  except f o r  some brownish 
feathers  on the underside. It has the crown mainly green, with yellow restr icted 
to the fore  part  and the forehead, and a well-developed yellow eyestripe. Thus 
in colour it agrees  with the description by Vaurie (1959, 75, 78) of M. f. fla- 
v-a Blyth rather  than m. However, the view of Dowsett (1965) that such 
specimens f rom eastern Africa a r e  individuals of lutes showing the charac ters  
of flavissima is accepted, and applies also to Abbott's specimen. 
Muscicapa sp. Flycatcher 
Under this beading Abbott ( in Ridgway 1895, 535) mentions seeing a small  
grey flycatcher with white rump on Aldabra in December. It is impossible to 
make any suggestion a s  to the identity of this bird, which might not have been 
a muscicapid at all. 
(ii) Not yet recorded, but likely to occur 
Ardeola idae (Hartlaub) Madagascar Squacco Heron 
-- 
According to Moreau (1966, 249), this species is said to breed in Madagascar 
in the rains, and occurs in tropical eastern Africa as an off-season visitor 
during May to October. Benson (1960a, 34) collected i t  on Mayotte, in the 
Comoros, in October, presumably on passage back to Madagascar. It is likely 
to occur also on Aldabra on passage. 
Falco eleonorae ~ 6 n 6  Eleonora's Falcon 
Ii-o concolor Temminck Sooty Falcon 
According to Moreau (1966, 68) these two species winter entirely in Mada- 
gascar. Nicoll (1906, 680) records a specimen of F. subbuteo from Mayotte, in 
the Comoros, but i t  may well be an eleonorae  enson on 1960a, 105). There is an 
undated specimen of E. concolor f rom Tanga, in coastal north-eastern Tanzania, 
in Pa r i s ,  and Reichenow (1900, 630) gives two other records of this species 
f rom eastern Tanzania, and one from Mozambique. Both these palaearctic 
breeders  may well pass over Aldabra. 
Charadrius hiaticula tundrae (Lowe) Ringed Plover 
Rand (1936, 352) records  i t  f rom Madagascar during December to March, 
and Benson saw i t  regularly f rom la te  August until he left the Comoros in late 
November. It may well be regular on Aldabra. 
Limosa lapponica lapponica (Linnaeus) Bar-tailed Godwit 
Since Rand (1936, 349) re fers  to i t s  occurrence in the Seychelles and Mada- 
gascar ,  i t  presumably occurs occasionally on Aldabra. 
Tringa totanus (Linnaeus) Redshank 
--
A record by Dupont (1907, under the name T. glottis) for  the Greenshank 
-- 
T. nebularia has already been r e fe r r ed  to under that species. Dupont also 
l i s t s  T. nebularia, which he cal ls  "Redshank", from Aldabra. It would seem that 
t h e r e x a s  been a cler ical  e r ro r ,  and that both records  re fer  to the Greenshank 
T. nehularia. Watson, Zusi and Storer  (1963, 30) do not give any occurrence of 
T. totanus nearer  than the Maldives. It is t rue  that Dawson (I963a, 7) mentions 
-- 
i t  f rom the Seychelles. But i t s  occurrence anywhere in the western Indian 
Ocean south of the equator requires proper substantiation, and moreover 
Rudeback (1963, 492) finds that south of 1 0 ' ~ .  in Africa i t  is sca rce  and 
irregular .  
The necessity for  the inclusion of this species has ar isen from Dupont's 
apparent cler ical  e r ror .  It can only be extremely r a r e  on Aldabra. 
Xenus cinereus (Giildenstaedt) Terek Sandpiper 
Rand (1936, 348) found i t  not uncommon in Madagascar, and there is even a 
specimen in Cambridge from Mauritius, collected on 13 January 1864. Benson 
(1960a, 44) gives one record from the Comoros. Its occasional occurrence on 
Aldabra is very probable. 
Erolia minuta (Leisler)  Little Stint 
--
Newton (1867, 343) found i t  common on Mahk, in the Seychelles, and there 
is a specimen collected there by him in Cambridge. Benson (1960a. 44) col- 
lected one on Grand Comoro, and Rand (1936, 350) gives one record from 
Madagascar. It must occur occasionally on Aldabra, but i ts  listing by Dupont 
(1907, under T a  minuta) -from throughout the archipelago requi res  confir- 
mation. 
Glareola ocularis  Verreaux Madagascar Pratincole 
Glareola maldivarum Fors t e r  Eastern Collared Pratincole 
Moreau (1966, 251) r e f e r s  to Galacbrysia nuchalis, no doubt real ly meaning 
Glareola acularis,  as quite common in coastal Kenya in August and September. 
Benson (1960a, 45) collected a specimen on Mayotte, in the Comoros, on 28 
October. A.  D. Forbes-Watson tells me he saw one on the Dzaoudzi airs tr ip,  
Mayotte, on 24 October 1965, and five days ear l ie r  three on the Moroni air- 
strip, Grand Comoro. Presumably all  these Comoro records r e fe r  to birds on 
delayed passage back to Madagascar. It is likely to also occur on passage on 
Aldabra. 
G. maldivarum, treated by Watson, Zusi  and Starer  (1963) a s  conspecific 
~ i t h ~ r a t i n c o l a ,  is known a s  an occasional visitor from the palaearctic to the 
Seychelles (Benson and Roux, in press)  and has also been recorded from 
Mauritius (Rountree and others  1952, 179). It could also occur on Aldabra. 
Cuculus canorus Linnaeus Grey Cuckoo 
Nicoll (1906, 700) saw a cuckoo on Aldabra which he thought was this 
species. Its occasional occurrence a s  a migrant from the palaearctic i s  poss- 
ible. Benson and Roux (in p re s s )  record such a specimen from Mah6, in the 
Seychelles. Abbott (in Ridgway 1895, 514) also gives a very probable record 
f rom Mahk, though he did not retain a specimen. 
Cuculus poliocephalus rochii Hartlaub Lesse r  Cuckoo 
According to Moreau (1966, 249), the Madagascar breeding subspecies is 
present in most of the island only from the end of September to April, and has 
been recorded from Kenya, Uganda, Tanzania, and the south-eastern Congo a s  
a non-breeding visitor from June to September. So f a r  there is no record f rom 
any of the intervening islands between Madagascar and eastern tropical Africa. 
But i t s  occurrence on passage, including Aldabra, is likely. 
Collocalia francica (Gmelin) Cave Swiftlet 
Abhott saw a Collocalia sp. on Aldabra severa l  t imes (Ridgway 1895, 535). 
Possibly the fo rm frequenting ~ a h 6 ,  in the Seychelles, C. f. elaphra Oberholser, 
occurs occasionally on Aldabra. The genus is only otherwise represented in 
the Malagasy Region on Mauritius and Rkunion, and i t s  status in Madagascar 
is problematical (Moreau 1966, 331). 
Merops superciliosus superciliosus Linnaeus Blue-cheeked Bee-eater 
A s  Moreau (1966, 251) indicates, this subspecies, which breeds in Madagas- 
c a r  (and in tropical eastern Africa), has fo r  long been regarded a s  a migrant 
between Madagascar and Africa. But he concludes that large-scale migration 
f rom Madagascar remains to he proved. However, i t  probably occurs occa- 
sionally a s  a wanderer on Aldabra, especially a s  it breeds on Mayotte, in the 
Comoros (Benson, 1960a, 59). 
* Hirundo rust ica Linnaeus Swallow 
--
J. H. Crook has a record  of i t  a s  a s traggler  to ~ & ~ a t e ,  in the Seychelles, 
in November (Lousteau-Lalanne 1962, 30). Rand (1936, 427) saw s ix  o r  seven 
a t  Tulear, Madagascar, in January. This  species is very plentiful as a visitor 
from the palaearctic lo southern Africa, and may he expected to occur occa- 
sionally on Aldabra. 
(c) Of  U n c e ~ t a i n  Status 
Bubulcus ibis (Linnaeus) Cattle Egre t  
The only definite record traced f r o m  Aldabra is of one seen by Abbott 
(Ridgway 1895, 531), though Gaymer s ta tes  that they a r e  a recent arr ival ,  and 
that in 1964 about 100 birds were roosting a t  Takamaka, in the eastern par t  of 
Aldabra. Bourne (1966) gives a record of s ix  seen on Astove. With any develop- 
ment of the atoll, a breeding colony could well become established. 
It is impossible to suggest whence the birds seen on Aldabra and Astove 
might have emanated. The nominate subspecies breeds in Madagascar (Rand 
1936, 332) and on Anjouan, in the Comoros (Benson 1960a, 33), while the popu- 
lations of the Amirantes and the Seychelles may have to be known a s  - B. - i.
seychellarum (Salomonsen), despite the s t r ic tures  on i t s  validity by Dawson 
(1966h). As pointed out by Benson (1960a. 33), two of the specimens on which 
Salomonsen based his description a r e  f rom the remote Bird Island, in the 
Seychelles. The third, in Par i s ,  which I examined in 1966, is from Ile Cousine, 
and i t s  wing measures 236 mm. only. Unfortunately the buff coloration is con- 
fined merely to a t race  on the forehead, and I found i t  impossible to decide 
whether i t  was more golden cinnamon, a s  claimed for  seychellarum, or  buff, 
a s  in the nominate form. 
Ridley and Percy (1958, 31, 45) found this species to he a serious predator 
of eggs on Desnoeufs Island, in the Amirantes, and to a l e s se r  extent on Bird 
Island. They suggest that i t  was introduced a t  some time, hut were unable to 
t race  when o r  from where. If i t  was introduced, i t  seems odd that Ahbott (in 
Ridgway 1895, 531) found i t  already plentiful in such remote places a s  Coetivy 
and the Amirantes 75 years  ago. It may have established itself unaided and have 
evolved into a recognisable subspecies. If so, the coloration of seychellarum 
suggests a derivation f rom the Asiatic B. i. coromandus Boddaert. If the Asiatic 
- - 
Ixohrychus sinensis could establish itself unaided in the Seychelles a s  would 
appear to he the case  (Benson, in preparation), there seems no reason why 
Bubulcus ibis should not also achieve this (and in the Amirantes). Further  
material  i G e q u i r e d  of the lat ter  species in o rde r  further  to assess the validity 
of seychellarum. 
Egretta alba melanorhynchos (Wagler) Great  White Heron 
--
Bourne (1966) r e fe r s  to egre ts  which were abundant on Cosmoledo, and 
were evidently E. garzetta. Also present were five la rger  white birds which 
could have be en^. - -  alba, though the description of the bottom of the feet a s  
orange is puzzling. One would expect the colour to be black, like the remainder 
of the feet and the legs. Bur be that a s  i t  may, i t  is likely that this species 
occurs occasionally a s  a wanderer, and might even establish itself,  i n  the 
Aldabra archipelago, a s  it breeds on Moheli, in the Comoros (Benson 1960a, 
32). 
Phoenicopterus ruber  -- roseus  Pal las  Greater  Flamingo 
Phoenicopterus minor Geoffroy Lesse r  Flamino 
Abbott (in Ridgway 1895, 529) collected five specimens of a flamingo on 
Aldabra, which he thought was a breeding resident, there probably being be- 
tween 500 and 1,000 birds on the atoll. But Nicoll (1906, 703) i n  his admittedly 
short  s tay did not s e e  any, and was also informed that there was no hreeding 
population. Dupont (1907, 23) records flamingos from Aldahra "all along the 
South East  and South on the shores  of the lagoon in numerous flocks of severa l  
hundreds". In his list  he c i tes  _P. erythraeus, presumed to be the same a s E .  
ruber  roseus. Possibly the specimen dated October 1906 in the British Museum, 
--
mentioned below, was collected by him, since Dupont was on Aldabra in that 
month. F rye r  (1911, 419) r e f e r s  to the presence of a resident population o fz .  
minor on Aldabra. According to Gaymer (1966), about fifty flamingos live in the 
southeast of the atoll, and probably breed there. He suggests that they belong 
to a new subspecies of P. r u b e .  Watson, Zusi  and Starer  (1963, 194) consider 
that five specimens (undoubtedly those collected by Abbott) appear aberrant,  
and r e fe r  them to P. ruber  subsp. 
Warson has most kindly lent me one of these five specimens, a male, con- 
sisting of a head and whole skin of the body a s  well. There is another such 
(unsexed) specimen in the British Museum, collected on Aldabra in October 
1906, par t  of a Howard Saunders Bequest. Their  measurements in mm. now 
follow, together with those of the other four specimens collected by Abhott, 
which Watson has been s o  kind a s  to supply (those of the f i r s t  male listed were 
taken by myself from the specimen which I was lent): 
S 3 V Y  
Wing 386 356 371 371 355 384 
Tail  140 135 134 133 130 138 
Ta r sus  245 253 265 255 235 275 
Culmen (exposed part) 120 115 118 110.5 116 122 
These figures agree substantially with those of _P. r. roseus provided by 
Witherby and others (1941, 166). The two Aldabra specimens personally ex- 
amined, compared to material  of this form from Africa in the British Museum, 
show no difference in ei ther  s tructure o r  colour. Both appear to be adult. The 
body-plumage of neither has any of the pink tinge said by Witherby and others  to 
characrerise adults, but severa l  other adults also lacked any such tinge. I t  may 
be that the colour varies  quite temporarily, according to the food available. 
Abbott gives the iris of the specimen which I was lent as straw-yellow, and this 
also agrees  quite well with Witherby and others  (1941), who give i t  as lemon- 
yellow. 
Rand (1936, 342) r e fe r s  a specimen from Lac Iotry, south-western Mada- 
gascar ,  to - P. - r. antiquorum (=E. r. roseus)  without any question, and he s ta tes  
that --  P. minor is very common there. Griveaud (1960) records  only P. ruber  
f rom Lac Iotry, estimating the numbers of flamingos there to be between 
25,000 and 30,000. The lower photograph on page 38 of his paper is certainly 
of a P. ruber, not a P. minor. 
Satisfactory as i t  would be in the cause of the conservation of Aldabra to be 
able to show that an endemic fo rm of Phoenicopterus exists there, I cannot find 
any such evidence. Dr Watson has also recently written to m e  to the effect that, 
despite the comment of Watson and o thers  (1963), he no longer considers 
Abbott's material separable from 5 r. roseus. Nor can I evenfindany definitive 
evidence of breeding on Aldabra. It may well be that both P. ruber  and e r  
do s o  occasionally, particularly a s  minor a s  well a s  a r  is said to occur in 
Madagascar. So f a r  the only report  of the occurrence of P. minor on Aldabra 
is f rom Fryer ,  but i t  is very possible that he confused i t  with e. It should 
be emphasised that both species seem highly nomadic and capricious in their 
places of breeding. Thus Brown (1957) records  attempted breeding by P. minor 
(a few ruber  were also present) in north-eastern Northern Rhodesia (now 
-
Zambia) in 1955. There is no other such evidence f rom Zambia, and the attempt 
was due to unusually dry conditions preceding (see also Benson 1963b, 627). 
Milvus migrans parasiticus (Daudin) Black Kite 
--
Abbott collected two specimens on Aldabra, on 2 October and 19 December, 
stating that kites a r e  occasionally observed but a r e  not common, while he a p  
parently saw i t  also on Gloriosa, which he visited in September (Ridgway 1895, 
525, 533). Nicoll (1906, 687; 1908, 102) saw this species on Gloriosa in March, 
and regarded i t  a s  non-resident. Its s tatus on Aldabra (and Gloriosa) cannot 
be regarded a s  certain, but presumably i t  is non-resident. Elsewhere in the 
Malagasy Region i t  is only known f rom Madagascar (Rand 1936, 381) and the 
Comoros (Benson 1960a, 36), where it is common. Rand saw an occupied nest 
in Madagascar in October. In southern Africa i t  is only normally present, a s  
a breeding visitor, from August to March; see fo r  example White (1965, 58). 
Although there is no definite evidence, i t  is reasonable to suppose that this 
also applies to Madagascar and the Comoros. If this is so, i t  could pass  through 
Aldabra on i t s  way to and from non-breeding quarters, perhaps in equatorial 
Africa. However, the dates of Abbott's specimens a r e  not in keeping with this. 
The possibility cannot be excluded that the odd pair  breeds on Aldabra, and 
perhaps also on Gloriosa. 
Dromas ardeola Paykull Crab  Plover 
Abbott saw "large flocks" on Aldabra, and collected two specimens (Ridgway 
1895, 527). It was also collected by Voeltzkow (Berlepsch 1899, 494). Nicoll 
(1906, 703) saw "enormous flocks" on Aldabra in mid-March. F rom observa- 
tions also made in March, Bourne (1966) records  "thousands" on Aldabra, and 
20 and 40 respectively on Cosmoledo and Assumption. Morris (1963), who made 
short visits in January and February to Aldabra, records merely "several" and 
"three". But he might have been unlucky, and not have visited a locality on the 
atoll where large numhers were congregated. Dupont (1907) lists i t  from 
throughout the archipelago. 
The status of this species on Aldabra is uncertain. But in view of the large 
numbers which have been reported it may well breed there. The nearest 
breeding locality to Aldabra which Benson (1960a, 45) was able to trace was the 
coast of former British Somaliland, though according to Watson, Zusi and 
Storer (1963, 115, 121) i t  may also do so in the Maldives and the Chagos 
Archipelago. 
Corvus albus Miiller Pied Crow 
--
This crow has presumably colonised the Malagasy Region from Africa, hut 
from the evolutionary aspect is of no interest, and no subspecies from through- 
out i ts  wide range has ever been proposed. It definitely breeds in Madagascar 
and the Comoros, and apparently also does so on Aldahra, Assumption and 
Gloriosa, though this requires confirmation f o r  Aldabra. It has also been 
recorded from Cosmoledo and Astove. 
Benson (1960a, 87) found i t  common throughout the Comoros. He saw nest- 
lings in early Novemher, and probably throughout i t s  range in southern Africa 
and the Malagasy Region it is essentially a pre-rains breeder. Abbott, who was 
on Aldabra from September to December, found it not common, likewise on 
Assumption, which he visited in September, yet plentiful on Gloriosa, visited 
in January and February (Ridgway 1895, 537, under C. scapulatus). While 
Abhott gives no evidence of hreeding on any of theseislands, Nicoll (1906, 689) 
was informed that i t  was resident on Gloriosa, saw empty nests on Assumption 
in March(1906, 693), while like Abhott he (1906, 700) found it uncommon on 
Aldabra, but was only there from 13 to 16 March. It does not appear in the 
catalogue of specimens collected by Voeltzkow (Berlepsch 1899). Vesey- 
FitzGerald (1940, 488) states that it is a visitor to Cosmoledo, Astove and 
Assumption, and nests on Aldabra, but gives no further details. Boulton (1960), 
who visited Aldabra in November 1959, records it, but gives no further infor- 
mation. Morris (1963), who visited the island twice in January and February, 
apparently did not see it. Gaymer collected a specimen on 5 December. Dupont 
(1907) l i s ts  i t  from throughout the archipelago. 
In the light of the foregoing, it is remarkable that, a s  a result of the visit 
of H.M.S. Owen in March 1964, while Bourne (1966) was unable to give any 
record from Assumption or Astove, and only one pair from Cosmoledo ("the 
f i rs t  for many years"), yet there were 'hundreds" on Aldabra. Clearly the 
status of this crow on Aldabra and neighbouring islands is in need of further 
investigation. Has it recently increased there, o r  is there perhaps some move- 
ment between the islands? It is my experience in  Africa that any extension of 
human settlement, with an increase in the availability of offal, favours it. The 
availability o r  otherwise of suitable tall t rees  a s  nesting sites may also be 
important (see for  example Benson 1953, 69). The statement by Vesey-Fitz- 
Gerald that i t  breeds on Aldabra should be confirmed, and in the meantime i t  
is best to include the Pied Crow among the species of uncertain status. 
(2) Sea Birds 
No doubt species additional to those now listed occur occasionally on o r  
around Aldabra, more especially representatives of the families Procellariidae 
and Hydrobatidae. Such possibilities can be found in Watson, Zusi and Storer 
(1963, 15-19). In the British Museum there is a specimen of Wilson's Petrel 
Oceanites oceanicus labelled a s  from Aldabra, November 1906. However, a s  i t  
is further stated on the label that i t  was collected at sea, a s  f a r  north a s  
"latitude 20M, it evidently was not obtained so very close to Aldabra. 
Phaetbon rubricauda rubricauda Boddaert Red-tailed Tropicbird 
Both Betts (1940, 504) and Vesey-FitzGerald (1941, 530) state that i t  breeds 
on Aldabra, but give no details. The lat ter  author also states that i t  breeds on 
Cosmoledo. It has been collected on Assumption (Ridgway 1895, 522; Nicoll 
1906, 697), and according to Ridgway, Abbott found i t  breeding there (and on 
Gloriosa). Dupont (1907) l is ts  i t  from throughout the archipelago. Gaymer in- 
forms me that he found a population probably numbering some hundreds, 
mainly along the northern part of the lagoon, breeding on small is lets  under 
rock ledges o r  bushes: he found a nest with one egg on November 18. Stoddart 
tells me that he saw a number on Aldabra when he was there in September and 
October 1966. 
Phaethon lepturus lepturus Daudin White-tailed Tropicbird 
Collected by Abbott and by Voeltzkow on Aldabra (Ridgway 1895, 532, under 
the name P. candidus; and Berlepsch 1899, 496, under P. flavirostris). Morris 
saw a pai r there  in January 1962, and 20 were seen in al l  in March 1964 
(Bourne 1966). 
Sula abbotti Ridgway Abbott's Booby 
-- 
There is no record of this species from Aldabra, and i t  is only known from 
Assumption and from Christmas Island (near Java). Unfortunately the breeding 
colony on Assumption was wiped out by labourers employed on guano extraction, 
and there is no record of i ts  occurrence there since 1936 (Betts 1940, 502). 
Vesey-FitzGerald (1941, 52) in fact gives the year of i ts  final extirpation as  
1926. 
Sula dactylatra melanops Heuglin Blue-faced Booby 
-
The only evidence of its occurrence on Aldabra is from Morris (1963), 
who saw both adults and immature birds. It has been collected on Assumption, 
while Abbott found a few breeding (Ridgway 1895, 520; Nicoll 1906, 697, under 
the name S. cyanops). Vesey-FitzGerald (1941, 521) doubted if i t  still  bred on 
~ s s u m ~ t i g n ,  due to the depredations of the guano labourers, though be also gave 
several islands on Cosmoledo Atoll as  breeding localities. Bourne (1966) rec- 
ords a few seen on Cosmoledo and Assumption. 
Sula sula rubripes Could Red-footed Booby 
--
Collected on Aldabra (Ridgway 1895, 531; Berlepsch 1899, 495, under the 
name S. piscatrix), where Abbott found i t  very abundant. Nicoll (1906, 704) also 
found it abundant; likewise on Assumption, where he collected two specimens 
and saw nests with young. There a r e  also specimens in the British Museum 
collected on Aldabra in October 1906. Vesey-FitzGerald (1941, 522) records 
nesting on islets in the lagoon of Aldabra, various islands in the Cosmoledo 
lagoon, and, before the start  of guano extraction, on Astove and Assumption, 
but gives no details. According to Dawson (1966a, 6), i t  breeds in mangroves 
on the northern r im of Aldabra, and in mangroves on the inner edges of the 
islands of Cosmoledo atoll, the nests being made of twigs. Bourne (1966) 
records three in all seen on Cosmoledo, and thousands of birds, probably 
mostly this species, seen feeding 10 miles to the north of Aldahra. Stoddart 
tells me that it was plentiful on Aldabra when he was there in September and 
October 1966, but in much smaller  numbers than the Frigatehirds. 
Sula - leucogaster Boddaert Brown Boody 
One was seen off Aldabra i n  March 1964 (Bourne 1966). No further evidence 
has been traced of the occurrence of this species anywhere in the archipelago, 
though it breeds in the Amirantes (Vesey-FitzGerald 1941, 521; Ridley and 
Percy 1958, 19, 30). 
Fregata minor aldabrensis Mathews Greater Frigatebird 
Fregata ariel iredalei Mathews 
-- 
Lesser  Frigatebird 
It is convenient to consider these two species together. Abbott collected F. 
minor on Aldabra, and found colonies of many thousands, with eggs 
November (Ridgway 1895, 522). He apparently saw both species, since there is 
mention of "all gradations of size between the two forms". It was evidently 
also F. minor which Voeltzkow collected, referred to by Berlepsch (1899, 495) 
a s  F. aquila. Nicoll (1906) makes no mention of frigatebirds on Aldabra, but 
- -  
saw F. aquila on Assumption, presumably also referring to F. minor. Vesey- 
-- -- 
FitzGerald (1941, 530) states that both species breed on Aldabra and Cos- 
moledo. Thousands of frigatebirds "of two sizes" were seen on Aldabra in 
March 1964 (Bourne 19661, and Stoddart informs me that they nest in very large 
numbers on the lagoon side of Middle Island, especially near East Channel. He 
also (Stoddart and Wright 1967a. 1175) describes them diving to drink on the 
wing at freshwater pools on South Island. Dupont (1907) l is ts  both species from 
throughout the archipelago. 
Lowe (1924, 308, 312) gives details of further specimens from Aldabra, in 
the British Museum and in the Rothschild collection at Tring. Those which were 
at Tring a r e  presumably now in the American Museum of Natural History, 
including the holotypes of aldabrensis and iredalei (Hartert 1925, 275). The 
only specimens from Aldahra traced in the British Museum a r e  the two of 
aldabrensis mentioned by Lowe. 
Larus  fuscus Linnaeus Lesser  Black-backed Gull 
--
Dawson (1966a, 8)  reports  a single bird seen f rom Aldabra, and this ap- 
pears  to be the only record f rom the Malagasy Region. Either this species 
o r  the southern L. dominicanus has been recorded from Beira, in coastal 
Mozambique ( ~ e ~ o n  1948, 151; Worth 1960, 173). But except in the hand, 
rhese two cannot be certainly distinguished f rom each other. Fuscus is much 
-
the more  likely on Aldabra. 
Hydroprogne caspia Pal las  Caspian Te rn  
There  is no record from Aldabra, but this species is mentioned on the 
strength of sight-records, both during October, f rom Astove and Cosmoledo 
(Vesey-FitzGerald 1941, 527). 
Sterna albifrons Pallas Little Tern 
Dupont (1907, under the name Sterna minuta) l i s t s  this species f rom 
throughout the archipelago. Dupont's records of S. halaenarum may also 
r e fe r  to S. albifrons. Bourne (1966) records  that7'thirty small t e rns  that 
might have been" this species were seen  off Assumption on 17 March. 
Gaymer informs me that he saw perhaps a hundred in November along the 
northern coast  of Aldabra, and rare ly  in the lagoon, and that i t  i s  locafly 
reported to breed. 
Sterna sumatrana mathewsi Stresemann Black-naped Tern 
Collected on Aldabra (Ridgway 1895, 526; Berlepsch 1899, 496; Nicoll 
1906, 704; in all these references under the name S. melanauchen). Thirty 
seen there in March 1964, likewise three on ~ s s u 6 p t i o n  (Bourne 1966). 
Sterna anaethetus antarctica Lesson Bridled Tern 
- -  
There  is no record from Aldabra, though Vesey-FitzGerald (1941, 526) 
s ta tes  that eggs have been found on limestone i s le t s  in Cosmoledo atoll in 
October. 
Sterna fuscata Linnaeus Sooty Tern 
--
"Rare in Aldabra", not collected (Abhott, in Ridgway 1895, 496); one speci- 
men collected by Voeltzkow on Aldabra (Berlepsch 1899, 496) (both notes under 
the name S. fuliginosa). Vesey-FitzGerald (1941, 525) s tates  that i t  breeds on 
Wizard ~ s z n d ,  Cosmoledo Atoll. 
Thalasseus bergii thalassinus (Stresemann) Crested Tern 
Abbott found i t  common on Aldabra, but did not collect a specimen (Ridgway 
1895, 526, under the name Sterna bernsteini). Mor r i s  (1963) saw terns  there 
which he thought were the next. species, T. bengalensis, but were perhaps e. 
Gaymer repor ts  frequently seeing i t  feeding a t  Aldabra, in shallow water over 
the outer reef  o r  in the lagoon, sometimes in smal l  groups, and states  that i t  
is locally reported to breed. Dupont (1907) l i s t s  both Sterna bernsteini and 
bergii f rom throughout the archipelago, but presumably refers  to the one 
-
species only, now known as T. bergii. There is also a possible record of three 
-- 
seen on Astove (Bourne 1966). Benson (1960a, 45) collected specimens in non- 
breeding d r e s s  in the Comoros during August-November, and records  one in 
breeding d r e s s  f rom Gloriosa, 10 March. 
Thalasseus bengalensis par  (Mathews and Iredale) Lesse r  Crested Tern  
-
There is no certain record from Aldabra o r  elsewhere in the archipelago, 
though Abbott collected a specimen on Gloriosa (Ridgway 1895, 524, under the 
name Sterna media), and there a r e  also specimens from the Comoros (Benson 
--
1960a, 45). 
Anous stolidus pileatus (Scopoli) Common Noddy 
--
Collected by Abbott on Aldabra, and breeding in thousands on small is lets  in 
the lagoon (Ridgway 1895, 527). Also collected on Aldabra by Voeltzkow 
(Berlepsch 1899, 496). Seen by Morr is  (1963), and hundreds seen in March 1964 
(Bourne 1966). Stated by Vesey-FitzGerald (1941, 528) to breed on Aldabra 
(and Cosmoledo), though no details a r e  given. Listed by Dupont (1907) f rom 
throughout the archipelago. 
Gygis alba monte Mathews Fai ry  Tern  
--- 
Collected by Abbott on Aldabra, where common (Ridgway, 1895, 527), and 
also collected there by Voeltzkow (Berlepsch 1899, 496). Seen by Morr is  
(1963), and hundreds seen in March 1964 (Bourne 1966). Listed by Dupont 
(1907) f rom Aldabra, Assumption and Astove. 
4 .  THE LAND BIRDS: THEIR STATUS, ORIGINS AND 
TRENDS O F  VARIATION 
Status 
Of the 16 species considered in Section 3(l)(a),  only one, the drongo 
Dicrurus aldabranus, is considered to be a full species, endemic to Aldabra. 
The following a r e  well marked subspecies, also endemic: Threskiornis 
aethiopica abbotti (the species is only otherwise known in the Malagasy 
Region from Madagascar); Dryolimnas e i  aldabranus (the species is 
known also from Madagascar, Mauritius, and the remainder of the Aldabra 
archipelago, but only still survives on Madagascar and on Aldabra); - Capri- 
mulgus madagascariensis aldabrensis (the species is only otherwise known 
from Madagascar); and Foudia eminentissima aldabrana (the species is only 
otherwise known from Madagascar and the Comoros). 
Other well-marked subspecies are: Butorides striatus crawfordi (known 
also from Assumption); Streptopelia picturata coppingeri (known also from 
Assumption and Gloriosa, the Aldabra birds being smaller); and Nectarinia 
sovimanga aldabrensis (admittedly there is a rather similar  subspecies, 
N. s. abbotti, on Assumption, but these two a r e  distinct enough from any other 
-- -
subspecies, including - N. - s. buchenorum, of Cosmoledo). Butorides S- has 
an almost cosmopolitan distrihution, Streptopelia picturata is widespread in the 
Malagasy Region, while Nectarinia sovimanga occurs also in Madagascar and 
on Gloriosa. 
Two further subspecies endemic to Aldabra, but only certainly distinguished 
by their smaller size, a r e  Falco newtoni aldabranus and Alectroenas sganzini 
minor. The former occurs also in Madagascar, the latter in the Comoros. Yet 
-
other, poorly marked, endemics are: Centropus S u  insularis (differing 
from 5. t. -- toulou of Madagascar only by i ts  longer tail and average longer 
wing-length, with C. - - t. assumptionis intermediate); Hypsipetes madagascar- 
iensis rostratus (differing from the populations of Madagascar, the Comoros 
-
and Gloriosa by a rather slight color-difference); and Zosterops maderaspa- 
tana aldabrensis (showing minor differences in colour and proportions from 
--- 
Z. m. maderaspatana of Madagascar and Gloriosa, and perhaps also Cosmoledo 
- - 
and Astove). 
Egretta garzetta assumptionis has been separated on material from Aldabra 
and Assumption a s  having a longer bill than bas E. g. dimorpha of Madagascar, 
-- 
but is not worth formal recognition. Finally, there a r e  two species the Aldabra 
populations of which a r e  indistinguishable. Ardea c. cinerea occurs in Europe, 
Asia, Africa, the Comoros, the Aldabra archipelago and the Amirantes, with 
A. c. firasa in Madagascar, while the populations of Tyto alba affinis inhabiting 
-
Madagascar, the Comoros and Aldabra differ from those of Africa merely by 
average larger size. Nor is there any evidence that any of the species whose 
status is uncertain (Section 3(l)(c)) show any peculiarity. 
The status of the land birds proved to breed on Aldabra presents an inter- 
esting range, from one "good" endemic species and several well-marked 
endemic subspecies down to two in which no variation at all can be discerned. 
Origins 
In the Comoros, Benson (1960b) found the land avifauna to be mainly of 
Madagascar origin, though with some African elements. The Madagascar in- 
fluence is proportionately even more preponderant on Aldabra, still more 
remote from Africa. The only claim to any African affinity ar ises  in the case 
of Ardea c. cinerea, in any event not a land bird in the str ict  sense that most 
of the other 15 species in Section 3( l ) (a )  are.  The only other one not having a t  
least an ultimate Madagascar origin is Butorides s tr iatus crawfordi. Both this, 
and the populations of the Mascarene islands and of the Comoros, appear to be 
of Asiatic origin, those of Madagascar and the Seychelles of African. B. s. 
- - 
crawfordi is again not a land bird in the s t r ic t  sense, and an Asiatic derivation 
need not tax the imagination. 
The following species, fo r  none of which is there any definite record from 
the Comoros,l could have colonised Aldabra f rom Madagascar via Gloriosa 
and the islands to the eas t  in the Aldahra archipelago: Egretta garzetta, 
Threskiornis aethiopica, Falco newtoni, Dryolimnas cuvieri, Centropus toulou 
-- -9 
Caprimulgus madagascariensis, and Nectarinta sovimanga. This is all the 
more  likely in the case  of E. garzetta, D. cuvieri and N. sovimanga, recorded 
-- 
from throughout the archipela-le -- C. toulou is alsoknown for  Assumption. 
This route may a160 have been used by Streptopelia picturata and Zosterops 
maderaspatana, the populations of which on these intervening islands a r e  very 
similar  to those of Aldabra. 
Alectroenas sganzini is only otherwise known f rom the Comoros, where i t  
may have originated after an ear l ie r  colonisation by Alectroenas stock from 
Madagascar. z a l b a ,  -Hypsipetes madagascariensis and eminentissima, 
also only known in the Aldabra archipelago f rom Aldabra, but occurring 
throughout the Comoros, a r e  probably also of proximate Comoro (ultimate 
Madagascar) origin. 
The origin of Dicrurus aldabranus is more obscure, though i t  is presumably 
Madagascar-derived. Possibly i t  arr ived via Gloriosa and the other islands in 
the archipelago, where however the Dicruridae a r e  unrepresented. There is a 
different species on each of the Comoros except for  Moheli, where again the 
family is unrepresented. It may have been one of the earl iest  colonisers - i t  is 
considered to have attained specific rank - and possibly arr ived before the 
frontal feathers  of g. forficatus of Madagascar were as developed a s  they 
now are.  
Trends of Variation 
The most pronounced general trend in variation is towards small  size, a s  
shown by wing-length. Thus on Aldabra Butorides striatus, Alectroenas 
sganzini, and Streptopelia picturata a r e  all smal le r  than in the Comoros, a s  
is m o  newtoni than in Madagascar and likewise to some extent Zosterops 
maderaspatana. -- F. araea,  the representative of newtoni in the Seychelles, is 
st i l l  smaller  than is newtoni on Aldabra. Streptopelia picturata has become 
-
still  smal le r  in the Seychelles too, while Butorides s tr iatus is about the same 
s ize  there a s  on Aldabra. On the other hand; Alectroenas pulcherrima of the 
Seychelles is la rger  than A. sganzini on Aldahra, and almost a s  la rge  a s  that 
species is in the Comoros. With the exception of A. pulcherrima, these cases  
fall  into line quite well with Bergmann's Rule, theeffect  of which has probably 
been accentuated by isolation. But Caprimulgus madagascariensis, which might 
I Except for  one record of F. newtoni on Anjouan as a stray, 
also be expected to be smal ler  on Aldabra than in Madagascar, is larger .  It has 
already been suggested that i t  may show an incipient tendency to gigantism in 
isolation. The same may apply to Nectarinia dussumieri  in the Seychelles, 
considerably la rger  than N. sovimanga, from which i t  may have been derived 
- 
long ago. 
The striking reduction in wing-length in Dryolimnas cuvieri is not con- 
sidered to be a reflection of reduction in s ize  s o  much a s  in powers of flight, 
presumably the resul t  of a lack of any natural enemies. The havoc caused by 
introduced enemies has been mentioned. - D. - c. aldabranus is almost flightless, 
while p. c. abbotti of Assumption, now extinct, was well on the way to this 
stage. 
Compared to the Comoros, where (Benson 196Oa, 10) the annual rainfall 
probably nowhere averages much l e s s  than 1000 mm. (about 40 inches), and 
around Mount Karthala, Grand Comoro, exceeds 5000 mm. (about 125 inches), 
there is a distinct tendency to reduction of melanin, often resulting in an in- 
c r ease  of pallor. This is well shown by Streptopelia picturata and Foudia 
-
eminentissima. The pallor on the underside of Butorides s tr iatus and brownish 
tone in I-Iypsipetes madagascariensis may be due to the same cause. In com- 
parison with Madagascar, this may also apply to Zosterops maderaspatana, 
yellower above, and Caprimulgus madagascariensis, paler on the crown and 
scapulars. Nectarinia sovimanga, on Assumption and Cosmoledo a s  well a s  on 
Aldabra, shows a reduction of the olive and yellowish tones, brightest in Mada- 
gascar  excepting the ar id south-west. But it is puzzling to find an extension of 
black in males in the Aldabra archipelago. This  is most marked on Cosmoledo, 
where by contrast reduction of the olives and yellows is also most marked. In 
N. dussumieri  of the Seychelles these tones a r e  only slightly apparent in juve- 
- 
niles. But perhaps the best example of reduction of melanin is in the immature 
Dicrurus aldabranus, grey above and white below instead of wholly black ex- 
cept for  m e r e  fringes of white on the underside a s  in D. forficatus of Mada- 
gascar  and adsimilis of Africa. The almost wholly white feathering on the head 
of the young Threskiornis aethiopica abbotti may also be the effect of this 
influence. 
Finally, an increase in length of bill, a characteris t ic  of many island popula- 
tions ( see  for  example Grant 1965), is apparent to some extent in Dryolimnas 
cuvieri aldabranus. Yet in Nectarinia sovimanga i t  has shortened, the opposite 
to N. notata in the Comoros a s  compared to Madagascar (Benson 1960a, 92). 
Foudia eminentissima aldahrana has a relatively heavy bill, possibly in adap- 
tation to a seed ra ther  than an insect diet. 
5. THE LAND BIRDS: COMPOSITION OF SPECIES 
Table 9 shows the occurrence of the various species of land birds in the 
Aldahra archipelago, drawn up from Section 3(l)(a),  with the addition of 
Cisticola cherina, and from Section 3(l)(c) of Corvus albus. Cosmoledo and 
--
Astove have been much l e s s  studied than Aldabra and Assumption, especially 
Aldabra. Nevertheless the l is t  is probably reasonably complete. No record a t  
all of the f irst  two species in the table has been traced from Cosmoledo or 
Astove, though i t  is likely that they do both occur, and may well breed. Some 
idea of the areas  of the four islands can be obtained from Watson, Zusi and 
Storer (1963, 191). A s  might be expected from i ts  relatively large land area  
(60 square miles), Aldabra has easily the largest number of species. 
Moreau (1966, 345-357) considered the avifauna of the Comoros, but not that 
of Aldabra. A few comparisons between the Aldabra l is t  and that for Grand 
Comoro in Benson (1960a, 17). slightly the nearest of the four Comoros to 
Aldabra, a r e  worth while. Grand Comoro is of course fa r  larger and higher, 
having an area  of 380 square miles and rising to 7874 feet (for areas and alti- 
tudes of the four Comoros, see  Watson, Zusi and Storer, 1963, 201). Neverthe- 
less, Moheli, the smallest of the Comoros, area  84 square miles only and not 
rising higher than 2950 feet, is almost a s  rich in species a s  Grand Comoro 
(Benson 1960a, 17), having 34 as  against Grand Comoro's 35, and Aldabra's 16. 
Due no doubt to lack of development, Aldabra has none of the following four 
introduced species, occurring on Grand Comoro and fairly general in the 
Comoros a s  a whole: Numida meleagris, Agapornis cana, Acridotheres 
Table 9. List of land birds breeding in the Aldabra 
Archipelago 
'X' indicates that the species has been proved, o r  may be assumed, to  breed on the island in 
question. A bracketed 'X' indicates that breeding is Likely but cannot be assumed. 
Ardea cinerea 
Butorides striatus 
Egretta garzetta 
Threskiornis aethiopica 
Falco newtoni 
Dryolimnas cuvieri* 
Alectroenas sganzini 
Streptopelia picturata 
Centropus toulou 
Tyto alha 
Caprimulgus madagascariensis 
Hypsipetes madagascariensis 
Cisticola cherina 
Dicrurus aldahranus 
Corvus albus 
Nectarinia sovimanga 
Zosterops maderaspatana 
Foudia eminentissima 
Aldabra 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
Assumption Cosmoledo Astove 
'Extinct except on Aldabra. 
tristis, o r  Passer  domesticus. Foudia madagascariensis may also owe i ts  
-
presence in the Comoros to an artificial introduction. Nor has it been estab- 
lished on Aldabra, and the nearest approach to a species associated with human 
activity is Corvus albus, which in any case is not certainly known to breed 
--
there, even though it does on Assumption. 
Nor has Aldabra any of the 10 African-derived species found on Grand 
Comoro, and mostly general in the Comoros, no doubt because it is more re- 
mote from Africa. Lack of suitable habitat might explain the absence of such 
Madagascar-derived species a s  Circus spilonotus and Saxicola torquata, asso- 
ciated with open grasslands (Cisticola -a, unknown in the Comoros, also 
associated with this type of habitat, occurs on Cosmoledo and Astove), or  
Coracopsis nigra, Chaetura grandidieri and Coracina c=a, associated with 
heavy forest (Corasopsis .- nigra is known also from Praslin, in the Seychelles). 
Yet Alectroenas sganzini and Foudia eminentissima, mainly forest dwellers 
-- 
in the Comoros, have both colonised Aldabra. Cypsiurus - parvus, occurring at 
lower altitudes throughout the Comoros, may have failed to colonise Aldabra 
because of a paucity of introduced coconut palms, providing suitable nesting 
sites. Two other species whose presence might be expected are  Alcedo vintsi- 
o&s and Terpsiphone *, both occurring throughout the Comoros. So f a r  
a s  the former is concerned, possibly there is a lack of suitable hanks for 
burrowing of nesting holes, while it may be noted that the genus Terpsiphone 
is represented in the Seychelles. 
Of the f i r s t  four species listed from Aldabra in Table 9, only Butorides 
striatus is on the Grand Comoro list. The absence of the other three (the 
-
Egretta and Threskiornis a r e  absent throughout the Comoros) may be due to 
a paucity o r  lack of suitable habitat, which may also explain the absence of 
Dryolimnas cuvieri (also absent throughout the Comoros). A s  already sug- 
gested in Section 3(l)(a), Falco newtoni, Centropus toulou and Caprimulgus 
--
madagascariensis, all present on Aldabra hut completely unknown in the 
Comoros (except f o r  one record of the f irst  named) may have failed to colonise 
the latter because originally they were too heavily forested. 
6 .  SUMMARY 
1. The history of ornithological exploration of Aldabra is outlined. 
2. So f a r  as  is possible from existing knowledge, the status of every species 
of bird known on Aldabra is assessed in a systematic list, divided into two 
categories, land birds and sea birds. 
3. Special attention is paid to the 16 known resident land birds, derived almost 
entirely ultimately from Madagascar, either via Gloriosa and the islands 
immediately to the south-east of Aldabra (Astove, Cosmoledo and Assump- 
tion) o r  via the Comoros. 
4. One form, a drongo Dicrurus aldahranus, is considered to have attained 
specific rank, and there a r e  a number of well-marked subspecies. In only 
two cases is there no apparent variation at all. Trends of variation include 
a strong tendency to small size in several species in comparison with Mada- 
gascar and/or the Comoros. On the other hand, a nightjar Caprimulgus 
madagascariensis has become somewhat larger than in Madagascar. The 
other most marked tendency is a reduction of melanin, often resulting in an 
increase in pallor, and perhaps associated with a relatively dry  climate. 
5. A special case  is that of a ra i l  Dryolimnas cuvieri,  which has become almost 
f:ightless, probably due to a lack of natural enemies. But due to the intro- 
duction of predators, i t s  continued existence is precarious, and it is already 
extinct on Assumption, Cosmoledo and Astove. 
6. The numbers of land birds on Aldabra, Assumption, Cosmoledo and Astove 
a r e  listed in a table. Aldabra, the largest in area,  has easily the highest 
number. The Aldabra l i s t  is compared with one f rom Grand Comoro. It 
lacks all  of the African-derived species on Grand Comoro, nor has i t  any 
introduced species. But there a r e  two herons and an ibis not on the Grand 
Comoro list ,  and a falcon, concal and nightjar unknown in the Comoros 
generally, perhaps originally too heavily forested for  their occurrence. 
7. Various palaearctic migrants, mostly shore birds, have been recorded from 
Aldabra. Two species have also been recorded as visitors from Madagas- 
car ,  and which also visit  Africa. Other species in both these categories 
which may also occur are listed. 
8. Among land birds of uncertain status, there is a flamingo, Phoenicopterus 
ruber. It appears not to be a distinct subspecies, and i t  is st i l l  uncertain 
whether i t  ever  breeds on Aldabra. It is possible that there is a breeding 
colony of the Crab  Plover Dromas ardeola. The nearest definitely known 
colony is in Somaliland. 
9. Aldabra is important a s  a breeding area  fo r  various s e a  birds, including 
very large numbers of two frigatebirds, Fregata minor and e, a booby 
Suia sula, and noddy Anous stolidus. 
--
7. REFERENCES 
An asterisk * indicates a work devoted entirely, o r  containing special reference, to Aldabra. 
Alexander, W. B. 1955. Bi rds  of the ocean. London. 
Bendire, C. 1894. Description of nests and eggs of some new birds, collected 
on the island of Aldabra, north-west of Madagascar, by D r  W. L Abhott. 
Proc. U.S. Nat. Mus. 17, 39-41. 
Benson, C. W. 1948. Notes f rom a sea  voyage: December 1946 - January 1947. 
Ostrich, 19, 150-151. 
Benson, C. W. 1953. A check l is t  of the hirds of Nyasaland. Blantyre and 
Lusaka. 
Benson, C. W. 1960a. The hirds of the Comoro Islands. Ibis, 103h. 5-106. 
Benson, C. W. 1960b. Les origines de l'avifaune de 1'Archipel des Comores. 
M6m. Inst. scient. Madagascar, S6r. A, 14, 173-204. 
*Benson, C. W. 1963a. Notes on some specimens mainly from Aldabra. Bull. 
Brit. Ornithol. Club, 83, 13-15. 
Benson, C. W. 1963h. The breeding seasons of birds in the Rhodesias and 
Nyasaland. Proc. 13th Internat. Ornithol. Cong., 623-639. 
Benson, C. W. 1964. Some intra-African migratory birds. Pukn, Occas. 
Papers  Dept. Game and Fish. N. Rhodesia, 2, 53-66. 
Benson, C. W. and Roux, F. 1967. Deux records m6connus des  Seychelles. 
Oiseau, 37, in press. 
*Berlepsch, H. von. 1899. Systematisches Verzeichnis de r  von Dr Alfred 
Voeltzkow in Ost-Afrika und auf Aldabra (Indischer Ocean) gesammelten 
Vogelbalge. 11. Vogel von de r  Insel Aldabra. Ahband. Senckenb. naturf. 
Gesellsch. 21, 489-496. 
Berlioz, J. 1946. Faune de 1'Empire francais. 4. Oiseaux de la ~ 6 u n i o n  
Paris .  
Berlioz, J. 1949. L'albinisme du plumage chez les ~ r d & i d & s .  Oiseau, 19. 
11-30. 
Betts, F. N. 1940. The birds of the Seychelles. 11. The s e a  b i rds  - more 
particularly those of Aride Island. Ibis, se r .  14, 4, 489-504. 
Blackman, R. 1965. Bristol University Seychelles Expedition. 7. Biological 
control. Animals, 7(3), 72-76. 
*Boulton, F. R. P. 1960. Bird notes of a visit  to  islands in the Seychelles and 
adjacent groups north of Madagascar. Sea Swallow, 13, 48-50. 
*Bourne, W. R. P. 1966. Observations on islands in the Indian Ocean. Sea 
Swallow, 18, 40-43. 
Brown, H. D. 1957. The breeding of the Lesse r  Flamingo in Mweru Wantipa, 
Northern Rhodesia. Ibis, 99, 688-692. 
Coppinger, R. W. 1883. Cruise of the "Alert". Four years  in Patagonian, 
Polynesian, and Mascarene waters (1878-82). London. 
(Coppinger, R. W. and others.) 1884. Report on the zoological collections 
made in the Indo Pacific Ocean during the voyage of H.M.S. 'Alert' 1881- 
2. London: British Museum (Natural History). 
*Dawson, P. 1966a. A survey of the sea  birds of the Seychelles Islands. 001. 
Rec. 40, 1-11. 
Dawson, P. 1966b. The validity of Bubulcus ibis  seychellarum. 001. Rec. 40, 
35-36. 
Dowsett, R. J. 1965. The occurrence of the Yellow Wagtail Motacilla flava 
-- -
flavissima in central  Africa. Ostrich, 36, 32-33. 
*Dupont, R. 1907. Report on a visit of investigation to St P ier re ,  Astove, 
Cosmoledo, Assumption and the Aldabra Group of the Seychelles Islands. 
Mahi?, Seychelles. 
*Fryer ,  J. C. F. 1911. The structure and formation of Aldabra and neighbour- 
ing islands - with notes on their f lora  and fauna. Trans. Linn. Soc. 
London, Ser .  2, Zool. 14 (Percy Sladen Expedition Reports, 3), 397-442. 
*Gaymer, R. 1966. Aldabra - the case  fo r  conserving this cora l  atoll, Oryx, 
8(6), 348-352. 
Grant, C. H. B. and Mackworth-Praed, C. W. 1933. On the relationship, status 
and range of Egretta garzetta, Demigretta gularis, D. schistacea, D. asha, 
-- 
and D. dimorpha, a new subspecies, and the cor rec t  type-locality of Egretta 
gar%tta. Bull. Brit. Ornithol. Club, 53, 189-196. 
-
Grant, P. R. 1965. The adaptive significance of some s ize  trends in island 
birds. Evolution, 19, 355-367. 
Griveaud, P. 1960. Une mission de recherche de 1'I.R.S.M. au Lac Ihotry. 
Nat. malgache, 12, 33-41. 
*Giinther, A. 1879. On the occurrence of a land rail (Rallus) in the island of 
-
Aldabra. Ann. Mag. Nat. Hist. Ser. 5, 3, 164-168. 
Hartert, E. 1925. Types of birds in the Tring Museum. Nov. Zool. 32, 
259-276. 
Irwin, M. P. Stuart and Benson, C. W. 1966. Notes on the birds of Zambia: 
2. Arnoldia (Rhodesia), (37) 2, 21pp. 
Loustau-Lalanne, P. 1962. Land birds of the granitic islands of the 
Seychelles. Seychelles Soc. Occas. Pub. 1. 
Lowe, P. R. 1924. Some notes on the Fregatidae. Nov. Zool. 31, 299-313. 
McLachlan, G. R. and Liversidge, R. 1957. Roberts' Birds of South Africa. 
Cape Town. 
Milon, P. 1959. Observations biologiques s u r  Egretta garetta dirnorpha 'a 
--
Madagascar. Ostrich, Suppl. 3, 250-259. 
Moreau, R. E. 1957. Variation in the western Zosteropidae (Aves). Bull. Brit. 
Mus. (Nat. Hist.), Zool., 4(7), 309-433. 
Moreau, R. E. 1960. The Ploceine weavers of the Indian Ocean islands. 
Journ. f.  Ornithol. 101, 29-49. 
Moreau, R. E. 1964. Article 'Malagasy Region' in Thornson, A. L. (editor), 
New Dictionary of Birds. London and New York. 
Moreau, R. E. 1966. The bird faunas of Africa. and i t s  islands. New York 
and London. 
*Morris,  R. 0. 1963. The birds of some islands in the Indian Ocean. Sea 
Swallow, 16, 68-76. 
Newton, E. 1863. Notes of a second visit to Madagascar. Ibis, 5, 333-350, 
450-461. 
Newton, E. 1867. On the land-birds of the Seychelles archipelago. Ibis, Ser. 
2, 3, 335-360. 
*Nicoll, M. J. 1906. On the b i rds  collected and observed during the voyage of 
the 'Valhalla', R.Y.S., f rom November 1905 to May 1906. Ibis, Ser. 8, 6, 
666712.  
*Nicoll, M. J.  1908. Three  voyages of a naturalist, being an account of many 
little-known islands in three oceans visited by the 'ValhallatR.Y.S. London. 
*Penny, M. 1965. Bristol University Seychelles Expedition. 5. The birds of 
Aldabra. Animals, 7(15), 409-411. 
Rand, A.  L. 1936. The distribution and habits of Madagascar birds. Bull. 
Amer. Mus. nat. Hist. 72, 143-499. 
Rand, A. L. 1960. Family Pycnonotidae, in Mayr. E. and Greenway, J.C. 
(editors), Check-list of b i rds  of the world, 9. Camhridge, Massachusetts. 
Reichenow, A, 1900. Die Vogel Afrikas, I, Neudamm. 
*Ridgway, R. 1893. Descriptions of some new birds collected on the islands 
of Aldabra and Assumption, northwest of Madagascar. Proc. U.S. Nat. 
Mus. 16, 597-600. 
*Ridgway, R. 1894a. Note on Rougetius aldabranus. Auk, 11, 74. 
*Ridgway, R. 189433. Descriptions of some new birds from Aldabra, Assump- 
tion and Gloriosa Islands, collected by Dr W. L. Abbott. Proc. U.S. Nat. 
Mus. 17, 371-373. 
*Ridgway, R. 1895. On birds collected by D r  W. L. Abbott in the Seychelles, 
Amirantes, Gloriosa, Assumption, Aldabra, and adjacent islands, with 
notes on habits, etc., by the collector. Proc. U.S. Nat. Mus. 18, 509-546. 
Ridley, M. W. and Percy, R. 1958. The exploitation of sea  birds in the 
Seychelles. Colonial Res. Studies, 25. London. 
Rountree, R. R. G., ~ u g r i n ,  R., Pelte, S., and Vinson, J. 1952. Catalogue of 
the birds of Mauritius. Mauritius Inst. Bull. 3(3), 155-217. 
Rudebeck, G. 1963. Aves 111. South African Animal Life, 9, 418-516. 
*%later, P. L. 1871. Description of a new species of dove from the coral- 
reef of Aldabra. Proc. 2001. Soc. London, 1871, 692-693. 
*Stoddart, D. R. and Wright, C. A. 1967a. Ecology of Aldabra atoll. Nature, 
213, 1174-1177. 
*Stoddart, D. R. and Wright, C. A. 196713. Geography and land ecology of 
Aldabra Atoll, Southwest Indian Ocean. Atoll Res. Bull. 118. 
Vaurie, C. 1949. A revision of the bird family Dicruridae. Bull. Amer. Mus. 
nat. Hist. 93(4), 199-342. 
Vaurie, C. 1959. The hirds of the palaearctic fauna. Passeriformes.  London. 
*Vesey-FitzGerald, D. 1940. The birds of the Seychelles. I. The endemic 
birds. Ibis, se r .  14. 4, 480-489. 
*vesey-FitzGerald, D. 1941. Further  contributions to the ornithology of the 
Seychelles Islands. Ibis, ser. 14, 5, 518-531. 
*Voeltzkow, A. 1897. Einleitung: Madagaskar, Juan de Nova, Aldahra. 
Abhand. Senckenb. naturf. Gesellsch. 21, 1-76. 
*Voeltzkow, A. 1917. Reise in Ostafrika. Wissensch. Ergebn. 3. Stuttgart. 
*Watson, G. E., Zusi, R. L. and Storer,  R. E. 1963. Preliminary field guide 
to the birds of the Indian Ocean. Washington. 
White, C. M. N. 1951. Systematic notes on African birds. Ibis, 93, 460-465. 
White, C. M. N. 1965. A revised check-list of African non-passerine birds. 
Lusaka. 
Williams, J. G. 1953a. Revision of Cinnyris sovimanga: with description of 
a new race. Ibis, 95, 501-504. 
Williams, J. G. 1953b. On the s tatus of the Seychelles sunbirds Cyanomitra 
dussumieri and Cyanomitra mahei. Ibis, 95, 545-546. 
Witherby, H. F., Jourdain, F.  C. R., Ticehurst, N. F., and Tucker, B. W. 1941. 
The handbook of British birds, 3. London. 
Worth, C. Brooke. 1960. Notes on sea birds in harbours of Portuguese East 
Africa. Ostrich, 31, 173-174. 
Chapter 5 
OBSERVATIONS ON THE BIRDS OF ALDABRA IN 1964 AND 1965 
R. Gaymer 
Department of Zoology, Bristol University 
1. General Observations 
2. The Land Birds 
3. Notes on Sea and Shore Birds 
4. Acknowledgments 
5. References 
Atoll Research Bulletin No. 118: pp. 113-125 November 15, 1967 
1. GENERAL OBSERVATIONS 
Birds a r e  conspicuous on Aldabra, for  although the number of species is 
small,  the species themselves a r e  represented by la rge  populations. This paper 
presents observations on the natural history of the land birds, together with 
some notes on the sea  and shore birds, obtained during two visits to Aldabra 
made by the Bristol Seychelles Expedition, the f i r s t  f rom 11 November to 14 
December 1964, the second from 4 October to 20 November 1965. 
Fourteen land birds a r e  considered here, together with the flamingo, which 
spends much of i t s  t ime at inland pools. Of these fourteen, only three have ap- 
parently not diverged from their Madagascan o r  Comoran ancestors (Benson 
1967). These a r e  the Pied Crow Corvus albus, which is extremely mobile 
amongst these islands; the Cattle Egret Bubulcus which seems to be a 
recent arr ival ;  and the Madagascar Bulbul Hypsipetes madagascariensis. Pied 
Crows a r e  frequent around the settlement on West Island, and also occur in 
a r eas  of Mixed Woodland and beach vegetation on South Island. Their total num- 
be r s  cannot exceed a few hundreds. Cattle egrets  have previously been recorded 
only a s  r a r e  vagrants, but as elsewhere there has been a recent increase, and 
a t  least 100 birds now live on South Island, around Takamaka. 
There a r e  no introduced birds on Aldabra apart  from the few chickens on 
West Island, despite the many introduced species in neighbouring island groups. 
Very large numbers of migrants visit Aldabra, but these a r e  mainly waders, 
which feed on the lagoon and among the brackish pools in the southeast. A num- 
ber  of vagrant land birds have also been recorded, and a r e  listed by Benson 
(1967). Only the Broad-billed Roller Eurystomus glaucurus glaucurus may 
occur regularly, having strayed on migration between Africa and i ts  breeding 
quarters  in Madagascar. The Blue-cheeked Bee-eater Merops superciliosus 
might be expected, since it has been seen on Cosmoledo (R. Gaymer, October l), 
a s  might the Madagascar Grass-warbler Cisticola cherina, which is common on 
Cosmoledo and Astove. Four specimens of a barn owl were  collected on Alda- 
bra in 1892 and one in 1906, but none have been recorded since, and they must 
be assumed extinct. They do not appear to differ f rom the African Tyto alba 
affinis (Benson 1963), which also occurs in Madagascar and the Comoros. 
The main land bird habitats a r e  (1) mixed scrub  and woodland covering the 
interior of South Island, and to a l e s s e r  extent West and Middle Islands; 
(2) Pemphis scrub, which covers most of the r e s t  of the atoll; (3) mangrove 
communities fringing the lagoon; and (4) the coastal vegetation, which is best 
developed in the west. 
In probable o rde r  of abundance the commonest species a r e  the Sunhird, the 
Fody, the Bulbul and the White-eye. These a r e  omnivorous birds, able to 
utilise the many flowering shrubs and trees,  with which their breeding season 
is synchronised. Excepting the pigeons, the la rger  birds a r e  either scavengers 
with a wide range of foods and feeding sites, such a s  the Ibis and Pied Crow, 
o r ,  l ike the Kestrel,  Nightjar, Drongo and Coucal, they a r e  more specialised 
and feed on l izards o r  large insects which a r e  in more  regular hut limited sup- 
ply. These birds a r e  mostly less  numerous, despite their  smaller  size. 
The fruits and seeds of the flowering plants provide a large and continuous 
food supply for  the ground-feeding Turtledove, s ince germination and decay a r e  
minimal on the dry rocky o r  sandy ground. Fleshy fruits a r e  much less abundant, 
and the supply must be very seasonal. This probably explains the rather small 
numbers of the Comoro Blue Pigeon, which a r e  only common in the southeast, 
where Ficus and other trees a r e  concentrated. The numbers and distribution of 
the other birds also correspond with the vegetation types. 
1. Mixed Scrub on Platin 
Most of the land birds a r e  commonest here, with the exceptions of the Pied 
Crow and the White-throated Rail, which latter is confined to the mangrove, 
Pemphis scrub and beaches of Middle Island and Polymnie. The Comoro Blue 
Pigeon, Madagascar Coucal, Madagascar White-eye, and probably the Madagas- 
c a r  Nightjar a r e  only otherwise found in areas  of rich beach vegetation. The 
White-eye and the Coucal seem particularly dependent on dense cover. Although 
found inland, the Pied Crow is best considered a s  a littoral scavenger, and is 
commonest around the outer coast. Cattle Egrets roost in a large clum of t rees  
at Takamaka. as  do the Sacred Ibis and fruit bats. 
2. Pemphis Thicket on Champignon 
Pemphis appears to provide little food, and i t  is generally avoided by the 
birds. The White-throated Rail is an exception. Where mixed woodland is close, 
the Sunbird and the White-eye a r e  sometimes seen, and the former a t  least may 
nest. 
3 .  Mangrove 
Mangroves a r e  a major habitat for  nesting sea birds, and dense stands of 
Rhizophora a r e  also inhabited by occasional water birds, and by Drongos, which 
nest near the edges. Small numbers of Sunbirds occur in open mangrove of this 
type, and also of Avicennia and other genera, a s  do Drongos and sometimes 
Kestrels and Fodies. Sacred Ibis feed in mangrove on the lagoon margins. 
Turtledoves may nest in mangrove, but this has nor been observed. The Fla- 
mingos a r e  largely confined to this habitat, which also serves a s  winter quar- 
ters  for many migrant waders. 
4. The Settlement 
The settlement area on West Island is visited by Sunbirds, Bulbuls and 
White-eyes, but only because it is an area  of rich beach vegetation. The Fody 
and Turtledove exploit the food provided by the kitchens and the feeding of 
domestic animals, the Fody being especially efficient in competition with 
chickens for rice. Both species also exploit the many Casuarina trees along 
the beach, and the Fody breeds in the lower branches. Pied Crows scavenge for 
offal when possible, but a r e  discouraged. The other birds avoid the settlement. 
2.  THE LAND BIRDS 
Threskiornis aethiopica abbotti Ridgway Sacred Ibis 
Because of its large s ize  (70 cm.) and pleasant flesh, this bird is uncom- 
mon and is restricted to the more remote parts of South Island, where it is most 
abundant in well-developed mixed woodland and open mangrove. It feeds in 
small groups in the lagoon at low tide, o r  in twos and threes inland (Plate 28). 
Large numbers roost at Takamaka, where a colony was found nesting over a 
small tree by the pool (Plate 33). There were 21 nests, built in a mass at, a 
height of 7-10 feet; 17 of the nests contained two eggs, two had one egg, and 
one had three. The eggs were off-white in colour, stained, and without lustre. 
By the following day (November 22) a further bird had laid. Over the next five 
days all the eggs vanished, despite minimal disturbance. Fryer  (1911) found a 
similar colony in which two out of a total of 18 eggs were destroyed, accord- 
ing to him in gaining access to their own individual nests. The nests found in 
1964 were ahout 45 cm. in diameter, composed of twigs, and lined with a small 
amout of tufts of grass and dead and fresh leaves, none of which were woven. 
The cavities were shallow. Nico11 (1906) found old nests in mid-March, a t  
which time the young were fully grown. 
Reports of feeding include the taking of scraps and turtle offal from around 
the camps of turtle fishermen, and small crabs and other marine animals. The 
bill is used to probe for  food in the mud of the lagoon and of fresh and brackish 
pools inland. Many Ibis a r e  also seen searching in leaf l i t ter  inland, and may eat 
lizards, large insects, and some vegetable matter. These birds were once ex- 
tremely tame, hut although all ages a r e  still very inquisitive, only the juveniles 
now approach to within two o r  three yards: they a r e  recognisable by their rather 
shabby appearance, smaller  size, and feathered necks. 
Phoenicopterus ruber roseus Pallas Greater Flamingo 
--
The flamingos on Aldabra have been variously reported "resident. . . 
numbers 500 to 1000" o r  absent, and therefore previously only a s  migrants in  
passage. It is clear that they a r e  regularly present at least in the southeast, 
where they occur in  small groups o r  pairs in the brackish pools amongst the 
mangroves (Plate 36). There seemed to he about 50 birds a t  the time of our 
visit, but they a r e  very shy and difficult to approach. They may breed, but this 
has not been confirmed. Although the mangroves in the southeast seem to be 
the main habitat, flamingos have also been reported in the lagoon proper; flying 
over Middle Island in  the east; and over South Island near Dune Jean Louis. 
Falco newtoni aldahranus Grote Madagascar Kestrel 
--
This kestrel hunts lizards and rarely hovers, but is otherwise fairly typi- 
cal. The male is chestnut and black dorsally, with a grey head, and spotted 
beneath. The female is larger, more spotted, and generally brownish above. 
The only prey seems to he the lizards Ablepharus and Phelsuma, and possibly 
some nocturnal geckos. Unlike the Madagascan form, this bird avoids human 
habitations. It occurs over much of South Island, but since breeding terri tories 
a r e  very large, the total population cannot exceed 100 birds. The only breeding 
record is one nest at Anse Mais, on the west coast of South Island. It was found 
on 18 November, in the crown of a coconut palm, a t  about 25 feet above the 
ground, and contained a lit t le down and three la rge  young (see Penny 1964, 40). 
Lizards were being brought to the young by the parents, who also defended the 
a rea  against Pied Crows, Drongos and Bulbuls. On one occasion a kestrel  was 
observed driving seven Pied Crows away. This behaviour was seen a t  Takamaka, 
indicating that breeding may also have been in progress there. 
Dryolimnas cuvieri aldabranus (Giinther) White-throated Rail 
This Rail, the Aldabra fo rm of which is flightless, has head, neck and breast 
a dull chestnut colour, otherwise the general colour is olive, with the chin and 
throat of adults white. It appears  to be confined to Middle and Polymnie islands, 
but may also occur on Espri t  and Michel in the lagoon. There is no evidence 
that ra i l s  have lived on South Island, although Abbott (in Ridgway 1895) s ta tes  
that they did and had been exterminated by f e ra l  cats. Rails were  then common 
around the settlement on West Island, but were r a r e  by 1908 (F rye r  1911) and 
have not been recorded since. Cats and r a t s  a r e  the most likely cause of their  
extinction on West Island. 
It is possible that these Rails a r e  in some way associated with the large 
colonies of s e a  birds which occur in the same areas. Eggs a r e  certainly eaten 
with speed and efficiency when offered, although la rge  insects and shore crabs  
may be more important foods in the wild. 
Bendire (1894) describes the only nests recorded, collected by Abbott. They 
were rather  loosely constructed f rom sma l l  twigs and plant s tems,  one a t  18 
inches above the ground, the other more  typically in a cavity in the rock. The 
f i r s t  nest was 25 cm. wide and 18 cm. deep, with a cavity measuring 11.5 by 9.5 
cm., which meant that the hen sat  withonly the head protruding. The second nest 
was composed of finer materials,  mainly dried grass,  and was concealed behind 
a tuft of grass.  Clutches were 4, 3, 2 and 2. The average s ize  of the eggs was 
4.25 x 3.0 cms. The shells were strong, fair ly glossy with fine granulations, 
and of a creamy white colour, sparingly dotted with l iver  brown, vineaceous and 
lavender. The marks were heaviest a t  the la rger  end. These nests were taken 
in December, so i t  i s  surpris ing that others  on Aldabra at the time have seen no 
signs of breeding. Abbott (1893) says that a few pairs  were breeding in Septem- 
ber, but that most did not breed until November-December. Nicoll (1906), who 
was on Assumption from 11 to 13 March, thought the breeding season of the 
Rail was over, though he did see  severa l  young still  covered with black down. 
On Aldabra, Abbott gives the clutch s ize  a s  three, ra re ly  four, despite local 
reports  that this i s  often exceeded. The hen s i t s  very closely and quickly re-  
turns once disturbed. In Madagascar the breeding season of this species prob- 
ably includes October, November, and January to March (Rand 1936). 
A startling variety of calls is produced, with the head raised. A drum-like 
sound, often followed by a long curlew-like whistle, is common, and when ex- 
cited a se r i e s  of shrieks and grunts can be produced, which may be used to cal l  
the young (Nicoll 1906). Pa i r s  a r e  terr i torial  and fighting has been reported. 
Alectroenas sganzini minor Berlepsch Comoro Blue Pigeon 
This medium-sized frui t  pigeon is strikingly coloured pale grey and mid- 
night blue, with bare  r ed  skin around the eye (Gaymer 1966; Penny 1965, 411). 
The male has some of the feathers  on the head and neck faintly tipped with 
pink. Juveniles a r e  green with some  yellow above, and greenish grey below. 
Small groups of blue pigeons a r e  conspicuous in la rger  t rees,  and they a r e  
also seen flying overhead a t  some  height in ones and twos. They a r e  well dis- 
tributed in the mixed woodland on South Island and West Island, often revealing 
their  presence by a hoarse 'hoo', repeated four o r  five times. This is especially 
characteris t ic  of the male display, in which he hops through the canopy of a t r ee  
af ter  a female, cooing, bowing, and rais ing the plume feathers of the head and 
neck, often stopping to drive away other birds, including Bulbuls. This display 
has been regularly observed in November and December, but the testes of two 
males taken a t  that t ime were sma l l  (10 x 4 mm.) with little fat. Nesting and 
rear ing  may occur in February to March. Young birds have been seen with their 
parents in March (Nicoll 1906). In the Comoros Benson (1960) collected a fe- 
male of this species containing a n  almost fully developed egg on 2 November, 
while in Madagascar Rand (1936) found that A. madagascariensis breeds f rom 
July to March. On Aldabra the nests  a r e  pro?;ahly built in the tops of la rger  
t r ee s  inland. 
These pigeons eat  the fleshy fruits of Ficus sp. (la fouche, banyan) and 
sma l l  flocks a r e  attracted to these and other fruiting trees. Fru i t s  up to 1 cm. 
in diameter a r e  swallowed whole, many being dropped while feeding. Drinking 
has not been observed, nor have they been seen on the ground. 
Streptopelia picturata coppingeri (Sharpe) Madagascar Turtledove 
This pinkish grey-brown dove, about 30 cm. in length, spends much t ime on 
the ground in small  groups, searching fo r  seeds, which a r e  the main food. 
Casuarina seeds a r e  eaten where possible, and some r ice  and other scraps  
a r e  eaten a t  the settlement. In the Comoros some insects a r e  also taken (Ben- 
son 1960) but this has not been seen  on Aldabra. Small freshwater pools a r e  
visited regularly in the morning and evening (at least in the dry season), being 
approached on the ground, usually in sma l l  flocks. 
Remarkably little is known about breeding. Abhott (in Ridgway 1895) re-  
ports  that nesting occurs in mangrove in September to November. This is sur-  
prising, since they a r e  now rare ly  seen  in mangrove. Males were  observed 
courting and driving other males away during November and December. In the 
Comoros, Benson (1960) had evidence of this species breeding in August to 
November, while in Madagascar Rand (1936) found that the season probably 
extends a t  least from July to October. On Aldahra, two white eggs are prob- 
ably laid on a flimsy platform of twigs in the canopy of a t ree,  a s  elsewhere. 
Centropus toulou insularis Ridgway Madagascar Coucal 
A large clumsy bird, about 45 cm. long, which includes a long graduated 
tai l  and heavy hooked beak. Both male and female have the characteris t ic  
call--a descending "tou-lou-lous'--but a t  different pitches, the male's being 
the higher. This call carries very well, and often reveals their presence 
when the birds a r e  well hidden in the canopy of a t ree  o r  in a bush. They a r e  
only found in areas of dense mixed vegetation, in which much of their time 
is spent in search of food. This consists of centipedes, lizards, crickets, and 
probably grasshoppers, cicadas, mantids, etc. Bird eggs a r e  also eaten, and 
young may be taken too. Abbott (in Ridgway 1895) reports his belief that small  
r a t s  a r e  eaten. Food is swallowed whole, being captured mainly on the ground. 
Abbott describes the nest, which is oval and very large, with an entrance at 
one end, by which he presumably means at the side. It is made of loosely inter- 
woven str ips of bark, grass, and, where available, coconut leaves. He gives the 
height a s  5 to 8 feet above the ground, although Fryer (1911) describes a nest 
a s  "low down" in a bush. Three o r  four white eggs a r e  laid. The birds a r e  in 
breeding plumage by October, and pairs  can be heard calling together in their 
large territories. A s  in Madagascar (Rand 1936), the breeding season of this 
species probably extends from December to March. 
Caprimulgus madagascariensis aldabrensis Ridgway Madagascar Nightjar 
This nightjar is about 24 cm. long, with typical grey and brown cryptic 
coloration. It is rarely seen, but at night the falling rattle and two-noted cry 
(with the second note stressed) can commonly be heard inland, especially in 
the southeast. Abbott (in Ridgway 1895) also reports a "winnowing" cry. 
Occasionally a roosting bird may be flushed from the ground during the day. 
Almost nothing is known of this bird's habits. Abbott reports that beetles were 
taken a t  night from around a pile of refuse on West Island. He states that breed- 
ing occurs on open ground o r  sand hills, and found a nest with young in Septem- 
ber. Rand (1936) records breeding of this species in Madagascar in  August, 
September and October. 
Hypsipetes madagascariensis rostratus (Ridgway) Madagascar Bulbul 
This noisy bird is grey, with an orange bill and a short  black erectile 
crest. It is sometimes in groups of up to a dozen, although a group of two o r  
three is more normal. The song is a harsh, quite complex whistle, but many 
other sounds a r e  made. Berries and other fruits, flowers, and flower buds 
form the major part of the diet, but mantids, orthoptera and other large in- 
sects  are  taken when possible, sometimes on the wing. 
The breeding season probably extends from November to January, though 
in the Comoros Benson (1960) gives evidence of breeding starting a s  early a s  
September, and in Madagascar Rand (1936) gives the season as  extending at 
least from September to January. On Aldabra nesting material was being car-  
ried on 27 November, and two nests were collected by Abbott on 22 December 
and 31 December. These a r e  described by Bendire (1894). They were rather 
slight, and composed of fine rootlets, small  twigs, dry leaves and plant fibres, 
being lined with finer materials of the same kind, plus dry grasses. They 
measured 10.4 x 7.2 cm. externally, and 9.5 x 4.5 cm. deep internally. Both 
were at about 8 feet above the ground, in the crotches of thorny shrubs. One 
contained two eggs, the other only one, and these averaged 2.48 x 1.77 cm. The 
shells were close grained, glossy vinaceous pink, profusely spotted and blotched 
with different shades of claret brown, vinaceous rufous and lavender, forming 
a wreath at the larger end. 
Dicrurus aldabranus Ridgway Aldabra Drongo 
Adults of this species a r e  black, with a long forked tail and a total length of 
about 28 cm. The bill is stout and compressed, hooked at the tip, with strong 
nasal bristles a t  the base. Immature birds a r e  rather unevenly grey, paler 
beneath. Drongos a r e  commonly seen in pairs  o r  family parties, sitting con- 
spicuously on bare branches in mixed woodland near mangrove. It is a pug- 
nacious bird, with large territories. The nesting area itself is successfully 
defended against even Ibis and Grey Herons. Bendire (1894) describes two 
nests, collected in November and early Decemher. These were very firmly 
constructed of fine twigs and lined with finer ones, to form a rather shallow 
cup 7.5 cm. wide and 3.25 cm. deep, the outer dimensions being 14 x 5 cm. 
Three eggs were rich cream, with scattered spots of cinnamon rufous and 
brick red, some with one o r  two lavender dots. There was no lustre, and the 
markings were heavier at the larger end. Average measurements were 2.65 x 
1.9 cm. These nests were built on a horizontal branch of Casuarina, but where 
this tree is absent, nests a r e  built in mangrove, at a height of 15-20 feet above 
the ground. Inland, nests may be built in large Ficus and other trees. One such 
nest was composed mainly of dried sedges, looped over a fork at 18 feet. It was 
f ra i l  in  appearance, with a fairly deep cup internally. Spider's web is often in- 
corporated, and this was also noted by Abbott (in Ridgway 1895). Abbott gives 
the clutch size as  three o r  four. 
A nest with one young was seen at the end of November, but it was later  
found abandoned. Another nest was found on 2 Decemher containing three young. 
Several family parties were seen in November and December, but none had more 
than two young, and most had only one, and this may be the usual number 
reared. Benson (1960) found eggs of D. waldeni on Mayotte in the Comoros in 
-- 
October and November, while Rand (1936) found the breeding season of D. 
forficatus in Madagascar to be from September to December. Nothing i;known 
about feeding, but related species eat beetles, homoptera, and spiders. The 
young a r e  fed by both parents on what appeared to be large insects. 
Nectarinia sovimanga aldabrensis (Ridgway) Souimanga Sunbird 
This is a typical sunbird, very small  (about 11 cm.), with a long down- 
curved beak. The male has bright metallic coloration, the female and juve- 
niles a r e  dull brownish grey. These birds a r e  very active, and hop contin- 
uously through bushes and trees, uttering a frequent high-pitched 'chink'. 
The males sing loudly in the breeding season, which is prolonged, extending 
a t  least from September to January (Abbott in Ridgway 1895). Morris (1963) 
found eggs in January. Nests a r e  domed, and usually suspended from a branch 
a t  4-12 feet above the ground, o r  sometimes hung from branChes or roots 
over the edge of a pit in the ground. The nest i s  begun by fastening s t reamers  
of twice o r  more the final length of the nest to the chosen Pemphis, mangrove, 
o r  other branch. Abbott (in Ridgway 1895) describes the formation of an oval 
mass of nesting material, which the hen then opens out by pushing in her head 
and body, la te r  entering the cavity, and finally lining i t  with feathers. The nest 
includes bark fibres, grasses,  dried marine g ra s s  f rom the beach, down f rom 
pods of wild cotton, and many hundreds of feathers. It takes about eight days to 
build, all the work being done by the female. Vesey-FitzGerald (1940) gives the 
internal dimensions of a nest on Astove as 10 cm, deep and 8 cm. wide, the en- 
t rance being 3.5 x 4.0 cm. Morris  (1963) gives the entrance a s  4 cm. in a nest 
about 11.5 cm. across. He describes the eggs a s  dirty white, mottled with um- 
ber. He la te r  found this nest in "tattered ruins". Two nests which were built 
into a branch, ra ther  than suspended, were  also the highest seen, a t  10 and 12 
feet  above the ground. The nesting density is sometimes very high. Eleven nests 
were  counted a t  Anse Mais in mid-November. Two eggs a r e  laid, and incubation 
takes 13 days, the sexes sharing the task. The eyes of the young open on the 
seventh day. 
Nectar is sipped with the tubular tongue, sometimes while hovering, but 
generally while perched. Small flies a r e  eaten in large numbers, with some 
solid vegetable matter,  mainly stamens and other flower parts.  A l l  solid food 
is swallowed in very small  pieces. The young a r e  probably fed mainly on in- 
sects .  
Although no longer s o  tame that they alight on one's a r m  (Abbott in Ridgway 
1895), the females and juveniles will often inspect an intruder while hovering 
in front of his face. 
Zosterops maderaspatana aldabrensis Ridgway Madagascar White-eye 
This tiny yellow to olive-green bird, with a white ring around the eye, i s  
usually seen in small  flocks, which move through the bushes and t r ees  with 
repeated soft calls,  well described by Morr is  (1963) a s  a low, rather  bell-like 
'tee-eep", and an almost continuous low twittering. Although often hard to lo- 
cate, white-eyes a r e  very common in a r e a s  of r ich beach vegetation and in the 
denser  parts  of the mixed woodland. The diet is mixed, consisting of ber r ies  
(swallowed whole), small  beetles and other invertebrates, nectar taken up with 
the brush tongue, and buds and flower parts. Food is not taken on the wing. 
Breeding takes place from October to December (Abbott in Ridgway 1895). 
Nests a r e  built a t  about 6 feet above the ground, slung into a fork a t  the top of 
a bush. They form a smal l  deep cup, in which two o r  three pale blue-green 
translucent eggs a r e  laid, and a r e  composed of shreds  of bark, leaves, g ra s s  
and sma l l  twigs, with little lining. Casuarina needles have also been reported. 
During courtship pairs  can be seen preening each other around the head and 
neck while sitting side by side on a branch. The male sings, and pairs  a r e  te r r i -  
torial, but this is not s o  apparent a s  in most of the other birds. 
Foudia eminentissima aldabrana Ridgway Red-headed Fores t  Fody 
This bird is common and conspicuous, especially around the settlement on 
West Island. The female is somewhat sparrow like, but i s  more yellow, with 
dark streaks, and has a more powerful bill. The male in breeding plumage has 
a vivid orange-scarlet head and breast,  with the belly and back yellow and the 
rump orange. Immature birds resemble the female. 
Flocks of breeding adults may be formed while feeding, but this is unusual. 
Males are strongly territorial,  with a characteristic threat  display, in which 
the wings and tai l  a r e  drooped, and the head, breast and rump feathers puffed 
out (Plate 35). The intruder is then challenged with a s e r i e s  of wheezing o r  
fizzing calls, and a metallic 'ching-ching'. A female may be s o  challenged, but 
on recognition the cal ls  become a se r i e s  of thin high whistles a t  about half- 
second intervals, uttered by one o r  both sexes. The male then ra ises  his wings 
high and quivering above his back (in obvious strong contrast  with the threat 
posture) and if accepted mounts and copulates with the crouching female, keep- 
ing his wings raised. Copulating was observed in November and December. 
Terr i tor ies  may be a s  small  a s  1000 square yards in groves of la rger  t rees,  
indicating a possible forest  ancestry. Nests may be f rom 4 to 20 feet high, and 
if one is destroyed another is built nearby. Mixed woodland is preferred, and 
Casuarina is used if available. Nests in mangrove a r e  rare. Abbott (in Ridgway 
1895) gives the clutch a s  four, but those he collected were  3, 3, 2 and 2. We ob- 
served four nests with eggs: all  had three eggs, these being laid in one case  on 
consecutive days, ceasing after the third egg. Abbott also s ta tes  that nesting is 
in November, December and January; i t  probably extends to February o r  
March. The male a s s i s t s  in nest construction but not in incubation. Bendire 
(1894) describes the nest and eggs. Nests a r e  domed, and a r e  built into the 
branches of a t r ee  o r  shrub. They measure 23 x 18 cm., with inner dimensions 
7.5 cm. wide and 7.0 cm. deep. The eggs are pale glaucous green, nearer  blue, 
unspotted, with a ra ther  thin glossy shell. They average 2.05 x 1.4 cm. in size. 
These fodies feed on seeds, flowers and beetles taken from among bushes 
and t rees ,  o r  f rom the ground. Other small  invertebrates may also be taken. 
Rice and kitchen scraps  a r e  eaten a t  the settlement, and Casuarina seeds 
wherever found. Abbott repor ts  that unripe maize was eaten if opened by ra ts ,  
but since the bill is very powerful, they must have been s o  unfamiliar with 
maize that they attacked i t  only when exposed. 
3 .  NOTES ON SEA AND SWORE BIRDS 
There have been no studies of the marine birds of Aldabra, apart from a 
smal l  amount of collecting, and some  scattered observations. Benson (1967) has  
listed the known species. The following notes on sea  and sho re  birds a r e  divided 
into (1) known breeding species, and (2) unconfirmed breeding species. 
1. Breeding Species 
Phasthon rubricauda Red-tailed Tropicbird 
A population probably numbering some hundreds lives mainly along the 
northern part  of the lagoon, breeding on smal l  is lets  under rock ledges, bushes 
o r  tal l  g ra s s  (Plate  31). Nest with egg found on 18 November. 
Sula sula Red-footed Booby 
-- 
Many thousands breed in colonies scat tered amongst the frigate bird camps 
on Middle Island. Vesey-FirzGerald (1941) describes nesting, and states  that 

Sterna albifrons Little Tern 
Perhaps a hundred seen along the northern coast in November, and more 
rare ly  in the lagoon. They a r e  locally reported to breed, laying one egg in a 
sand scrape. 
Thalasseus bergii Crested Tern  
Frequently seen feeding in shallow water over the outer reef  o r  in the 
lagoon, sometimes in sma l l  groups. Locally reported to breed, young being 
taken f rom the hare  low Chalen Islands, near West Channels. 
Gygis alba Fairy Tern 
--
Seen flying in twos and threes  in the lagoon. Locally supposed to breed 
throughout much of the year. 
Drornas ardeola Crab Plover 
Flocks of up to severa l  hundred feed on exposed sand and mud over the reef 
in the west and in the lagoon. Not locally thought to breed. 
3.  Non-Breeding Migran ts ,  Vis i to rs  and  Vagrants  
The following species occur in large numbers in the creeks and pools of 
the mangrove around Bras Takamaka and elsewhere, and sometimes around the 
outer coast and in the lagoon a t  low tide: Turnstone Arenaria interpres, Whim- 
brel  Numenius phaeopus, Sanderling Crocethia alba. Less  common are the 
Greenshank Tringa nebularia, the Common Sandpiper Actitis hypoleucos, the 
Curlew Sandpiper m a  testacea, and the Wood Sandpiper Tringa glareola. 
The Turnstone is probably the only species present throughout the year. 
Other species of sea  birds reported include the Sooty Tern  Sterna fuscata, 
--
the Lesser  Black-backed Gull L a r u s  fuscus, and possibly the Blue-faced and 
--
Brown Boobies - Sula dactylatra melanops and - Sula leucogaster (F rye r  1911, and 
local reports). 
4. ACKNOWLEDGEMENTS 
I thank the other members of the Bristol Seychelles Expedition, who shared  
with me the work on which this paper is based, and also those who by their  
gif ts  and assistance made the expedition possible, and particularly the World 
Wildlife Fund f o r  their support. 
Dr W. R. P. Bourne and Mr C. W. Benson have read the manuscript and 
made suggestions. I would also like to express my appreciation of the invaluable 
Preliminary Field Guide to the Birds of the Indian Ocean by Watson, Zusi  and 
Storer (1963). 
5. REFERENCES 
Abbott, W. L. 1893. Notes on the natural history of Aldahra, Assumption and 
Glorioso Islands, Indian Ocean. Proc. U.S. Nat. Mus. 16, 759-764. 
Bendire, C. 1894. Description of nests  and eggs of some new birds, collected 
on the island of Aldahra, north-west of Madagascar, by Dr W. L. Abbott. 
Proc. U.S. Nat. Mus. 17, 39-41. 
Benson, C. W. 1960. The birds of the Comoro Islands. Ibis, 103b, 5-106. 
Benson, C. W. 1963. Notes on some specimens mainly f rom Aldabra. Bull. 
British Ornithol. Club, 83, 13-15. 
Benson, C. W. 1967. The hirds of Aldabra and their status. Atoll Research 
Bulletin 11 8. 
F rye r ,  J. C. F. 1911. The s t ruc ture  and formation of Aldabra and neighbour- 
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Gaymer, R. 1966. Aldabra--the case  fo r  conserving this coral  atoll. Oryx, 8, 
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Chapter 6 
BIBLIOGRAPHY O F  ALDABRA 
D. R. Stoddart 
Department of Geography, Cambridge University 
This Bihliography of Aldabra must be incomplete, since systematic search- 
ing of the l i terature has yet to be made fo r  Aldabra references in many fields, 
particularly in history. It concentrates on recent scientific literature, but 
again, though a fair ly intensive search  has been made, many items must have 
been missed. It is likely, however, that no important item pertinent to the 
ecology of Aldabra has been missed. Specialist papers f rom the major expedi- 
tions a r e  only cited if they contain records  f rom Aldabra, though no attempt 
has been made to give complete coverage of purely taxonomic papers naming 
Aldabra species. This Bihliography also contains a number of i tems which are 
cited in Chapters 1, 2 and 3 of this Bulletin, but which do not specifically r e fe r  
to Aldabra, and these are marked with an asterisk*. 
Abbott, W. L. 1893. Notes on the natural history of Aldabra, Assumption and 
Glorioso Islands, Indian Ocean. Proc.  U.S. Nat. Mus. 16, 759-764. 
Anonymous. 1879. (Aldabra.) Geographischer Monatsbericht: Afrika. Peter- 
manns Mitteil. 25, 362. 
Anonymous. (c. 1920). Aldahra: a cora l  island pot-pourri, dealing with the 
natural history and physical geography of certain coral  islands in the 
Indian Ocean. Typescript manuscript, 14 chapters separately paginated, 
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Madagascar, den Comoren und den Inseln Ostafrikas. In A. Voeltzkow, 
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Aurivillius, C. 1922. Coleoptera (Cerambycidae) f rom the Seychelles Islands, 
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Baker, B. H. 1963. Geology and mineral  resources  of the Seychelles archi- 
pelago. Govt. of Kenya, Ministry of Commerce and Industry, Geol. Surv. 
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*Baker, B. H. and Miller, J. A. 1963. Geology and geochronology of the Sey- 
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Gardens Kew, 1894, 146-151. 
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*Baulig, H. 1956. Vocabulaire Franco-Anglo- Allemand de ~6omorphologie.  
Pub. Facult6 des Let t res  de I'Univ. de Strasbourg, Fasc. 130, 1-230. 
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on the island of Aldabra, northwest of Madagascar, by Dr W. L. Abbott. 
Proc. U.S. Nat.  us. 17, 39-41. 
Benson, C. W. 1960. The birds of the Comoro Islands: resul ts  of the British 
Ornithologists' Union Centenary Expedition 1958. Ibis, 103b, 5-106. 
Benson, C. W. 1963. Notes on some specimens mainly from Aldabra. Bull. 
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D r  Voeltzkow. Announced fo r  publication in Abhand. Senckenb. naturf. 
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s e r .  2, Zool. 18 (Percy  Sladen Expedition Reports, 7), 165-186. 
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In A. Voeltzkow, Reise in Ostafrika in den Jahren 1903-1905, Wissensch. 
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129 
Boulenger, G. A. 1911. List of the Batrachians and Reptiles obtained by Prof. 
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Bird Watching Society), 13, 48-50. 
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1. Exposed coastal cliffs, Point Hodoul. Note the extreme dissection of the champignon, and 
the intertidal algal platform. 
2. Medium-energy coastal cliffs, east of East Channel, mid-tide. 
3. Boulder zone on reef-flat at low tide, Anse cedres. 
4. Small pocket beach on medium-energy coast, near Anse c\edres, low tide. Note the perched 
beach above the cliff line. 
5. Pocket beach at Anse CGdres, mid-tide; beachrock in the foreground. 
6. Low coastal dunes, seaward coast near Takarnaka. 
7. Moderate coastal dunes, seaward coast near Clnq cases .  
8. Moderate coasral dunes wlrh coarse grasses  between Takamaka and Clnq Cases. 
9. h e s  at the south end of West Island; intertidal flat in the foreground exposed at low water. 
10. Undercut lagoon cliffs, South Island near East Channel. 
11. Undercut lagoon islets, low tide, South Island near  East  Channel. The amplitude of the 
notch i s  about 6 ft. 
12. Sand-spit at the south end of West Island, colonised by Cyperus maritimus and seedlings of 
Scaevola and Tournefonia. 
13. Por-holed surface of champignon. South Island close to East  Channel. Soil i s  found only on 
the floors of the potholes and not on the ground surface. 
14. Karst landforms in  shelly limestone on Ile Esprit. The vertical amplitude of the pinnacles 
from the flat enclosed floors ra the summit ridges i s  18 ft. 
15. Placln wlth Wxed Scrub, three miles southeast of East Channel, on South Island. 
16. Jnclsed pools and residuals on the platln surface. South Island, near Frlgate Pool. The 
ground vegeratloli i s  Fimbr~styl is  spatbacea. 
-- 
17. Surface exfoliation on platin near Frigate Pool, South Island. Some of the limestone sheets 
are completely detached. At the left of the photograph i s  a small area of mammillate lime- 
stone formed by secondary deposition. 
18. Flat platin under open Mixed Scrub, showing residuals of brown limestone 3-4 it. high, 
near Flamingo Pool, South Island. 
19, Brow11-limestone residual 6 ft high, near Flamingo Pool, South Island. The surface of the 
residual is furrowed by solution. 
20. Seaward fringe of the Mixed Scrub community south oi Takamaka. The vegetation is sparse 
and almost a l l  the shrubs and t rees  a re  dead, except for  Pandanus. 
22, Takamaka pool, showing the large Ficus in which Pteropus aldabrensis is found. 
23. Fresh water in a sernl-permanent water course at Clnq Cases. South Island, surrounded by 
dense Acrostlchurn aureum and Pandanus. 
24. Freshwater pool used a s  a tortoise wallow, surrounded by Pandanus, on South Island, three 
rnlles southeast of East Channel. 
25. Tortoises wallowing in a freshwater pool during the morning: one in the centre of the pool 
is dead. 
26. Giant land tortoise. Testudo giganrea (Photo: Q Gayrner). 
27. Tor ro~se  on the dry floor of a freshwater pool, d u r ~ n g  the dry season, near Takamaka, 
South Island. 
28. Tortoise and a Sacred Ibis, Threskiornis aethiopicus abbotti, near Frigate pool. south 
Island. 
29. Frigate-birds diving for  water  a t  F r iga t e  Pool, South Island. 
30. Juvenile Red-footed booby. Sula su l a  rubr ipes  on Polyrnnie (Photo: R. Gayrner). 
31. Red-tailed Tropic Bird, rubricauda ruhricauda, on a lagoon islet inside East 
Channel. 
32. Adult Sacred Ibis, Threskiornis aethiopicus abbotti (Photo: Q Gaymer). 

35. Male Red-Headed Fores t  Fody, -a eminentissima aldabrana, giving threat display in 
his terri tory. Note the drooped wings and tail, and ra ised head and rump feathers (Photo: 
R. Gaymer). 
36. P a i r  of Flamingos, Phoenicopterus ruber  roseus ,  wading in a brackish pool in mangrove 
on South Island (Photo: R. Gaymer). 

. 
West Island settlement. 
40. one the ramwater 'a* 
41. Fishing shack on Middle Island, at East Channel.