ATOLL RESEARCH BULLETIN NO. 495 BIODIVERSITY SURVEYS AND CONSERVATION POTENTIAL OF INNER SEYCHELLES ISLANDS - EDITED BY MICHAEL J. HILL ISSUED BY NATIONAL MUSEUM OF NATURAL HISTORY SMITHSONIAN INSTITUTION WASHINGTON, D.C. U.S.A. JULY 2002 ACKNOWLEDGMENT The Atoll Research Bulletin is issued by the Smithsonian Institution to provide an outlet for information on the biota of tropical islands and reefs and on the environment that supports the biota. The Bulletin is supported by the National Museum of Natural History and is produced by the Smithsonian Press. This issue was financed by Nature Seychelles(former1y BirdLife Seychel1es)and distributed with funds from Atoll Research Bulletin readers and authors. The Bulletin was founded in 1951 and the first 117 numbers were issued by the Pacific Science Board, National Academy of Sciences, with financial support from the Office of Naval Research. Its pages were devoted largely to reports resulting from the Pacific Science Board's Coral Atoll Program. All statements made in papers published in the Atoll Research Bulletin are the sole responsibility of the authors and do not necessarily represent the views of the Smithsonian nor of the editors of the Bulletin. Articles submitted for publication in the Atoll Research Bulletin should be original papers in a format similar to that found in recent issues of the Bulletin. First drafts of manuscripts should be typewritten double spaced and can be sent to any of the editors. After the manuscript has been reviewed and accepted, the author will be provided with a page format with which to prepare a single-spaced camera-ready copy of the manuscript. COORDINATING EDITOR Ian G. Macintyre ASSISTANTS William T. Boykins, Jr. Kay Clark-Bourne Kasandra D. Brockington EDITORIAL BOARD Stephen D. Cairns Brian F. Kensley Mark M. Littler Wayne N. Mathis Jeffrey T. Williams Joshua I. Tracey, Jr. Warren L. Wagner Roger B. Clapp David R. Stoddart Bernard M. Salvat PUBLICATIONS MANAGER A. Alan Burchell Smithsonian Institution PO Box 37012 National Museum of Natural History MRC-125 Washington, DC 20013-7012 (MRC-163) Smithsonian Institution (MRC-163) PO Box 37012 (MRC-166) National Museum of Natural History (MRC-169) (Insert appropriate MRC code) (MRC-159) Washington, DC 20013-7012 (MRC-137) (MRC-166) Smithsonian Institution PO Box 37012 National Biological Survey MRC-111 Washington, DC 20013-7012 Department of Geography 501 Earth Sciences Building University of California Berkeley, CA 94720 Ecole Pratique des Hautes Etudes Lab de Biologie Marine et Malacologie Universite de Perpignan 66025 Perpignan Cedex, France Smithsonian Institution Press ATOLL RESEARCH BULLETIN NO. 495 PAGES PREFACE ............................................................................................................. Michael J. Hill INTRODUCTION AND METHODS.. .......................... Michael J. Hill, Terence M. Vel Kathryn J. Holm and Nirmal J. Shah BIRD ...................................................................... Michael J. Hill, Terence M. Vel, Kathryn J. Holm, Steven J. Parr and Nirmal J. Shah CONCEPTION ................................................ Michael J. Hill, Terence M. Vel, Kathryn J. Holm, Steven J. Parr and Nirmal J. Shah COUSIN ................................................................................... Michael J. Hill, Terence M. Vel, Kathryn J. Holm, Steven J. Parr and Nirmal J. Shah CURIEUSE .............................................................................. Michael J. Hill, Terence M. Vel, Steven J. Parr and Nirmal J. Shah DENIS ...................................................................................... Michael J. Hill, Terence M. Vel, Kathryn J. Holm, Steven J. Parr and Nirmal J. Shah FELICITE ............................................................................... ~ i c h a e l J. Hill, David R. Currie, Terence M. Vel and Rodney Fanchette GRANDE SOEUR .................................................................. Michael J. Hill, Terence M. Vel, Steven J. Parr and Nirmal J. Shah MARIANNE ................................................................................... Michael J. Hill, Pat Matyot, Terence M. Vel, Steven J. Parr and Nirmal J. Shah NORTH ................................................................................... Michael J. Hill, Terence M. Vel, Kathryn J. Holm, Steven J. Parr and Nirmal J. Shah T H E R ~ S E ............................................................................... Michael J. Hill, Terence M. Vel, Kathryn J. Holm, Steven J. Parr and Nirmal J. Shah SPIDERS (ARANEAE) COLLECTED 1999-2000 ................................... Michael I. Saaristo, Michael J. Hill ASSESSING CONSERVATION VALUE OF ISLANDS IN THE INNER SEYCHELLES ......................................................................... Michael J. Hill REFERENCES .............................................................................................................................. PLATES ......................................................................................................................................... ISSUED BY NATIONAL MUSEUM OF NATURAL HISTORY SMITHSONIAN INSTITUTION WASHINGTON, D.C. U.S.A. JULY 2002 PREFACE The Republic of Seychelles is made up of 115 islands spread over an Exclusive Economic Zone (EEZ) of 1,374,000 km2 (99.97% of which is sea) in the western Indian Ocean. The islands fall into three main groups, each with a different geological character: the central or inner islands (actually the northernnlost group), most of which are predominantly granitic; the low-lying sand cays of the Amirantes and Farquhar to the South; and the raised limestone islands of the Aldabra group (Aldabra and Cosmoledo atolls, Astove and Assumption) and St Pierre. Aldabra is closer to Madagascar (450 km away) than it is to the granitic islands (Mahe is around 1,150 knl away). The inner islands and Aldabra atoll support a fauna and flora rich in endemic forms (because of the distance between the groups, few endemics are shared). Both sites have been recognised as 'Endemic Bird Areas' by BirdLife International. Aldabra atoll (which makes up approximately a third of the land area of the Seychelles) is a World Heritage Site, with a tiny human population enlployed by the Seychelles Island Foundation in the conservation of the site. Because of the remote and relatively inhospitable nature of the atoll, it has never been permanently settled and exploitation has been less intensive than in the other island groups of the nation. In contrast, the inner Seychelles islands were settled in 1770 and now support around 80,000 people (on a total land area of 232 krn2). In the past 230 years the inner islands have seen extensive habitat change with the conversion of coastal forests to coconut plantation and loss of mangroves and hill forests for timber, fuel, and the production of cinnamon. Although vertebrate extinctions appear to have been minimal when compared to other remote archipelagos, eight bird species of the granitic islands are today listed as globally threatened. Plantation agriculture in the Seychelles has through much of its history been only marginally profitable, primarily due to poor transport links with markets and the small scale of production. In the late twentieth century, falling world copra prices led to the abandonment of many plantations and the largest sectors of the economy today are fish processing for export and the tourist trade. In Seychelles, the low-volunle, high-value tourist market is based on the apparently unspoilt environment of the islands and there is undoubtedly potential for ecotourism, already developed on islands such as Cousin and Bird. Ecotourism may in turn provide opportunities for increasing th6 amount of land devoted to conservation in Seychelles through active management of tourist islands, although it should not be seen as a panacea; on small islands, even low-volume tourism can have significant environmental impacts, and very few tourists actually make the long journey to Seychelles to observe the endemic wildlife. Economic changes in Seychelles have coincided with a period of increased concern for the environment and flagship species in particular; today, further human- induced extinctions of Seychelles endemic vertebrates seem unlikely. The Seychelles Magpie Robin Recovery Programme initiated by Nature Seychelles in 1990 is a good example of long-term commitment that has led to a major increase in population and range of this endangered bird. However, the intense pressure of development and stochastic events, such as the introduction of novel alien species, are real threats to habitats and endemic species in Seychelles. The work described in this volunle was carried out as part of the project 'Management of Avian Ecosystems in Seychelles', funded by the Global Environment Fund through the World Bank and inlplemented by Nature Seychelles. The aim of the island assessment programme was to survey a range of medium-sized islands in the inner Seychelles in order to assess their current biodiversity value and potential to support endangered endemic vertebrates, particularly birds. The standardised survey methods were carried out on 10 islands (of 40 in the island group), making this the most extensive such survey in the Seychelles since the early twentieth century when expeditions in 1905 (the Percy Sladen expedition) and 1908 (led by J. Stanley Gardiner) contributed greatly to the understanding of the flora and fauna of Seychelles (although the objectives of these expeditions were largely taxonomic). The collection of papers in this volume presents the results of the island assessments. The first chapter gives a summary of the methods used and provides further background to the project. In the following chapters, each island is treated in turn, with data on the biodiversity of each island, in addition to its historical and geographical context, and conservation recommendations to enhance its biodiversity value. In a final summary chapter, the potential importance of each to conservation of Seychelles endemic vertebrates is discussed. Michael J Hill Nature Seychelles (formerly BirdLife Seychelles) May 2002 vii ACKNOWLEDGEMENTS The island assessment work described in this volume was carried out as part of the World Bank-Global Environment Facility (GEF)-funded project, Manageinent of Aviaiz Ecosystems in Seychelles, coordinated by Nature Seychelles. We would like to thank the owners and managers of all islands visited for their pern~ission for the work, and in many cases active assistance in the fieldwork. In particular: Bird Island Lodge, Serge Robert (Bird Island); Marine Parks Authority Seychelles, Kevin Hoareau (Curieuse Island); Denis Island Development Company and Mason's Travel (Denis Island); North Island Ltd., Richard Slater-Jones and Mark Coetzee (North Island). The Marine Parks Authority of Seychelles provided transport to Conception, Curieuse, and Therese. Fieldwork was carried out by a team of four to six people, and on each island the core team of three was joined by several workers, most from the Seychelles Ministry of Environment and Transport, the Ministry of Culture or Nature Seychelles. These included: Pierre-Andre Adam, Eugene Annacoura, Majella Athanase, Terence Athanase, Allain Camille, Perley Constance, Laura Davis, Marcel Dufrkne, Joseph Francois, Barbara Hoareau, Camille Hoareau, Marline Isodore, Terry Jules, Victorin Laboudallon, Allan Marguerite, Charles Morel, Roland N o h , George Ravinia, Dr Gerard Rocamora, Andy Roucou, Roland Tambarra, Jose Tirant, Terence Valentine, and Roy Youpa. The work described in this volume would have been impossible without the assistance of these field workers. We would also like to thank those at Nature Seychelles who provided invaluable logistic support, including Dave Currie, Kerstin Henri and James Millett. The National Archives and Museums (Ministry of Culture and Information, Seychelles), provided historical records, the National Meteorological Services (Ministry of Environment and Transport, Seychelles) gave access to unpublished weather data, and the Geographical Information Systems (GIs) section of the Ministry of Land Use and Habitat provided recent aerial photographs of the islands. Maps for these reports were prepared by Rishabh Jivan. Specimens collected in the course of fieldwork were identified by John Noyes of the Natural History Museum, London (wasps), Michael Saaristo of the Zoological Museum, University of Turku (spiders), Pat Matyot (beetles, Orthoptera, phasmids) and Gillian Watson of Commonwealth Agriculture Bureau (CABI: soft bugs). A number of people contributed to the development of island assessment methods and assisted with the preparation of these reports, including Clive Hambler (Oxford University), Don Merton (Department of Conservation, New Zealand), James Millett and Steve Parr (Nature Seychelles). The authors would also like to thank David Stoddart, Ian Macintyre, Roger Clapp, Wayne Mathis and George Zug for comments on the manuscript.