Diagnoses of hybrid hummingbirds (Aves: Trochilidae). 16.
Characterization of a striking intergeneric hybrid (Lampornis
clemenciae 3 Calypte anna) from Ramsey Canyon, Huachuca
Mountains, southeastern Arizona
Gary R. Graves
Department of Vertebrate Zoology, MRC-116, National Museum of Natural History,
Smithsonian Institution, P.O. Box 37012, Washington, D.C. 20013-7012, U.S.A.,
e-mail: gravesg@si.edu
Abstract.?A hummingbird specimen from Ramsey Canyon, Huachuca
Mountains, southeastern Arizona, represents a hybrid of Lampornis
clemenciae (Blue-throated Hummingbird) 3 Calypte anna (Anna?s Hum-
mingbird). The specimen, which constitutes the only verified instance of
hybridization between a species in the ??mountain gem?? group of
hummingbirds and a species in the ??bee?? group, exhibits a blended mosaic
of plumage characters of the parental species.
Mayr and Short (1970:54) announced
one of the more striking examples of
intergeneric hybridization discovered thus
far among trochiline hummingbirds in
a terse annotation: ??A recently collected
(Russell, unpubl.) hybrid of L.[ampornis]
clemenciae 3 Archilochus [Calypte] costae
(or possibly A. anna) has been seen by
Short.?? Although a formal diagnosis of
the hybrid was never published, the
record has been uncritically cited in the
secondary literature (Panov 1989, Powers
1999, Stiles 1999, Williamson 2000,
McCarthy 2006). My analysis indicates
that the specimen represents a hybrid of
Lampornis clemenciae (Blue-throated
hummingbird) 3 Calypte anna (Anna?s
hummingbird). Here I provide a compre-
hensive assessment of the specimen em-
ploying the methods and assumptions
outlined in Graves (1990) as modified by
subsequent papers (Graves & Zusi 1990,
Graves 1998, 1999a).
Materials and Methods
The mummified specimen was found
dead in Ramsey Canyon, Cochise Coun-
ty, Arizona, by Joan Peabody on 26 Apr
1968. The unsexed specimen (Fig. 1),
head turned to the side with wings slightly
splayed, was deposited in the University
of Arizona Zoological Collections
(No. 9359) by Stephen M. Russell. Two
notations are penciled on the specimen
label: (a) ??Calypte costae 3 Lampornis
clemenciae,?? and (b) ??5 anna 3 clem-
enciae. Note pink throat & size. ARP
[Allan R. Phillips] ?69.?? I subjected the
specimen to an analytical procedure
termed the hybrid diagnosis (Graves
1990), which focuses on the identification
of apomorphic character states in puta-
tive hybrids. Complete dominance and
polygenic inheritance of plumage charac-
ters may prevent or obscure the expres-
sion of parental apomorphies in hybrids.
When parental apomorphies cannot be
identified, the parentage of a hybrid may
be indicated, although less conclusively,
by the presence or absence of a suite of
plesiomorphic characters (Graves 1990,
Graves & Zusi 1990, Graves 1998, 1999a).
Contrary to an earlier assessment
(Baldridge et al. 1983), the specimen
appears to be an adult male in definitive
PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
120(1):106?112. 2007.
plumage as judged by the smooth maxil-
lary ramphotheca and the presence of
a large iridescent gorget and coronal
patch. Consequently, all description in
this paper refers to definitive male plum-
age. Given the migratory behavior of
North American hummingbirds, the
Ramsey Canyon specimen could have
been hatched at some distant location
(e.g., California or Sonora, Mexico).
Thus, I compared the specimen with
series of all trochiline species (National
Museum of Natural History, Smithsonian
Institution) that regularly breed in Cali-
fornia, Arizona, Sonora, and northwest-
ern Chihuahua (Friedmann et al. 1950,
Phillips et al. 1964, Howell & Webb 1995,
Russell & Monson 1998) : Calypte anna,
C. costae (Costa?s Hummingbird), Selas-
phorus platycercus (Broad-tailed Hum-
mingbird), S. rufus (Rufous Humming-
bird), S. sasin (Allen?s Hummingbird),
Stellula calliope (Calliope Hummingbird),
Archilochus alexandri (Black-chinned
Hummingbird), Calothorax lucifer (Luci-
fer Hummingbird), Heliomaster constantii
(Plain-capped Starthroat), Eugenes ful-
gens (Magnificent Hummingbird), Lam-
pornis clemenciae, Amazilia beryllina
(Beryline Hummingbird), A. violiceps
(Violet-crowned Hummingbird), Hylo-
charis leucotis (White-eared Humming-
bird), and Cynanthus latirostris (Broad-
billed Hummingbird).
Measurements were taken with digital
calipers and rounded to the nearest
0.1 mm: wing chord; bill length (from
anterior extension of feathers); rectrix
length (from point of insertion of the
central rectrices to the tip of each rectrix),
and width of the outermost rectrix (8 mm
from tip). Rectrices (R1?R5) are num-
bered from the innermost to the out-
ermost. A scatterplot of measurements
was used to illustrate size differences
among specimens. General color descrip-
tions presented in Appendix 1 were made
under natural light.
Results and Discussion
I considered three hypotheses?the
Ramsey Canyon specimen represents (i)
a color morph of Calypte anna or C.
costae, (ii) an undescribed species, or (iii)
a hybrid. The first hypothesis can be
rejected because the external measure-
ments and proportions of the specimen
are substantially different from those of
all age classes of male C. anna (Table 1)
and C. costae (Graves 2006). Although
the second hypothesis seems highly im-
probable, a handful of recognized trochi-
line species are known from one or two
specimens (Graves & Olson 1987, Graves
1993, 1999b). In any event, hybridization
must be ruled out before species status is
conferred. Evidence presented below sug-
gests that the specimen represents an
intergeneric hybrid, Lampornis clemenciae
3 Calypte anna. For brevity I refer to the
specimen as a hybrid in the remainder of
the paper.
Fig. 1. Ventral view of a probable hybrid,
Lampornis clemenciae 3 Calypte anna (University
of Arizona 9359).
VOLUME 120, NUMBER 1 107
Three plumage characters of the hybrid
facilitated the identification of its parental
species: (a) brilliant gorget; (b) brilliant
frontlet and crown; and (c) rounded white
spots at the tips of R4 and R5 (Figs. 1, 2;
Appendix). Only two of the potential
parental species, Calypte costae and C.
anna, possess brilliant frontlets that con-
trast with the remainder of the capital
feather tract (the crown but not the
frontlet of Eugenes fulgens is brilliant),
but neither species of Calypte has large
white spots on the tips of R4 and R5. This
indicates that one of the parental species
was either Calypte costae or C. anna and
that the white rectricial spots were con-
tributed by the other parental species.
Only two of the potential parental species
(Lampornis clemenciae and Heliomaster
constantii) exhibit white rectricial spots.
However, the rectrices (R3?R5) of H.
constantii are merely edged with white,
eliminating that species from further
consideration. Furthermore, the hybrid
does not express the bold white malar
stripe or white rump patch of H. con-
stantii. Thus, plumage characters quickly
lead to the conclusion that the hybrid
represents the offspring of L. clemenciae
and Calypte sp. (Mayr & Short 1970).
The inheritance of iridescent color in
hybrid hummingbirds is poorly under-
stood. However, I assume that hybridiza-
tion between L. clemenciae (blue gorget)
and C. costae (violet gorget) would pro-
duce offspring with a bluish-violet gorget.
The dull pinkish-rose iridescence emitted
by the coronal patch and gorget of the
hybrid is much more suggestive of the
expected phenotype of L. clemenciae3 C.
anna (rose-red gorget).
I tested this parental hypothesis with an
examination of size and external propor-
tions (Table 1). External measurements of
trochiline hybrids invariably fall within
the mensural ranges exhibited by their
parental species as a consequence of
a polygenic mode of inheritance (Banks
& Johnson 1961, Buckley 1982, Graves
1990, Graves & Zusi 1990, Graves 1996).
Measurements of the hybrid fall within
the cumulative range of measurements of
Lampornis clemenciae and Calypte anna.
However, morphometric data do not rule
out the possibility that Calypte costae was
the smaller parental species. In summary,
evidence obtained from plumage color
and pattern, as well as from external size
and shape, is consistent with the hypoth-
esis that the Ramsey Canyon specimen
represents a hybrid of Lampornis clem-
enciae 3 Calypte anna. As such, it is the
only documented hybrid between a species
in the ??mountain gem?? group (i.e.,
Lampornis) of hummingbirds and a spe-
cies from the ??bee?? group (i.e., Calypte)
(Bleiweiss et al. 1997).
Lampornis clemenciae occurs during the
breeding season in riparian woodland and
oak-pine forest in mesic canyons in the
Table 1.?Ranges (mean 6 one standard deviation) of measurements (mm) of adult males of Calypte
costae, C. anna, Lampornis clemenciae, and the hybrid (Lampornis clemenciae 3 Calypte anna; University of
Arizona No. 9359).
Characters
Calypte costae Calypte anna Lampornis clemenciae
Hybrid
AZ 9359(n 5 22) (n 5 10) (n 5 10)
Wing chord 41.3?45.9 (43.9 6 1.1) 48.2?50.3 (49.0 6 0.8) 74.2?77.5 (75.3 6 1.0) 60.4
Bill length 14.3?16.9 (15.6 6 0.6) 15.2?17.7 (16.3 6 0.9) 20.6?22.5 (21.6 6 0.6) 19.9
Rectrix 1 length 17.7?20.6 (19.3 6 0.8) 22.8?26.7 (24.7 6 1.1) 42.2?44.3 (43.5 6 0.7) 31.6
Rectrix 2 length 18.6?21.9 (20.5 6 0.9) 23.3?25.5 (24.5 6 0.7) 43.3?47.0 (45.3 6 1.2) 33.6
Rectrix 3 length 20.8?24.7 (22.6 6 0.9) 26.5?29.4 (28.1 6 0.8) 45.2?48.0 (46.5 6 1.1) 35.7
Rectrix 4 length 20.8?24.8 (22.8 6 0.9) 31.1?33.4 (32.1 6 0.9) 44.8?48.8 (47.0 6 1.5) 36.0
Rectrix 5 length 20.1?23.6 (22.2 6 1.0) 30.6?33.2 (31.9 6 0.9) 45.1?49.7 (47.5 6 1.6) 37.0
Rectrix 5 width 1.4?1.8 (1.7 6 0.11) 3.0?3.6 (3.2 6 0.2) 9.5?12.0 (10.5 6 0.8) 4.8
108 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Huachuca Mountains and neighboring
mountain ranges in southeastern Arizona
and Sonora (Swarth 1904, Phillips et al.
1964, Russell & Monson 1998). Although
Calypte anna has been reported as a mi-
grant and wintering visitor in southeast-
ern Arizona since the 1890s (Phillips 1947,
Zimmerman 1973), breeding in this region
Fig. 2. Top panel: ventral views of adult males: (left) Lampornis clemenciae; (middle) a probable hybrid,
Lampornis clemenciae 3 Calypte anna (University of Arizona 9359), and (right) Calypte anna. Lower left
panel: coronal iridescence of hybrid. Lower right panel: head-on view of hybrid.
VOLUME 120, NUMBER 1 109
was not recorded until the 1960s (Zim-
merman 1973). During the time period
when the Ramsey Canyon hybrid was
recovered (1968), Calypte anna was most
commonly encountered near exotic plant-
ings in urban and suburban areas, but it
also occurred sporadically in mesic mon-
tane canyons (Zimmerman 1973, Russell
1996). Hybridization between the largely
allopatric Lampornis clemenciae and C.
anna most likely occurred in the latter
habitat.
Acknowledgments
I thank Peter Reinthal (University of
Arizona) for loaning the specimen, Steve
Russell and Tom Huels for providing
information, and Richard Zusi and Ri-
chard Banks for reviewing the manu-
script.
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Fig. 3. Bivariate relationships of measurements (mm) of measurements (mm) of adult male Calypte
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anna; University of Arizona No. 9359).
110 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
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Associate Editor: Stephen L. Gardiner
Appendix 1
Comparative description of males of Lampornis
clemenciae, Calypte anna, and a probable hybrid,
Lampornis clemenciae 3 Calypte anna (University of
Arizona No. 9359). Descriptions of structural colors
are unusually subjective, as color seen by the
observer varies according to the angle of inspection
and direction of light. For this reason I use general
color descriptions.
The dorsal plumage of clemenciae is dull green to
olive-green, shading to bronzy-green on the rump
and dark bronzy-olive on the crown. The longest
uppertail coverts are bronzy or bluish-black. A thick
white postocular stripe extends from the posterior
margin of the eye down the side of the neck around
the grayish-black auriculars.
In anna, feathers of the forecrown, loral region,
and crown (anterior from a line drawn across the
crown 3?5 mm behind the eye) are tipped with rose-
red discs, forming a brilliantly iridescent cap. A
postocular stripe is absent. Plumage from the
hindneck to the uppertail coverts is green, signifi-
cantly brighter than in clemenciae.
The dorsal plumage of the hybrid combines
elements of both parental species but is more similar
to anna. In particular, feathers of the forecrown and
crown are tipped with reflective discs that emit
a pinkish-rose iridescence (Fig. 2). Scattered feathers
along the posterior margin of the crown (,5?8 mm
behind the eyes) are tipped with pinkish-rose
iridescence. The hindneck, back, and rump of the
hybrid are bronzy-green, similar in appearance to
typical clemenciae, but notably darker than in anna.
On the other hand, the longer uppertail coverts of
the hybrid are bronzy-green, considerably paler than
those of clemenciae but only slightly darker than
those of anna. A thin grayish-white superciliary
extends from the loral area to the bronzy-green
plumage on the sides of the neck.
In clemenciae, gorget feathers of the chin and
throat are gray, broadly tipped with iridescent blue
discs (narrowly margined with projecting buffy
barbs in fresh plumage). The concealed portion of
gorget feathers is dark gray or brownish-gray,
slightly paler near the rachis. The posterior margin
of the gorget is rounded. The gorget is bordered
laterally by pale buff moustachial stripes. Feathers
of the breast and abdomen are largely gray to
brownish-gray; the sides and flanks are faintly
glossed with bronzy-green. Vent feathers are white.
Undertail coverts are gray to brownish-gray, nar-
rowly to broadly margined with white.
In anna, the rose-red gorget covers the chin,
throat, and auriculars, extending laterally to form
a tapered point along each side of the throat. Gorget
feathers are pale gray, broadly tipped with iridescent
rose-red discs. Feather bases of the elongated lateral
VOLUME 120, NUMBER 1 111
gorget feathers (up to 11 mm long) are darker gray.
A very narrow transitional band of green occurs
between the gray base and rose-red disc in many
gorget feathers. The gorget is bordered posteriorly
by a band of grayish-white plumage across the lower
throat and upper breast that extends underneath the
lateral extensions of the gorget. The lower breast,
sides, flanks, and abdomen are dull green mottled
with grayish feather margins. Feathers along the
ventral midline are broadly margined with gray or
buffy-gray. Undertail coverts are bronzy-green
broadly margined with pale gray. Pale margins
become progressively wider with increasing feather
length and the longest coverts are white or very pale
gray with a diffuse, pale bronzy-green or grayish-
green spot centered over the distal portion of the
rachis.
The ventral plumage of the hybrid combines
elements of clemenciae and anna. The hybrid?s
gorget, which covers the chin, throat, and auriculars
exhibits a pinkish-rose iridescence when viewed
head-on under direct light. The longest feathers in
the lateral extensions of the gorget are ,9.0 mm.
The concealed basal portion of gorget feathers is
gray; a narrow transitional band of green occurs
between the gray feather base and terminal pinkish-
rose disc. Overall, the degree of melanization of the
basal portion of the hybrid?s gorget feathers is
intermediate between that observed in clemenciae
(dark gray) and anna (medium gray). The gorget is
bordered laterally by short grayish-white mousta-
chial stripes. The remainder of the hybrid?s under-
parts, from the upper breast to vent, is similar to
that of clemenciae, but slightly paler, particularly
near the posterior margin of the gorget and along
the midline. The undertail coverts are similar in
color and pattern to those of clemenciae but paler.
The rectrices of clemenciae and anna differ
significantly in shape and color. The broad rectrices
of clemenciae are black, glossed with indigo
iridescence. The three outermost rectrices (R3?R5)
are tipped with white. The extent of white is variable
but it generally occupies the distal tenth of R3, the
distal fifth of R4, and the distal third of R5. Rectrix
1 of anna is bright bronzy-green, rectrix 2 is darker,
particularly on the medial vane. The narrower outer
rectrices (R3?R5) of anna are gray along the margins
(especially medially), grading to grayish black along
the rachis and toward the tip.
The pattern of pigmentation and shape of the
hybrid?s rectrices are intermediate between those of
clemenciae and anna. The innermost rectrix (R1) is
black, lightly glossed with dull green. R2 is
significantly darker, exhibiting faint green irides-
cence. The outer rectrices (R3?R5) are black,
displaying a faint gloss under direct light. R3 is
tipped with a small, wedge-shaped bronzy-green
spot. The two outermost rectrices are tipped with
a white spot, which occupies the distal eighth of R4
and the distal fifth of R5. Rectrix shape in the
hybrid is roughly intermediate between that of
clemenciae and anna.
Wing color in clemenciae, anna, and the hybrid
are similar. The maxillary and mandibular ram-
phothecae of clemenciae, anna, and the hybrid are
black.
112 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON