BULLETIN FLORIDA STATE MUSEUM


 Grand Cayman Little Cayman Cayman Brac
 185 km2 24 km2 31 km2
known or suspected
breeding species:
 a. aquatic 13 12 10
 b. terrestrial 26 17 20
 total 39 29 30

These data fall within the expected ranges on a species-area curve deter-
mined by Ricklefs and Cox (1972) for small West Indian islands.
Species numbers (12-47) for the small (18-658 km2) satellite islands off
Hispaniola also generally conform to this species-area curve (Schwartz
1969).
 Bond (1934: 345) believed that "Grand Cayman has received most of
its bird life from Jamaica and Cuba, whereas Little Cayman and Cayman
Brac have derived theirs from Cuba alone . ." Certainly the breeding
terrestrial avifauna of Grand Cayman has many species in common with
Cuba or Jamaica. But of the two smaller islands only one species
(Mimocichla rubripes), which is restricted to Cayman Brac, has affinities
with Cuban birds, whereas the remaining 18 species on the smaller
islands have affinities with forms occurring in both Cuba and Jamaica.
Furthermore, the Grand Cayman avifauna includes more species related
to the Cuban avifauna than do the smaller islands.
 The extent to which the origins of all the Cayman Island avifauna
can be assessed accurately will always be speculative, partly because
such an evaluation would depend upon the taxonomic level under con-
sideration. For example, most biogeographers consider the family Paru-
lidae to be of North American origin (Mengel 1964), but Dendroica
petechia eoa, the Cayman Island form, also occurs on Jamaica. So, did
this Yellow Warbler reach the Caymans from North America (perhaps
via Cuba) and then spread to Jamaica, or follow the opposite route, or
neither one? We really do not know the answer to this and related
questions. It is nevertheless possible to assess affinities of avifaunas in
a general way, as Bond (1934, 1966a) has attempted, and one would
have to agree with Bond that by and large the Cayman Island avifauna
probably originated chiefly from Central American elements. In this
group, I would include the Columbidae, Cuculidae, Vireonidae, Coere-
bidae, Icteridae, and some Fringillidae. On the other hand, the closest
relatives to the Caymanian Amazona, Mimocichla, Colaptes, Centurus,
and Melopyrrha are presently Cuban. Contributions from Jamaica de-
pend partly upon one's viewpoint but quite likely these include Chor-
deiles minor, most or all of the four species of Tyrannidae, Dendroica
petechia, and perhaps Spindalis and Quiscalus.


Vol. 19, No. 5