The Birds of the Cayman Islands: An Annotated Checklist.—Patricia E. Bradley. 2000. British Ornithologists' Union Checklist No. 19, British Ornithologists' Union, Tring, United Kingdom. 253 pp., 71 color plates, 8 figures, 9 tables, 10 appendices. ISBN 0907446-23-X. Cloth, $65.00.—The three islands in the Cayman group–Grand Cayman, Cayman Brac, and Little Cayman—form a semi-isolated archipelago in the western Caribbean roughly equidistant from Cuba and Jamaica. Those low-lying islands together have an area of 263 km2, and compared to their larger neighbors they support a correspondingly depauperate avifauna of 69 extant breeding species, including only 16 passerines. Many groups characteristic of the Greater Antilles such as the todies and Saurothera cuckoos are currently absent from the Cayman Islands, and most of the species that breed on the archipelago are widely distributed elsewhere in the West Indies, though a number are represented by subspecies endemic to one or more of the Cayman Islands.
Given the relatively small fauna of the Caymans, one might think that compiling a checklist of the avian species present would be a simple task. Instead, this sophisticated treatment of the Caymans' avian fauna surpasses the scope it its title to highlight the wealth of information now available for even comparatively simple island systems. The core of the book is 143 pages of comprehensive species accounts for all taxa that have been reported from the islands. Those accounts are more detailed than those in a typical annotated checklist, and include comprehensive information on the range, status, and abundance of each species on each of the three islands, including dates and locations of sightings and of breeding activity. For each species, specimens from the Cayman Islands housed in 16 major museum collections are also listed. This checklist summarizes information from all previous ornithological work on the islands and provides a valuable synopsis of information on topics such as habitat distributions, migration dates, and breeding phenologies that will be of interest to a wide ornithological audience.
The 56 page introduction is equally thorough, and provides informative synopses of the history of ornithological exploration and the natural history of the Cayman Islands. This introduction is divided into 12 sections, each of which is essentially a stand-alone chapter. One section discusses the likely biogeographic relationships among taxa resident on the Cayman Islands and allied populations elsewhere. The resident Cayman Islands species seem to have colonized the archipelago from a number of sources, of which Cuba is not surprisingly the most prevalent. Cayman taxa with particularly enigmatic distributions include the Caribbean Elaenia (Elaenia martinica), which is also found on offshore islands in the Yucatan and in the Lesser Antilles but which is absent from the other islands in the Greater Antilles; and the Vitelline Warbler (Dendroica vitellina), a species that closely resembles the Prairie Warbler (D. discolor) and which occurs only on the three Cayman Islands and on the tiny and highly isolated Swan Island off the eastern coast of Honduras.
Another section that I found particularly intriguing summarizes previous paleontological work on the islands and discusses changes in species composition associated with the increasingly mesic conditions of the early Holocene. Extinct Cayman Islands taxa include a robust-billed finch probably allied to the Cuban Bullfinch (Melopyrha nigra), as well as the endemic Cayman Thrush (Turdus ravidus) and an endemic subspecies of the Jamaican Oriole (Icterus leucopteryx) that persisted into the twentieth century. The combined evidence from the paleontological record and observations of species turnover during historical times suggests that those islands have had a high lability in land bird species composition. That pattern is somewhat difficult to reconcile with the large number (17) of land bird subspecies endemic to the Cayman islands, most of which presumably represent populations that have persisted long enough to differentiate morphologically from conspecific populations on other islands.
Additional sections discuss the conservation status of the Caymans' avifauna. Development pressure is high on all three islands, but especially on Grand Cayman, where much of the dry forest habitat has been degraded and much of the mangrove wetlands are slated for development. Habitat alteration on Grand Cayman presumably contributed to the extinction of the Cayman Thrush and Jamaican Oriole. Less habitat conversion has occurred on Little Cayman and on Cayman Brac, the latter of which supports both an endemic race of the Cuban Parrot (Amazona leucocephala hesterna) and colonies of several colonially breeding seabirds, including the largest Red-footed Booby (Sula sula) colony in the West Indies. The Cayman Islands were not occupied by humans during pre-Columbian times, and the two smaller islands currently have low population densities. Habitat preservation efforts targeting those smaller, relatively pristine islands would seem to be particularly timely.
The various sections of the introduction are illustrated with a number of well-drawn maps and figures, and the book includes 71 color plates comprising vegetation maps, photographs of typical habitats and land forms, and high quality photographs of many of the resident bird species. Ten appendices provide useful tables on topics such as species distributions in the Caymans and elsewhere, and on dates of occurrence for migratory taxa.
I referred to this book frequently during a recent research trip to the three Caymans Islands, although this is not a field guide per se. My only major complaint is that I had a difficult time finding a copy for sale in the United States, and no copies were available from booksellers in the Cayman Islands. This book deserves to be made more widely available by the publisher, and I hope that its thorough treatment of the Cayman avifauna will be emulated in future BOU checklist volumes for other commonwealth islands in the West Indies.
