Birds of the Seychelles.—Adrian Skerrett and Ian Bullock. Illustrated by Tony Disley. Princeton University Press. Princeton, New Jersey. 320 pp., 53 color plates, 18 line drawings, 5 maps. ISBN 0-691-08863-2. Paper, $39.50.—The unique avifauna of the Seychelles has long deserved a field guide of this quality. Its sole predecessor (Penny 1974) did not do justice to the islands or their birds, in particular by omitting common migrants that were described in other field guides (Diamond 1975). Skerrett and Bullock's book goes to the other extreme, including figures and full descriptions of all species recorded in the archipelago and several of uncertain status.
Nearly twice as many species (250) have now been recorded in the Seychelles as in 1974. The unique biogeographic situation of the Seychelles—a tiny but ancient archipelago set on a migration route linking two continents and an island of continental dimensions (Madagascar)—has shaped its extraordinary avifauna in ways that the authors describe clearly, succinctly, and accurately. The book begins by describing the origin and location of the islands, with five clear and accurate maps at varying scales from the whole Indian Ocean west of Christmas Island, to individual islands (the largest, Aldabra Atoll). The authors distinguish between the granitic islands at the northeast end of the archipelago, and the much more numerous “outer” islands (atolls and sand-cays). They draw attention to the geological uniqueness of the granite islands, which, apart from St. Paul's Rocks in the South Atlantic, are the only oceanic islands composed of continental rather than oceanic rocks, a relic of the break-up of Gondwanaland into Africa, India, and Madagascar. Because of this origin, some of the biota (notably amphibians and some palms) are descendants of indigenous survivors rather than waifs arriving by transoceanic dispersal; although that gives the islands' biota high rates of endemism in some groups, it is not clear that any bird species can be considered relics. The relevant features of the islands' geological history are briefly sketched, highlighting the reduction in land area (from 300,000 km2 to <500 km2) as sea level rose following the last glaciation.
The major groups of islands, and the larger individual islands, are described briefly, followed by a note on the climate (tropical oceanic, as would be expected at 4–10°S), a list of plants mentioned in the text, information about the Seychelles Bird Record Committee (on which both authors are active), a glossary of (ornithological) terms used, and two fascinating pages on the origins of the bird fauna of the Seychelles. This will interest and excite any birder or ornithologist interested not only in “what is that bird,” but “where is it from, and how did it get here”—the extra questions that give a special dimension to island ornithology.
The authors paint a vivid picture of “tiny specks of rock” separated from other landmasses 65 Mya and colonized over the millennia by exhausted wind-borne vagrants. They give examples of species that have evidently colonized twice, from different directions, because different races now coexist there, for example the Green Heron [Butorides striatus] with a race of African origin (degens) in the granitic islands and one of Asian origin (crawfordi) in the outer isles. By detailing the varied origin of endemic and other native birds—from Madagascar, India, Africa, and Malaysia—they illustrate vividly the chaotic colonisation of those islands at a crossroads of the western Indian Ocean. The processes of immigration and colonization of course continue, with a Black-crowned Night Heron [Nycticorax nycticorax] arriving as a vagrant in 1992 and breeding by 1996; and a Long-tailed Cormorant [Phalacrocorax africanus] is described here as reaching Aldabra in 1999, though in the main text (p. 159) it is described as “vagrant to Aldabra and the granitics recorded in most months.”
This excellent essay is followed by a checklist before launching into the colored plates. Each plate illustrates all the plumages likely to be seen in Seychelles of three to nine species (usually four or five); the authors say all those in the same pose are to scale but we might disagree on how similar poses have to be to be the same. The first plate is of species now extinct on Seychelles, of which three are globally extinct. Many publishers of field guides would not pay for a plate of birds that would not be seen (thank you, Princeton University Press!). The practice of showing all similar or related species recorded in the Seychelles might lead to confusion and misidentification among visiting birders, were it not for the very useful introductory note to the explanatory text opposite each plate that summarizes the status of the species illustrated. Thus, if I look only at the plate showing five species of storm-petrel I might think I could expect to see any of them, but the text opposite warns me that two are vagrants between October and November, one is a vagrant in May, and the other two are of “uncertain status,” that is, I am most unlikely to see any of them! I am not sure what arguments the authors used to persuade the publisher to pursue such pictorial profligacy, which is sadly rare in field guides, but both parties are to be congratulated because this is likely to facilitate early confirmation of several species of uncertain status. The text opposite the plates gives common (English) name, scientific name, size (length for most species, wingspan for long-winged species), page of species account, and succinct distinguishing features of each plumage illustrated.
Following the plates are the species accounts, each of about half a page. These give alternative English common names as well as the common names in the other two official languages of the Seychelles, French and Creole; the Creole names are in the Seychelles orthography that will be unfamiliar to many readers, and many of them have been invented by the authors in a commendable attempt to increase awareness of ornithology among the Seychellois citizenry. (The authors also give some Creole names in their plant list). The text is clear and concise, under the headings “Description” (adult, juvenile); “Voice”; “Behaviour” (yes this is a British book and that's how it's spelt there!); “Range”; “Status”; “Threats and Conservation” (selected species); and “Similar Species”. Following the species accounts are an extensive bibliography (seven pages in small type) and indices of English and scientific names. I commend the authors for calling Gygis alba “Fairy Tern” (a name which the birds richly deserve) rather than “White Tern” and so not slavishly following the AOU (and others) in the misapplication of rules of nomenclatural priority designed for scientific names, to common names, which results in “Fairy Tern” being reserved for Sterna nereis (an Australasian clone of Least Tern [S. albifrons]) which does nothing to deserve it.
The text is generally comprehensive and accurate, but a reviewer has to earn his copy of the book so I offer a few detailed comments. There is considerable attention paid to the different subspecies found among the islands, but I believe the authors have missed a couple; in one case this has identification implications (and therefore are highly relevant to a field guide), the other adds to the biogeographic interest of the book. The first concerns Crested and Lesser Crested terns Sterna (the authors use Thalasseus, not recognised by the AOU Checklist) bergiii and bengalensis, respectively. The former breeds on Aldabra (in the southwest of the archipelago) and a few outer islands; bengalensis is a nonbreeding visitor. The comparison given here is that bengalensis is paler than bergii; I have not seen bengalensis among the granitic islands, but on Aldabra it was identifiable at some distance by being much darker than the local bergii. This suggests they are S. b. torresii, breeding in the Malay Archipelago and Australia, rather than S. b. bengalensis, which breeds from the Persian Gulf to Singapore (Harrison 1983) and might be expected in the Seychelles. If the description given by the authors is accurate for the granitic islands, perhaps the nominate race winters in the northern part of the archipelago and torresii at Aldabra and perhaps elsewhere in the archipelago. That would have a parallel on the East African coast, where the dark race (S. b. velox) of Crested Terns occurs along the southern coast of Kenya but is replaced in Tanzania by the pale race S. b. thalassina in Tanzania (Britton et al. 1980).
The second case involves the Great Frigatebird [Fregata minor] which breeds at Aldabra and roosts widely as nonbreeders, including many in the granite islands. The authors describe adult female F. minor with the eye-ring pink and bill blue-gray, but breeding females on Aldabra have both bill and eye-rink pink. However, the population breeding on Christmas Island in the eastern Indian Ocean (the subspecies F. m. minor) has the eye-ring red and the bill blue-grey (Gibson-Hill 1947); I have seen such birds roosting among typical Aldabra birds (F. m. nicolli) on Aride and suggest that this species is another example of populations of widely different geographic origin, distinguishable in the field, “wintering” (i.e. spending the nonbreeding period) in the Seychelles (in this case, on the same island). Supporting evidence is the authors' reference to juvenile F. minor with “orangey-buff” heads roosting on Aride, contrasting with white-headed juveniles characteristic of Aldabra. Buff-headed juveniles, like blue-billed females, are characteristic of the Christmas Island population.
A more systematic approach to the citation of band recoveries would be welcome; there must now be enough to merit a comprehensive listing. For example, the authors mention the spectacular movement of a Lesser Frigatebird [F. ariel] from Aldabra to near Bombay, but not the Bridled Tern [Sterna anaethetus] from Cousin Island to the Tanzanian coast or the Red-footed Booby [Sula sula] from Aldabra to an oil tanker in the Mozambique Channel.
After more than 20 years away from the Seychelles, it is reassuring to find that all the vagrants I thought I saw there (and many more) have been recorded regularly since. Only one species—a Great Black-backed Gull [Larus marinus] seen on Mahé in December 1974—remains unconfirmed by subsequent observations, although under “Similar Species” to Lesser Black-backed Gull [L. fulvus] the authors refer to L. marinus as being “extremely unlikely to reach Seychelles.”
It is impressive to see how much more is now known about the distribution and biology of birds here, much of it related to the very active conservation programs of the Seychelles Government and international agencies such as BirdLife International and the Royal Society for the Conservation of Nature. The Republic of the Seychelles has several national parks and many nature reserves and has a long tradition of conservation.
This is a fine book that belongs on the shelves of field-guide collectors, birders or ornithologists planning to visit the Seychelles, and ornithologists interested in island biology. It is attractively produced, using high-quality paper that makes it rather heavy for its size (6 × 9 1/4 inches). The cover is a little deceptive in illustrating one plumage (male Golden Oriole [Oriolus oriolus]) not yet recorded in the islands, one species not yet recorded at all (Anhinga [Anhinga rufa]) and one vagrant (Wilson's Storm-Petrel [Oceanites oceanicus]), despite the plethora of colorful birds of known or regular status that could have been shown. Scientists looking for a more technical treatment of the islands and their biota might also be interested in Stoddart (1984) which contains several chapters on birds.