The Gulf of Guinea islands (Bioko, Príncipe, São Tomé and Annobón) are a spectacular centre of endemism. Bioko was formerly connected to the mainland, but the others are oceanic and have always been isolated. Thus Bioko shares most of its biota with Cameroon and has only one endemic, whereas the three oceanic islands dealt with in detail in this book possess multiple endemics. Indeed, the level of avian endemism in relation to area of these islands is unparalleled globally. Despite covering barely 1,000 km2, São Tomé, Príncipe and Annobón harbour 28 endemics. Each island is designated an independent Endemic Bird Area, and the southern forests of São Tomé, where 20 endemics occur, were classified as the second most important for bird conservation in a survey of 75 forests in Africa and Madagascar (Collar & Stuart 1988). The most common species are endemic; non-endemic landbirds within the mature forests are scarce. In comparison, the 13 main islands of the Galápagos, which cover c.8,000 km2, are home to 22 endemic bird species, and the six main islands of the Hawaiian archipelago (c.16,000 km2) possess 30 endemics (to which should be added 19 extinctions). However, whereas these two famous archipelagos have attracted much attention from ornithologists, the Gulf of Guinea has been surprisingly neglected.
Ornithological research only commenced in the mid-19th century and efforts have been irregular since. Most data are difficult to access, as they were published between 1850 and 1920 in French, German or Portuguese and are scattered through more obscure journals, unpublished reports and field notes. The only English-language synthesis, based on collections made in 1928–29, was produced by Amadon (1953) and is now well out of date. The first book on the birds, by de Naurois (1994), had a relatively small impact because it consisted of a rather thin summary of the extensive (and important) research conducted by the author himself in the 1960s and 1970s. It also contained some inaccuracies and did not include information on the rediscovery of four endemic species in 1990–91. This was followed by Christy & Clarke's (1998) attractive bird guide to the islands of São Tomé and Príncipe, which contains detailed species accounts but no references and does not cover Annobón.
As a result, this new checklist is the first comprehensive book on the avifauna of the islands, synthesising what appears to be everything that has ever been written (or said) on the birds of the Gulf of Guinea, as well as presenting it in an elegant, easy-to-read style. Following the BOU checklist series template, the book is divided into an introductory section and the species accounts. Colour photographs of the different islands and habitats are presented but, apart from the three species on the cover, the wealth of endemic birds is not illustrated. The reader can, however, find them in Christy & Clarke's guide (except the two Annobón endemics) or neatly placed together in three plates of Birds of Western Africa (Borrow & Demey 2001). Finally, there is a summary checklist (including the birds of Bioko), a gazetteer and an exhaustive reference list, which itself comprises an invaluable source for future researchers. Although complete, the final index does not distinguish the main entry for a species in the systematic list section from secondary references elsewhere in the list.
The introductory section will interest anyone curious about the natural history of Africa, as it does not focus exclusively on birds. Geological, human and ornithological histories are presented, together with the climate and the habitats of the islands. The detailed topographic maps should have been reproduced larger. The introduction also reviews endemism in plants and other animal groups, thereby highlighting the global importance of the Gulf of Guinea. Those parts dedicated to birds attempt to synthesise, rather then merely collate, many different sources of information. For example, in the chapter 'Origins of the Avifauna', from the many often discordant taxonomic assessments, the authors propose a set of hypotheses explaining the relationships of each of the endemics with mainland counterparts and the most probable colonisation routes. These will require testing using molecular techniques. In 'Seasonality of Breeding', graphs based on fragmentary and dispersed data depict laying dates. Although these graphs may depart from the true picture due to the scarcity of good quality data, they do provide a baseline for future research. Throughout, the authors make good use of tables and figures to summarise information clearly and accessibly.
The species accounts are meticulous (references range from 1789 to personal communications from 2005), and an effort to resolve contradictory and erroneous information is present throughout. The authors include all local names found in the literature and collected by themselves or others on the islands, together with the Portuguese and Spanish names. Data for each island are presented under different headings for additional clarity. Out of date accounts or omissions can be found mainly amongst vagrants, because the final stages of the book's production coincided with an increase in birdwatching visits to the islands, and the authors chose to update only those records of greatest significance. In one sense, the more additions and corrections that now come forward, the more successful this book will have been.
The authors and BOU should be congratulated for having produced the first, well-researched reference book for an important but rather neglected region. It fills a gap in the ornithological literature and will fuel renewed interest in the islands. It can also serve as a much-needed tool to support efforts to conserve these fragile ecosystems; contrary to many oceanic islands, no extinctions have been documented and forest cover is still considerable, but this is set to change following the recent discovery of offshore oil reserves. As with other volumes in the BOU series, this one will certainly become a classic.