Field guides are usually pocket books, designed to tell naturalists what they are looking at. This book, measuring 21 by 15 centimetres, is a bit big for the average pocket, and contains more information than many guides. The editor, Peter Ryan of the Percy FitzPatrick Institute in the University of Cape Town, has brought together a team of contributing authors, all of whom have lived and worked on the islands, and they have consulted widely. The result is a superb record of the wildlife of the world's remotest inhabited island group, illustrated by outstanding colour photographs.
The book begins with an account of the islands themselves, contributed by Peter Ryan and James Glass, a Tristan Islander who has served as the elected head of the island community and is currently in charge of its Department of Natural Resources. Succinct accounts of the topography and volcanic history of the four islands of Tristan, Nightingale, Inaccessible, and Gough are followed by descriptions of their wet and windy, but temperate, climate; the range of habitats they support; the distinctive biological features resulting from their isolation in the centre of the South Atlantic Ocean; and the history of human discovery, occupation, impact on, and conservation of the island flora and fauna. This brings out the uniqueness of many island species, evolving prior to human contact, and the recent surge of introduction of humanity's fellow-travellers. But it also records the commitment of the Tristan community and the UK government, which administers the islands as an Overseas Territory and Dependency of St Helena, to conservation. Conservation ordinances have been in force since 1976, and were up-dated in 2006, while Gough Island and Inaccessible Island are designated natural sites under the World Heritage Convention.
Most of the book, however, is concerned with describing the plants and animals of the archipelago. Inevitably, the treatment is uneven, partly because not all groups are equally well-known, and partly because space would not permit a comprehensive description of the lower plants and invertebrate animals. The result is a very thorough and well-illustrated account of all the native vascular plants, birds, and mammals, together with pictures and descriptions of the more widespread and important introduced plants and the commoner vagrant birds, and more superficial treatment of the lower plants, terrestrial invertebrates, and marine life.
The section on plants describes and illustrates 77 flowering plants (43 native to the islands including 28 endemic species or varieties found nowhere else in the world), 32 native ferns (14 endemic), and three club-mosses (one endemic). The descriptions are brief but clear, and together with the excellent photographs should make field identifications straightforward. The wider distribution of species found outside the islands, and the origins of introductions, are also indicated. The accounts of the mosses, hepatics, and hornworts (Anthocerotae), in contrast, do less than justice to groups that are very important ecologically and together have well over 300 species on the islands, and the lichens and fungi also receive scant mention. In fairness, these groups are of most interest to specialists and their inclusion would require more space than a field handbook can provide: there is scope for a future monograph when research has moved forward.
For most naturalists, sub-Antarctic islands are first and foremost breeding grounds for seabirds and seals, and the Tristan–Gough group includes some of the most important seabird islands in the Southern Hemisphere. The 22 species that breed there (four breeding nowhere else) and 21 other seabirds occurring in Tristan–Gough waters are described and, again, there are excellent photographs. Sadly, this section also sounds an alarm call, for all the three breeding albatrosses and several other species are declining, largely as a result of drowning on long fishing lines but also, in the case of the Tristan wandering albatross on Gough Island, because of attacks on chicks in winter time by the introduced house mice.
There are seven land birds endemic to the Tristan group, and all are well illustrated and described, while several other land birds that have gone off-course during dispersal or migration and drifted to the islands are also recorded and pictured. As to the mammals, Gough is the breeding ground for some 300,000 sub-Antarctic fur seals (perhaps 80% of the world population) along with a very small and declining population of elephant seals: the fur seals are also increasing at the northern islands. Both species are well described and illustrated, as are southern right whales, which breed around Tristan (but have been severely reduced by illegal whaling), and the eight other whales that occur near the islands. The introduced black rat and house mouse complete the mammalian tally.
Oceanic islands are celebrated for their impoverished land invertebrate faunas, among which a high proportion is normally endemic. The Tristan group conforms to this rule, with only some 430 known invertebrates, most introduced by people. Weevils, moths, flies, and small snails have radiated into a series of unique forms. These are described in a short section that also records the surge of introductions, some impacting on native species: on Gough Island predation by introduced mice is thought also to be doing damage. The illustrations in this section are the least satisfactory in the book, and while this can be put down to the difficulty of the subjects, it is a pity that the unique weevils and endemic Balea snails escape illustration. As with the lower plants, there is room for a specialist monograph on these invertebrates at a future date.
Finally, the guide includes a section on marine life, enormously important to Tristan because a rock lobster (Jasus tristani) fishery is the mainstay of the island economy. The Subtropical Front lies between the northern three islands and Gough, causing differences in seaweeds, but their faunas are similar (with much in common with cold-temperate South America). The commoner fishes are well illustrated, and there is a reasonable summary of the invertebrate animal groups and seaweeds. The volume concludes with a valuable advice to would-be visitors, a checklist of introduced plants, a useful bibliography, and an index.
Overall, this book is a ‘must’ for any biologist or naturalist interested in the Tristan da Cunha islands. It contains very few factual errors, and those are trivial. It is warmly commended as the best available general account of the flora and fauna of a unique group of islands. The sponsors — the RSPB, BirdLife International, the UK Overseas Territories Environment Programme, the Tristan government, and the Percy FitzPatrick Institute — together with the authors and editor are to be complimented on a most valuable contribution to sub-Antarctic biology. It is a fitting tribute to the late Nigel Wace, to whose memory it is dedicated in appreciation of his 50 years of devotion to Tristan botany and conservation. (Sir Martin Holdgate, Fell Beck, Hartley, Kirkby Stephen, Cumbria CA17 4JH.)
