The World's Rarest Birds by Erik Hirschfeld, Andy Swash and Robert Still Princeton University Press According to the latest assessment by BirdLife International, 590 bird species are threatened with extinction. Of these, 197 are critically endangered, 389 are endangered and the remaining four can only be found in captivity. These 590 species are the focus of The World's Rarest Birds . Individual accounts of all of these birds are placed in seven regional directories - six continents and the oceanic islands. The accounts summarise the distribution and population of each species, and detail any threats faced and any conservation measures being undertaken. All of the species are illustrated, 515 with colour photographs and the remaining 75 - for which no photographs are available - with paintings by Polish artist Tomasz Cofta. The accounts are readable and jargon-free; the standard of the images is very high (although Cofta's paintings may not be to everybody's taste) and the design and production values are outstanding. But the book is more than this. In a series of mini-essays in the introduction and the regional directories, the authors examine in some detail the causes for the decline of bird populations and focus on families of birds that face specific conservation challenges as well as threatened bird hotspots. In light of the notion that birds "are good indicators of environmental states and changes, serving as a proxy for all biodiversity", these pages make for depressing reading. All but one of the 15 causes for decline arise from man's impact on the environment. The most serious is the clearance of forests and grasslands for agricultural purposes: commodity crops such as coffee in Brazil and palm oil in Indonesia and Malaysia. Logging compounds the problem. Other major threats include invasive species on islands, hunting and trapping, residential and commercial development, and pollution. The regional directories make us aware that the problem is not confined to remote locations. Three of the threatened species in the Asia directory - the Black-faced Spoonbill, Nordmann's Greenshank and Spoon-billed Sandpiper - are regulars at Mai Po in Hong Kong. WWF management practices have made the nature reserve a haven for migratory water birds, but such commitment to conservation in East Asia is more the exception than the rule. Mai Po lies on the East Asian-Australasian Flyway and the authors indicate that over 80 per cent of the other wetlands on the flyway are threatened with development. For example, the recent reclamation of the mudflats at Saemangeum in South Korea has already led to the death by starvation of 90,000 great knots. Similar projects are taking place along the Chinese coast, making the outlook for the birds using the flyway increasingly grim. Given the above, it can only be hoped that this beautiful book succeeds, however modestly, in its aim of increasing awareness of these threatened species - and of birds like the great knot that may well become endangered in the near future given the unsustainable path that we seem to be following.