Asian birds on the brink: 2And we even find a suite of extreme lowland tropical rainforest birds, wide-ranging in the Sundaic region-which extends from southernmost Burma to Java-but most sensitive to habitat disturbance and least capable of surviving on the marginally more secure lower forested slopes: Wallace's Hawk-eagle Spizaetus nanus, Black Partridge Melanoperdix nigra, Crestless Fireback Lophura erythrophthalma, Large Green-pigeon Treron capellei, Short-toed Coucal Centropus rectunguis, Sunda Nightjar Caprimulgus concretus and Blue-banded Kingfisher Alcedo euryzona. These species, none of them particularly large, seem to be sharply at risk from the intense fragmentation and isolation of their habitat-and of course it is only in the past few years that we have woken up to the extent of the deforestation crisis in the Sundaic lowlands (see, e.g., '7,000 hornbills a day' in the previous Bulletin's Chairman's Letter). By contrast, the (fewer) threatened passerines that share this habitat are almost all confined to either Borneo or Sumatra rather than being spread through most of the biome. This bias towards non-passerines in what one might call the taxonomy of endangerment is also revealed in the breakdown of species by degree of threat. There are three categories; in order of increasing intensity they are Vulnerable, in which non-passerines outnumber passerines 135 to 82, Endangered, where the proportions are 43 to 22, and Critically Endangered, 31 to 10, so that the non-passerine percentage for each respective category is 62%, 66% and 76%. Again this reinforces the point that the possession of a large body is a liability uncompensated by the possession of a large range.
Range size is, however, a critical element in determining conservation status. Looking again at the list of Critical species it is immediately striking how many of them are confined to relatively small islands: 21 of the 41 are scattered between Okinawa, Amami, Mindoro, Negros, Panay, Cebu, Tawitawi, Sangihe, Siao, Buru, Boano and Bali, plus Christmas Island and a curious handful of West Sumatran/West Bornean islets; another six are on the wider Philippines, Sumatra, Java and the Lesser Sundas; two are coastal; and 12 are continental (of which no fewer than six are predominantly or exclusively Indian, and two - the White-eyed River-martin Eurychelidon sirintarae and Gurney's Pitta - are the bafflingly ungraspable jewels in the crown of Thailand). Altogether 183 (57%) of all threatened birds in Asia have ranges of less than 50,000 km2, BirdLife's threshold value for identifying the restricted-range species which make up Endemic Bird Areas; but more interestingly as many as 62 of them occupy ranges of as little as 100-5,000 km2, with 51 in the range 5,000-20,000 km2. Birds with what are essentially linear habitats, at least for large parts of their life cycles, represent a significant and increasing problem. Species like the Indian Skimmer Rynchops albicollis, Masked Finfoot Heliopais personata and some of the kingfishers (Blue-banded) which ply up and down rivers, and shore- and seabirds like Chinese Egret Egretta eulophotes, Spotted Greenshank Tringa guttifer, Spoon-billed Sandpiper Eurynorhynchus pygmeus and Saunders's Gull Larus saundersi, which forage in relatively narrow littoral areas, may appear on a map to occupy huge areas, but are in reality compressed into miniscule one-dimensional ranges. Human disruption of these ranges-the manifold dams, the fishing disturbance, the massive reclamation of mudflats all down the Chinese seaboard-carries a heavier price for such species than we sometimes recognise.
But the pressures are everywhere. Threatened birds occur in every political unit in Asia, even the Maldives. Habitat loss or degradation affects almost every species to some degree, and it has a strong impact on 191 (59%) of them. Exploitation, whether for trade or for food, affects well over half the species, and has a strong impact on 85 (26%). It makes for a heady mix, especially with the inclusion of less encompassing but locally often very serious problems such as pollution, disturbance and invasive aliens. Small wonder that this two-part but essentially single-volume book-3,000 pages, 1.5 million words, 1,000 data contributors, 7,000 references-is possibly the biggest book ever written on birds, or indeed in the entire sphere of conservation. The reason for such size is simply this: even more important than facilitating an assessment of the threat status of a species, the detailed assembly and analysis of all the information relevant to its conservation directly helps determine the best possible and most appropriate conservation measures. Time and again you hear of management decisions being taken for species on the basis of utterly inadequate information-predictably resulting in huge wastage of time, money and human resources. Red Data Books exist, at least in part, to diminish the chances of precipitate and ill-considered responses to species crises: they are there to provide the entire constituency of concerned individuals-government officials, NGO workers, academics, members of civil society-free access to the best available evidence. Of course, researchers might be expected to do their own research, but they rarely if ever do, typically lacking the languages or access to the resources or simply the understanding of the value and relevance of any information more than 10 years old. If the team that set off a few years ago to search for the Pink-headed Duck Rhodonessa caryophyllacea on a high-altitude lake in northern Myanmar had simply read all the sources (and certainly if they had had the account assembled in Threatened birds of Asia), they could have saved themselves a lot of money and effort and heartbreak (they found a Mallard Anas platyrhynchos). |
