DEFORESTATION PREDICTS THE NUMBER OF THREATENED BIRDS IN INSULAR SOUTHEAST-ASIA

The world's tropical forests are being cleared rapidly, and ecologists claim this is causing a massive loss of species. This claim has its c ritics. Can we predict extinctions from the extent of deforestation? W e mapped the percentage of deforestation on the islands of the Philipp ines and Indonesia and counted the number of bird species found only o n these islands. We then used the species-area relationship to calcula te the number of species predicted to become globally extinct followin g deforestation on these islands. Next, we counted the numbers of insu lar southeast Asian endemic bird species considered threatened-i.e., t hose having ''a high probability of extinction in the wild in the medi um-term future''-in the latest summary Red Data Book. The numbers of e xtinctions predicted from deforestation and the numbers of species act ually threatened are strikingly similar. This suggests we can estimate the size of the extinction crisis in once-forested regions from the e xtent of deforestation. The numbers of extinctions will be large. With out rapid and effective conservation, many of the species endemic to i nsular southeast Asia will soon be lost.