The numbers of bird species in each IUCN Red List category that are confined to the developing and developed worlds

Based on breeding distributions

Developing countries (as defined by FAO 2001) host the great majority of the world’s globally threatened bird species and those evaluated as Near Threatened (BirdLife International 2000; see figure). The proportion of species that are confined to the developing world is much greater for this group of species (82% and 88%) than for Extinct species (59%), suggesting that threats to birds in the developing world are increasing with time relative to the developed world. It may be that species in the developed world have already passed through an ‘extinction filter’: in other words, the most susceptible species have already been driven to extinction, leaving only the more resilient ones (Balmford 1996).