Birds can be good indicators of terrestrial biodiversity importance, particularly areas of high endemism. In an attempt to prioritize areas of particular conservation importance to birds, BirdLife International has identified 218 endemic bird areas (EBAs) worldwide (Stattersfield et al., 1998). Endemic bird areas (EBAs) refer to areas where landbird species with restricted ranges (i.e., global breeding range of less than 50,000 square kilometers) tend to occur together. More than one quarter of all birds of the world have restricted breeding ranges, that is, they are confined to areas of less than 50,000 km2. Restricted-range birds include 816 species currently classified as threatened; this number represents more than one half of all restricted-range birds, and 74 percent of all threatened bird species.

This map shows the number of EBAs by major basin. The size of EBAs varies widely, from tiny islands of a few square kilometers to areas that cover over 600,000 km2. Most EBAs are under 30,000 km2. The majority support between 2 and 10 restricted-range species, but a few outstanding EBAs support 50 species or more. Watersheds with very high numbers of EBAs are the Amazon basin with 24 EBAs, Orinoco and Magdalena basins with 9, the Mekong with 7, and the Congo, Paraná, and Yangtze basins with 6 EBAs each. Nearly half of all EBAs are estimated to have lost more than 50 percent of their key habitats, and more than 10 percent have lost over 90 percent. The relevance of EBAs to conservation goes beyond restricted-range bird species. Analysis by BirdLife International has established that EBAs partially encompass the ranges of many widespread threatened bird species and that they include the key habitats and sites for many more widespread species, including some important migrant birds.