Analyses of globally threatened anatidae in relation to threats, distribution, migration patterns, and habitat use

New World Conservation Union criteria for globally threatened status are applied to the Anatidae (ducks, geese, and swans) at the subspecific level. Various characteristics of the 48 threatened taxa are considered. These taxa are compared to the 180 taxa that are nonthreatened to explain what aspects of a taxon's distribution, migration pattern, and habitat use make it likely to be globally threatened. Habitat loss, hunting, and exotic introductions are the major causes of globally threatened status, affecting 73%, 48%, and 33% of threatened Anatidae respectively. Although the habitat use patterns of threatened and nonthreatened Anatidae are similar, inland lentic wetland and forest inhabitants are most threatened by habitat loss, whereas marine ecosystem, grassland, tundra, arable land, and scrub dwellers are least threatened. Insular taxa are more likely to be threatened or extinct than taxa occurring on continental land masses. Nonmigratory taxa are more likely to be threatened or extinct than migratory taxa, but there is no significant difference when insular taxa are excluded from the analysis. Taxa with their breeding distribution centered above a latitude of 20 degrees north are less threatened than those found farther south. Taxa with their breeding distribution centered at or above 55 degrees north are even less threatened. Russia holds 14 threatened Anatidae taxa, more than any other country. There is an exceptional concentration of 7 threatened, migratory taxa confined to the east-Asian flyway. Despite the fact that the Ramsar Convention was established with the conservation of the Anatidae in mind, only 31% of globally threatened taxa have ever been recorded on the world's 685 Ramsar sites. For the 21 highly threatened taxa this proportion drops to 10%. Compared with globally threatened birds in general, the threatened Anatidae have a different geographical distribution but share habitat loss as the most important threat. Hunting and introductions are more important threats to the Anatidae, and trade and small population ranges are less important. All these findings have important implications for waterbird and wetland conservation programs.