Taxonomic homogenization of the global avifauna

Biotic homogenization is seen as the consequence of preferential loss of na tive species followed by ecological replacement with widespread exotics. Ho mogenization is not random in its effects on higher taxa. Using Monte Carlo simulations (rather than binomial statistics) we find taxonomic patterns i n the risk of extinction and probability of successful introduction among b irds. Sixteen avian families selectively contain extinct or threatened bird s. Eight avian families selectively contain successfully introduced birds. Eight of these 24 taxonomically selected families have not been identified in previous studies, presumably because they are species-poor. The 22 livin g taxonomically selected families are classified into four homogenization c ategories. These categories reflect how extinction and invasion are combini ng in their effects at the family level. Range size, as indexed by island e ndemism, and human influence are the primary forces driving taxonomic homog enization patterns among birds. There is no evidence that evolutionary age influences homogenization patterns. Phylogenetic comparative analyses, whic h explicitly recognize the role of human influence, are needed to elucidate more detailed ecological correlates to homogenization trends.