SELECTIVITY OF HOLOCENE AVIFAUNAL EXTINCTIONS IN THE TROPICAL PACIFIC

Can Holocene avian extinctions on Pacific islands be used to model extinction risk in modern birds? To answer this question, I gathered ecological data on all known indigenous, non-migratory, land and freshwater birds of tropical Pacific archipelagos. Using remains from numerous subfossil assemblages on Pacific islands, I compiled a species list for each island and estimated body mass and dietary constraints for extinct species. Extinct species were divided into “prehistoric” and “historic” extinction categories based on the timing of their latest occurrence. I compared the ecological selectivity of the extinction event to modern extinct and endangered species (from IUCN Red List) using Kolmogorov-Smirnov tests. Size bias was quantified by logistic regression. Regression trees were used to predict probability of extinction for endangered birds based on factors important in ancient extinctions. Prehistoric extinctions showed a strong bias toward larger body sizes, although many small, specialized species also disappeared. This pattern underscores the influence of body size on extinction risk in today's avifauna.