What ecological characteristics put native birds at risk of extinction over 1000 years ago on remote Pacific archipelagos? To answer this question, I gathered data on body size, diet, ecological habits, and phylogenetic lineage of all known indigenous, non-migratory, land and freshwater birds of several archipelagos. Extinct species were divided into "prehistoric" and "historic" extinction categories based on the timing of their latest occurrence. Prehistoric species lists reflect numerous subfossil assemblages on Pacific islands. I compared the ecological selectivity of the pre-European extinction event to later "historic" extinctions using Kolmogorov-Smirnov tests. Size bias was quantified by logistic regression. Regression trees were used to predict probability of extinction based on five ecological predictor variables (body size, feeding guild, endemicity, nest location, and flightlessness). Prehistoric extinctions showed a strong bias toward larger body sizes, although many small, specialized species also disappeared. In contrast, medium-sized species showed the highest extinction rates among historic extinctions. This pattern implicates a different suite of human impacts in the historic versus the prehistoric extinction.