Historical Biogeography and Extinction in the Hawaiian Honeycreepers

Hawaiian honeycreepers, comprising an endemic radiation of passerine birds in the Hawaiian archipelago, have suffered losses of individual island populations and the extinction of many species as a result of colonization of the islands by Polynesians and, more recently, introduced avian pox virus and avian malaria. Here, I test the idea that populations have an intrinsic tendency toward extinction regardless of the cause. The distribution of each species before the arrival of humans in the archipelago was inferred from present distribution, historical records, and fossil remains. On the basis of these records, each species was placed in one of four stages of the taxon cycle: (1) expanding or recently expanded, (2) differentiating, (3) fragmenting, or (4) single-island endemic. Subsequent extinction of individual island populations was most frequent in stage 3 species, which had already suffered loss of individual island populations, suggesting commonality in vulnerability to extinction from anthropogenic and nonanthropogenic causes.