SYMP 18-5
Ecology, historical extinction, and the conservation of island birds
Recent developments in the study of island biogeography have moved the field from emphasizing equilibrium to appreciating the dynamic nature of island ecosystems. Nowhere is this more true than in the study of island birds. The archaeological and fossil record of islands makes it possible to reconstruct a detailed history of the ecology and diversity of island birds over the past several millenia. In particular, extinctions and introductions of birds have altered the community structure and ecological function of island bird communities, with possible effects on ecosystem function and services provided by birds. We compiled a database of native extinct, native surviving, and naturalized introduced landbirds of islands globally. Functional trait data for each species included body mass, activity period, diet, and foraging niche. We estimated the functional diversity of each island community using four metrics and examined temporal shifts in taxonomic & functional diversity and community structure.
Results/Conclusions
Recent compilations suggest that more than 980 species of birds have disappeared from the Pacific islands alone, making it one of the largest recognized impacts of humans on other species to date. Large-bodied, flightless, and endemic species, and those with specialized diets were most likely to fall victim. We observed significant niche shifts in island bird communities after Holocene extinctions, with significant declines in mean body mass, meat-eating, and ground foraging, and increases in frugivory and canopy foraging. The modern introduction of birds to islands caused additional changes to niche structure of the community, often shifting the community further away from the prehistoric baseline. Functional diversity of island bird communities showed a strong biogeographic signal, including effects of isolation, area, and elevation. Our work suggests that accounting for species functional roles allows a more integrative understanding of biodiversity and ecosystem function in a rapidly changing world.