Frontiers of Biogeography

The nine currently recognized species of moa (Order – Dinornithiformes; Bonaparte 1853) suffered extinction soon after New Zealand was settled by humans.  They were the result of an evolutionary radiation that produced a unique guild of birds – giant, and totally wingless species that evolved in the absence of non-volant mammals.   Recent advances in dating and paleoclimatology, and compilations of data on distributions of the nine species of moa, along with information on the geographic, topographic, climatic and edaphic characteristics of sites from which moa remains have been recovered, enabled us to test whether their evolutionary radiation truly was ‘adaptive’, producing ecologically distinct species.  Randomization, resampling analyses of moa distributions across North and South Islands revealed highly significant geographic and ecological segregation, with different species tending to occupy different islands, regions within islands, or elevations within regions.  Quadratic Discriminant Analyses demonstrated niche segregation at even finer scales, including that based on vegetation-defined habitats and on local climatic, topographic and edaphic conditions.  Moa distributions also appear to have been dynamic over time, shifting in their upper elevational limits as climatic conditions changed and vegetative zones shifted upward during the Holocene Epoch.  Our ongoing studies are building on the results presented here to explore the temporal dynamics of moa distributions, assess differential responses of moa species to natural and anthropogenic drivers, and determine how these forces may have combined to cause the extinction of moa just a few centuries ago.