Effects of historical and contemporary factors on global patterns in avian species richness

Aim The aim of this study was to determine how regional and historical factors influence global patterns in avian species richness. Location Global. Methods Using a comprehensive data set including 710 World Wildlife Fund terrestrial ecoregions covering nearly all the land surface of the Earth, avian species richness was compared among six biogeographical regions after accounting for sample area, elevational range and climate. Analysis of variance and multiple regressions were used. Spatial autocorrelation in model residuals was accounted for. Results Significant effects of region on avian species richness were found in nearly all comparisons between biogeographical regions. Main conclusions Regional and historical processes have played a role in regulating large-scale avian species richness patterns across the globe. Avian species richness in different regions of the world cannot be accurately predicted by a single global model. Avian species richness in areas of similar environments may differ substantially between regions, and thus avian species richness in one biogeographical region cannot be predicted using the richness-environment relationship derived from the data of another biogeographical region, even one with similar environments.