Contribution of local rarity and climatic suitability to local extinction and colonization varies with species traits.

Changes in species distributions through local extinction and colonization events are a major consequence of climate change. The mechanisms underlying these processes, however, are yet to be fully understood. We investigate the effects of climatic suitability and local rarity on local extinction and colonization of British birds. We test the hypothesis that local extinction and colonization on decadal scales are driven by both climatic suitability and the prevalence of the species within an area and that the balance between these two is affected by species traits. We use spatially explicit conditional autoregressive models to determine the effect size of local rarity and climatic suitability (extracted from climate envelope models) on local extinction and colonization events. We then use phylogenetically constrained, generalized least-square models to estimate the association of extinction and colonization predictors with body mass, clutch size and national range of each species. Both local rarity and climatic suitability of an area contributed to local extinctions and colonizations, but the importance of these predictors varied between species. This interspecific variation was explained, in part, by species traits, in particular national range, which influenced the importance of local rarity and climatic suitability to both local extinction and colonization. These results further our knowledge of the mechanisms underlying changes in species occupancy due to climate change. This can inform predictive models as well as contribute to more focussed avian conservation efforts.