Global impacts of climate change on avian functional diversity

Climate change is predicted to drive geographical range shifts, leading to fluctuations in species richness worldwide. However, the effect of these changes on functional diversity remains unclear, in part because comprehensive species-level trait data are generally lacking at global scales. Here we use morphometric and ecological traits for 8268 bird species to estimate the impact of climate change on avian functional diversity (FD). We show that future bird assemblages are likely to undergo substantial shifts in trait structure, with a magnitude of change greater than predicted from species richness alone, and a direction of change varying according to geographical location and trophic guild. For example, our models predict that FD of insect predators will increase at higher latitudes with concurrent losses at mid-latitudes, whereas FD of seed dispersing birds will fluctuate dramatically across the tropics. Our findings highlight the potential for climate change to drive continental-sc...