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-scale shifts in avian functional diversity with implications
for ecosystem function and resilience.