THE EFFECTS OF TEMPERATURE ON NEST PREDATION BY MAMMALS, BIRDS, AND SNAKES

Understanding how weather influences survival and reproduction is an important component of forecasting how climate change will influence wildlife population viability. Nest predation is the primary source of reproductive failure for passerine birds and can change in response to temperature. However, it is unclear which predator species are responsible for such patterns because predation events are rarely observed. We investigated whether temperature influenced predator-specific rates of nest predation by analyzing data from six prior studies conducted between 1997 and 2010 in Texas, Illinois, and Missouri that used constant-surveillance video systems to identify predators at the nests of Golden-cheeked Warblers (Setophaga chrysoparia), Black-capped Vireos (Vireo atricapilla), Indigo Buntings (Passerina cyanea), and Acadian Flycatchers (Empidonax virescens). Rates of nest predation by snakes and birds increased as daily maximum temperatures increased, whereas predation by mammals was essentially invariant in response to temperature. The relative roles of physiological versus community-level mechanisms (e.g., abundance or behavior of predators and/or alternative prey) in driving the patterns we observed remain unclear, but our data point to the need to consider important biological interactions when forecasting the effects of climate change on songbird populations.