In-situ responses of temperate-zone bats to climate change.

There is growing evidence that human-induced climate change poses a major threat to bats. As climate change progresses, we can only hope to mitigate its negative effects on bat populations by gaining a more comprehensive understanding of the complex interactions of all the factors involved. Drawing on recent evidence, largely from long-term field studies of individually marked bats, we discuss the multiple impacts-positive and negative-of climate change on temperate heterothermic bats and their responses to climate change in situ. For example, there is increasing evidence that warmer summers and milder winters are leading to changes in the seasonal phenology of bats, which in turn may lead to species-specific changes in demography, morphology, physiology, food availability, and roost use. We also highlight open research questions on the responses of bats to climate change. This includes better data on population trends and the underlying direct and indirect climate-related causes for changes in mortality and reproductive success. In order to assess the long-term impacts of climate change on bats, more information is needed about the relative importance of phenotypic plasticity and evolutionary adaptation in the responses of bats to climate change.