The impact and implications of climate change for bats

Climate influences the biogeography of bats, their access to food, timing of hibernation, reproduction and development, frequency and duration of torpor and rate of energy expenditure. Empirical data on the impact of climate change on bats are a cause for concern as current increases in global temperature are one fifth, or less, of those expected over the next century. We review observed impacts of climate change on bats and identify risk factors allowing species-specific predictions. The impact on species is reviewed in relation to six aspects, namely foraging, roosting, reproduction, biogeography, extreme weather events and indirect effects of climate change. For some aspects of species' ecology, there are insufficient data available to make accurate assessment of impacts. We identify seven risk factors encompassing three broad aspects: biogeography - small range size, high latitude or high altitude range and a range occupying a geographic area likely to become water stressed; foraging niche - frugivory and species restricted to aerial hawking; dispersal ability - species with restricted dispersal behaviour. We use the European and north-west African bats as a case study to assess the relative risk of climate change to individual species. Risk scores are compared with existing International Union for Conservation of Nature conservation assessments providing further insight into the conservation outlook for individual species. We provide a base for Chiroptera to be incorporated into future frameworks of risk assessment and identify areas that require further research.