Limited refugia and high velocity range-shifts predicted for bat communities in drought-risk areas of the Northern Hemisphere

Abstract

Species occupying semi-arid and dry regions around the globe face an uncertain future due to increases in the frequency and severity of droughts. In this study we modelled the potential effect of climate change on bat communities within two high-drought risk regions of the world and assessed the magnitude and direction of the predicted shifts in climatic suitability, locating climate change refugia and identifying species at greatest risk of population declines. To do this, we compared climate suitability models for 43 species using three global climate models and three emissions scenarios for current (1950–2000) and future (2061–2080) climates within two regions where droughts are predicted to increase, the Western Palaearctic and Western North America. Our models predicted an overall reduction in bat richness with future climates. Areas projected to support high species richness in the current climate coincided with greatest predicted species loss and greatest future drought risk. For species with the potential to extend their range, high velocity range shifts would be required to keep pace with these changes, particularly in the Western Palaearctic, where additional barriers to movement include seas and areas of high human population density. Predicted refugial zones were limited and occurred in similar areas across continents (montane and high latitude with some coastal areas). The area of climate suitability was predicted to contract for around half of study species, with nine identified as species of conservation concern due to low overlap between current and future modelled ranges. The best-case scenario for bat diversity in semi-arid and dry regions in the future is likely to be reduced species richness, with many species facing rapid range expansion over challenging landscapes to access climatically suitable areas. Conservation of bats in high drought risk regions will likely depend on protection of identified refugia and networks of water sources, as well as global measures to protect biodiversity and human wellbeing, such as reduction in global carbon emissions.