Avoiding a conservation pitfall: Considering the risks of unsuitably hot bat boxes

Abstract

Bat boxes are commonly deployed to mitigate the loss of bat roosting habitat. Due to a dearth of microclimate research, numerous untested commercially available bat boxes, and the uncertain impacts of a rapidly changing climate, the overheating risk presented to bats by bat boxes is largely unquantified. Based on limited research, we know many boxes overheat (i.e., temperatures >40°C). A lack of standardized protocols to evaluate microclimate and misleading information available to the public leads to a murky understanding of risks involved with deploying bat boxes. Herein, we evaluate the thermal tolerance of temperate-zone bats, delineate areas of concern regarding the risks to temperate-zone bats when bat boxes are deployed, identify strategies for reducing overheating risk, suggest methods for assessing microclimate, and provide a visual framework to assess overheating risk. Identifying suitable design and placement combinations is crucial to developing region-specific strategies to mitigate against overheating. We urge consideration of the risks involved with using bat boxes, advocate for rigorous testing before deployment, and suggest using alternatives when possible.