RESEARCH ARTICLE Mitigating the Impact of Bats in Historic Churches: The Response of Natterer’s Bats Myotis

Bats frequently roost in historic churches, and these colonies are of considerable conserva-tion value. Inside churches, bat droppings and urine can cause damage to the historic fabric of the building and to items of cultural significance. In extreme cases, large quantities of droppings can restrict the use of a church for worship and/or other community functions. In the United Kingdom, bats and their roosts are protected by law, and striking a balance between conserving the natural and cultural heritage can be a significant challenge. We investigated mitigation strategies that could be employed in churches and other historic buildings to alleviate problems caused by bats without adversely affecting their welfare or conservation status. We used a combination of artificial roost provision and deterrence at churches in Norfolk, England, where significant maternity colonies of Natterer’s batsMyotis nattereri damage church features. Radio-tracking data and population modelling showed that excludingM. nattereri from churches is likely to have a negative impact on their welfare and conservation status, but that judicious use of deterrents, especially high intensity ultra-sound, can mitigate problems caused by bats. We show that deterrence can be used t