The Importance of Inland Cliffs and Quarries for Bats

Abstract

Although cliffs may play an important role in bat ecology (offering natural roosting sites and thermally favourable foraging habitat), there are surprisingly few systematic investigations of bat activity in cliff habitats compared to other habitats. We carried out systematic recordings of bat calls at inland cliff habitats (comprising natural cliffs and quarries) and compared them to three other habitat types (water bodies, settlements and forests) in order to better understand the importance of cliff habitats for bats. A total of 38,440 call sequences were recorded during this study. Overall bat activity at cliff habitats was comparable to activity at water bodies and settlements but was much higher compared to forests. Median activity in forests was only 6% of that in other habitat types. In total, we recorded a minimum of 19 bat species (16 determined to the species level and three representing indistinguishable species pairs). At cliff habitats, 18 species were recorded, representing at least 75% of the 24 bat species with recent records from Carinthia, Austria, including many threatened species. Two species exhibited a significant preference for cliffs over other habitat types: Eptesicus serotinus and Hypsugo savii, the latter of which is known to be a cliff habitat specialist. Bat assemblages in cliff habitats and settlements tended to be more similar compared to other habitat types, a finding that may contribute to our understanding of the urban ecology of bats. The results of our study emphasise the importance of inland cliff habitats for bats and thus, the preservation of abandoned quarries is a significant conservation measure for bats. Moreover, studies focusing on possible negative impacts of rock climbing on bat activity and roosting behaviour of bats are needed.