Mass hibernaculum of Pipistrellus pipistrellus in a bypass tunnel of the Slapy water reservoir, Czech Republic (Chiroptera: Vespertilionidae)

Abstract

The bat hibernaculum, situated on the right bank of the Vltava river near Třebenice, approximately 300 metres under the dam of the Slapy water reservoir (49,82232913° N, 14,43661106° E), was discovered in 2010. The bats use a bypass tunnel quarried in 1949–1951 during the construction of the dam. The first check revealed a mass winter aggregation of the common pipistrelle (Pipistrellus pipistrellus), comprising almost 4000 individuals. Since the discovery till 2017, we recorded regular wintering of 2090–4251 individuals of this bat. Moreover, we obtained data on the hibernation of other eight species at this locality: Myotis myotis, M. daubentonii, M. nattereri, M. mystacinus, Barbastella barbastellus, Nyctalus noctula, Vespertilio murinus, and Plecotus auritus. The occurrence of the soprano pipistrelle (Pipistrellus pygmaeus) was confirmed only by detection of echolocation calls and netting at the entrance to the tunnel, but not in the winter aggregation.