Bats do hibernate during the winter and is the only period of time in which they can be observed in silence. Bats sleep in groups by hanging upside down in caves, mines, trees and buildings. From time to time they do fall when the grip of their claws weakens but they fly immediately for a new grip in the near by location. The bats presented in this article were photographed in Woman’s Cave – Carpathians Mountains during their hibernation period in winter.