Rear mouse bats in the autumn night
On an autumn evening, when you take a stroll through the University Park or the Botanical Gardens, you will no doubt hear small chirping sounds from the darkness and if you get lucky, you will see the silhouette of an animal against the bright evening sky. Sometimes you hear people talking about the nightly active swallows and how it is incredible that these birds manage to see anything in the dark. However, they actually cannot. Birds which fly during the night will always fly so high above ground that there is no risk to fly into anything.
The little animals that people see are therefore not swallows, but bats. Rear mouse bats to be exact, and this is the bat species which most people willingly or unwillingly encounter. The rear mouse bat hovers around buildings throughout the year. During the summer, it creates nests in low farmhouses and in the winter, it settles in the larger cities to overwinter in the high-rise buildings.
Usually, you do not hear bats as their echolocation technique, which they use for direction and to catch insects, occur at such high frequencies that the human ear cannot detect it. But the rear mouse bat’s breeding and “territory” songs are detectable to humans. This is what we hear from august until Christmas when we are strolling around outside during the evenings: the sound of lusty male rear mouse bats, which compete against each other and at the same time try to impress the females which are close by.