Quarrels and flirting in the church roof: Big-eared mice have a varied repertoire of sounds

Male greater mouse-eared bats (Myotis myotis) have a lot to say – and every call sounds different. A new study by the Museum für Naturkunde Berlin shows that these animals not only possess a wide repertoire of vocalisations, but that these also carry individual characteristics. The researchers discovered that the males use their calls for specific purposes: some serve to defend territories, whilst others are directed at potential mates. The new findings are not only significant for behavioural research but also open up new possibilities for more effective bat conservation.

As part of her PhD, funded by the German Federal Environmental Foundation (DBU), Lisa Printz from the Museum für Naturkunde Berlin recorded thousands of calls over a three-year period in churches and attics across Bavaria. In the process, she identified 14 different types of calls, ranging from aggressive calls to complex courtship trills. Particularly striking are the so-called FM trills: courtship vocalisations that serve both to mark territory and to attract females. Each of these trills carries an individual signature that makes it possible to distinguish individual males acoustically.

“Our findings show that the males’ courtship vocalisations are highly complex and bear individual characteristics. Much like an acoustic fingerprint,” explains Lisa Printz. “These differences could make it easier for females to select a suitable mate.”

The study also reveals clear seasonal patterns: aggressive calls are common at the start of summer, whilst courtship trills peak in late summer during the main mating season. These seasonal dynamics reflect the interplay between territoriality and mating behaviour.

The new findings are significant not only for behavioural research but also for species conservation. “Using vocal analyses, we can identify key mating sites and recognise particularly sensitive phases without disturbing the animals,” says Mirjam Knörnschild from the Museum für Naturkunde Berlin. “This allows us to plan restoration work more effectively and protect key mating sites in a targeted manner.”

This has direct implications for practical species conservation: until now, conservation measures have focused on nursery roosts and winter roosts, whilst mating roosts have received less attention. However, the new study shows that males use their mating roosts over a period of years. Renovation work or construction activities at the wrong time can therefore severely disrupt mating activities. 

Through their work, the researchers provide valuable insights into the social communication and reproductive behaviour of one of Europe’s most common bat species. At the same time, the bioacoustic method opens up new possibilities for making bat conservation more effective and, at the same time, more gentle.

Publication: 

Printz, L., Fernandez, A. A., Nagy, M. & Knörnschild, M. (2025). Fighting and Flirting: The vocal repertoire of the Greater Mouse-eared Bat in mating roosts and its seasonal variation. Animal Behaviour. https://www.sciencedirect.com/science/article/pii/S0003347225003677