Bechstein’s bats are typical forest dwelling bats. Unlike other bat species, they usually do not roost near humans, e.g. in attics or churches. Colonies consist of mothers and their daughters and form closed societies. Within these colonies, Bechsteins’s bats form loose associations (fission-fusion-societies). Males, by contrast, remain solitary but stay within the area and they are only sporadically found in companionship with females. Females from other colonies will not be tolerated and will be attacked as soon as they enter the roost. Migration thus is uncommon.

Bechstein´s bats are philopatric and have high recapture rates. In our ongoing study, females were fitted transponders (Pit-Tags) after first hibernation so they could be identified individually. Every year, weight, size, and reproductive success were documented. In addition, tissue samples (from adults and juveniles) and parasites living on individual bats were collected. Both individual-based analyses (individual fitness and survival probability) and group-based approaches (group behavior (e.g. group decisions, recovery from population crashes, and reactions to climate change) have been made.

Preliminary results show that Bechstein’s bats show negligible senescence in terms of mortality and fecundity. They also start lactating already after first hibernation, which was uncommon in these colonies about ten years ago. Again, this poses questions on the causes and effects on the individual and population level.

Our data helps to learn more about the demographics of Bechstein’s bats. They are a protected species of the German "Habitat Directive"; our data thus contribute valuable information for conservation and management plans.

• Fleischer, T., Gampe, J., Scheuerlein, A. & Kerth, G. (2017): Rare catastrophic events drive population dynamics in a bat species with negligible senescence. Scientific Reports 7: 7370. DOI:10.1038/s41598-017-06392-9
• Kerth, G., Blüthgen, N., Dittrich, C., Dworschak, K., Fischer, K., Fleischer, T., Limberg, J., Rödel, M.O., Obermaier, E. (2015). Anpassungskapazität von 50 Arten mit potentiell hohem Aussterberisiko gegenüber dem Klimawandel in Deutschland. Natur und Landschaft 90: 17-24.

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