This project was conducted by Ms. Michaela Gerges and Dr. Andreas Zahn from the Koordinationsstelle für Fledermausschutz Südbayern, in partnership with Dr. Guido Reiter from the Koordinationsstelle für Fledermausschutz und -forschung in Österreich. The study was undertaken between February 2010 and January 2012 and funded by German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.

Around the world, bats make seasonal migrations searching for hibernation sites or habitats with an abundant food supply. Also in Europe there are some migratory bat species, e.g. the Noctule bat (Nyctalus noctula), the Leisler’s bat (Nyctalus leisleri) or the Nathusius’s pipistrelle (Pipistrellus nathusii) (DIETZ et al. 2007; HUTTERER et al. 2005; NEUWEILER 1993). However, the routes taken by the bats and the cues used for orientation and navigation during their migrations are still unknown (DIETZ et al. 2007; FENTON 1992; HOLLAND 2007; NEUWEILER 1993).

In the context of bat migration, one assumption is that rivers with their accompanying riparian forests are of great importance as they provide guidelines for long-distance orientation and as feeding areas for migrating bats (MESCHEDE & RUDOLPH 2004). In spite of little evidence to prove this assumption, it has been shown that some migratory bat species in Bavaria typically inhabit riparian forests and concentrate there especially during migratory seasons in the spring and in the autumn (see Fig 1) (MESCHEDE & HELLER 2000).

This project investigates the importance of rivers for migrating bats in the alpine range of southern Bavaria and northern Austria. One aim of the project is to support the idea that, while migrating to alpine hibernation sites, bats use rivers as landmarks. The second aim is to evaluate rivers and riparian forests as feeding habitats for bats in general compared to other ecologically similar habitats as lakes with nearby woodland.