Distribution and habitat selection of Myotis bechsteinii in Luxembourg: implications for forest management and conservation.

Bechstein's bat, Myotis bechsteinii is a European tree-dwelling vespertilionid bat species, which has to be considered as index species for old growth broadleaved woodland. However factors affecting density and habitat selection are still poorly understood. Therefore 22 representative woodland areas in Luxembourg that are located in the central geographic range of the Bechsteins bat, were analysed. During 76 nights, forest dwelling bats were registered by intensive mist netting, 47 Bechstein bats were radio-tracked to identify tree-roosts and 24 individuals were radio-tracked on 3-5 consecutive nights to determine their foraging areas. In total 14 reproduction areas and 12 nursery colonies were localized, with the number of females ranging between 20-70 individuals (mean 34 ± 18.1 ind.). The distribution of Bechstein's bat revealed to be uneven and to be significantly positively correlated to mean temperature and the presence of Melico-Fagetum forest with a marked amount of old oak trees. Nevertheless the height, the mean precipitation and the occurrence of Luzulo-Fagetum forest is negatively correlated to the occurrence of M. bechsteinii. Altogether, 78 tree-roosts from nursery colonies were identified. Colonies use a day-roost complex and show a significant preference for woodpecker holes. Female Bechstein's bats foraged on a mean area of 46 ha (MCP) with small core feeding areas (mean: 2.1 ha) which show no, or only a small overlap with each other. Roosting and feeding sites are characterised by canopy and understorey structures similar to native woodlands. The results of this study leads to a scientific data base for conservation and long time monitoring for this bat species.