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 Bechstein`s 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.
Metabolic rate and body temperature (Tb) reduction during torpor can provide significant energy savings for bats during inclement weather and food scarcity. However, torpor use may slow down biochemical processes including fetal and juvenile development and sperm production. Sex-differences in the timing of reproductive activity of bats in the temperate climate zone should result in differences of the thermoregulation behaviour by males and females during summer. To test this hypothesis, we studied thermoregulation of freeranging, tree-dwelling gleaning bats (Myotis bechsteinii) and trawling bats (M. daubentonii) during different reproductive periods. Gleaners and trawlers are able to forage on prey which is sitting on vegetation and the ground (gleaning) or which is slowly moving over water bodies (trawling). This prey is characterized by lower ambient temperature (Ta) dependent abundance than flying prey. We used temperature-sensitive radio transmitters to measure skin temperature (Tsk). Temperature telemetry over 144 census days revealed a significant effect of reproductive period and sex on Tsk. Pre-spermatogenic males exhibited a significantly greater Tsk reduction than females in early pregnancy. Males at the beginning of sperm production and in main spermatogenesis exhibited much more frequent and deeper temperature reductions than females in late pregnancy and in lactation. Lactating females maintained the highest Tsk of all bats. Post-lactating females reduced Tsk to the same extent or even more than males in advanced spermatogenesis. Our findings indicate that the thermoregulation of gleaning and trawling temperate bats is likely to be much less influenced by environmental conditions than that of aerial hawking bat species. We suggest that both sexes of Bechstein’s bats and Daubenton’s bats primarily adapt their thermoregulation in response to current reproductive activity.