Evening emergence and dawn return of the noctule bat (Nyctalus noctula) were visually observed directly at the day roosts in Central Slovakia (in 2002 and 2003). The timing of emergence from, and return to, the roosts relative to the times of sunset, sunrise and civil twilight (evening and morning) was analysed. To determine the influence of external and internal factors on activity schedules, four comparisons were performed (the influence of the extent of roost illumination, reproductive status and air temperature and colony size). The evening emergence from, and the morning return to, the roosts of noctules were concentrated in the period between sunset and civil twilight, and between civil twilight and sunrise, respectively. On average, bats started leaving the tree hollows 11 min after sunset. The mean time of the start of the morning return was coincident with the time of morning civil twilight. No significant relationships between the other selected factors and activity schedules were found. Several behavioural displays were recorded during visual observations of dawn swarming.
Mammalia is a peer-reviewed journal devoted to the inventory, analysis and interpretation of Mammalian diversity. It publishes original results on all aspects of systematics (comparative, functional and evolutionary morphology; morphometrics; phylogeny; biogeography; taxonomy and nomenclature), biology, ecology and conservation of mammals.