HABITAT PREFERENCE AND FLIGHT ACTIVITY OF BATS IN A CITY

Pipistrellus pipistrellus, Eptesicus serotinus, Nyctalus noctula, N. l eisleri, Myotis daubentonii, M. myotis, unidentified small Myotis spp. and Plecotus spp. were recorded during bat detector transects within a central European city of 350,000 inhabitants. Bats were recorded in all seven habitat types under study, the levels of activity for each s pecies and habitat type were significantly different. The relative act ivity of the whole bat community was highest in old outskirts (low den sity housing) and at the river, and lowest in the city centre and new housing estates (high density housing). Significant differences were f ound in the timing of bat activity during the night and the season. Wi thin the first two hours after sunset, relative activity of P. pipistr ellus and E. serotinus was highest in the first 0.5 h and decreased th ereafter. In N. noctula, it was highest during the second and third 0. 5 h and in Myotis spp. it was low in the first 0.5 h and increased til l the end of monitoring. Flying bats were recorded from March till Oct ober; the lunar cycle had no significant effect on the amount of fligh t activity. The relative activity of E. serotinus was positively corre lated with temperature. No significant correlation was found between t he activity of bats and the number of trees and streetlamps per transe ct. Comparison with the results of an earlier visual census showed tha t more bats were recorded acoustically than visually except in the cit y centre. This is attributed to the effect of white streetlamps during the visual census. During the acoustic census, most white lamps were replaced by yellow lamps which biased the impact of lamps on bat traff ic. Nevertheless, bat species known to benefit from white streetlamps remained the most common foragers within the city.