HOME-RANGE AND HABITAT USE BY THE SEROTINE BAT, EPTESICUS-SEROTINUS, IN ENGLAND

Serotine nursery roosts with less than 20 bats were found to have home ranges of at least 24 to 77 km(2) and core areas of activity from 13 to 33 km(2). The size of the range may have increased further if more individuals had been tracked, as three of the four colonies studied ha d not reached their asymptotes. The total home-range area covered by f our serotine colonies was 127.36 km(2). Excluding non-breeding bats, a density of one bat per 120 ha was estimated. However, actual density was likely to be higher if there were additional non-breeding females and immatures that were not in nursery roosts. Colonial home ranges an d core areas overlapped, with individuals from different colonies feed ing at the same sites. Individual home ranges (n = 32) varied from 0.1 6 to 47.58 km(2), but these were not used exclusively by one individua l. Around the colonial core area and breeding roosts, home ranges were used by all individuals from a single colony. It is only further from the core area that ranges appeared to be used by individuals. The dis tance from roost to feeding areas varied by up to 7.4 lan, but the bat usually commuted along lines of trees and hedges and over pastures. T his resulted in greater distances being travelled than if they had flo wn by a direct route. On average, individuals commuted distances of 8 km each night between feeding areas, with a maximum distance of over 4 1 lan. They visited between 0 and 10 feeding sites each night (mean = 2.89).