OBSERVATIONS ON SEASONAL CYCLE, POPULATION-PATTERNS AND ROOST SELECTION IN SUMMER COLONIES OF PLECOTUS-TOWNSENDII-VIRGINIANUS IN KENTUCKY

Limited information is available on the use of summer roosts by Virgin ia big-eared bats (Plecotus townsendii virginianus) or on the timing o f the summer reproductive cycle for this subspecies. We measured inter nal temperatures and structural characteristics of roosts, and used em ergence counts with night vision equipment and mist netting to monitor P. t. virginianus at three maternity roosts and one bachelor roost in Kentucky, during 1990, 1991 and 1992. Structural characteristics of r oosts varied. All colonies selected limestone caves except one that us ed a sandstone rock shelter. There were no differences in internal tem peratures between the rock shelter roost and a cave roost in summer 19 91. Timing of establishment of maternity colonies varied among roosts. Roost abandonment (switching) occurred with maternity colonies in cav es. Females at the rock shelter roost were pregnant on 10 May and lact ating on 17 June 1991; young were volant on 5 August. Bimodal activity patterns were observed at maternity roosts, except during lactation w hen activity of bats at roost openings persisted throughout the night. Population patterns at the bachelor roost were consistent across year s. Low numbers in the bachelor roost in mid-August coincided with the descent of testes and the onset of mating activity.