DAY-ROOSTING ACTIVITY BUDGETS OF THE EASTERN PIPISTRELLE BAT, PIPISTRELLUS-SUBFLAVUS (CHIROPTERA, VESPERTILIONIDAE)

Daily and seasonal activity budgets of adult female eastern pipistrell e bats, Pipistrellus subflavus, were quantified at a maternity colony in eastern Massachusetts. Ambient and roost temperatures were recorded . Activities of roosting bats were monitored using an infrared-sensiti ve video camera. Scan sampling was used to analyze video records taken at weekly intervals from mid-May to late July 1989. Analysis of day-r oosting indicates that adult females spend an average of 77% of their time at rest, 16% alert, 7% grooming, and <1% crawling. Bats were most active immediately following their morning return to the day-roost an d just prior to their departure at dusk. Periodic bouts of activity th roughout the day were usually associated with urination and (or) defec ation, mother-pup interactions, and movements in response to changes i n roost temperature. Females were significantly more active in mortise roosts than when roosting on the open ridgepole, probably because flu ctuations in temperature in mortises were smaller. As the season progr essed, the overall time that bats spent resting decreased from 86 to 7 0%, whereas time spent alert increased from 9 to 24%; weekly fluctuati ons in the incidence of grooming and crawling showed no consistent sea sonal trends. Roost temperature, time of day, and date explained signi ficant amounts of variation in both daily and seasonal activity budget s. Females rested significantly less and were more alert after young w ere born than before, although time spent grooming and crawling did no t differ significantly between the pre- and post-partum periods. Our f indings for P. subflavus generally corroborate activity budgets previo usly reported for the little brown bat (Myotis lucifugus).