(Uploaded by Plazi for the Bat Literature Project) The insectivorous bat Myotis lucifugus typically aspp-ends significant amounts of time in non-foraging activities portions the night into two foraging periods separated bywahnile away from day or night roosts, variations in the time interval of night roosting. During this interval, many bats occuapnyd duration of feeding bouts should be reflected in temporal roosts that are used exclusively at night and are spatially sepaarsapteects of night roosting behavior. Conditions that may influence from maternity roosts. The proportion of the night which bthates time and duration of foraging flights and night roosting spend roosting, and thus the proportion spent foraging, vpaerryiods include: 1) temporal aspects of prey activity, 2) prey both daily and seasonally in relation to the reproductive conadbi-undance, 3) predator activity, and 4) energetic constraints. tion of the bats, prey density, and ambient temperature. A singFloer, these bats, energetic considerations are complex, as they continuous night roosting period is observed during pregnanincycl.ude day-to-day variations in costs of flight and thermor?gulaDuring lactation, females return to maternity roosts betwteioen as well as seasonal changes in energy demands of reproducforaging bouts, and night roosts are used only briefly and sportaido-n. In this paper, we examine night roosting behavior of M. ically. Maximum use of night roosts occurs in late summer aflutecrifugus to estimate the variability in nocturnal time budgets young become volant. Superimposed upon these seasonal treanssdosciated with season, reproductive condition, prey density, and is day-to-day variation in the bats' nightly time budget. Leonnvigronmental conditions. night roosting periods and short foraging periods are associated with cool nights and low prey density. This behavioral response Materials and Methods may minimize energetic losses during periods of food scarcity.