Abstract
Gorman Cave in Colorado Bend State Park, Texas is a hibernaculum for a
population of nearly 500 eastern pipistrelles (Perimyotis subflavus). This study
conducted from 1995-98 addressed different stages of torpor during winter hibernation by
eastern pipistrelles. The effects of gender and environmental variables on the internal
temperature and sex ratio were assessed. Bats in hibernation are known for leaving and
returning to stages of torpor. Gender had no apparent effect on the internal temperature
of eastern pipistrelles and any variation in internal temperature was more of a synergistic
effect of environmental variables of which the strongest effects were distance from entrance of the cave, ambient temperature of roost site, and sampling time. The sex ratio
of eastern pipistrelles in the hibemaculum was determined to be I: I and occasionally was
disproportionately skewed toward females.
