UC Santa Cruz

Temporal activity patterns of animals can indicate how individuals respond to changing conditions. Gregarious roosting bats provide an opportunity to compare activity patterns among individuals living in the same location to investigate how reproductive status or sex may influence activity budgets. We examined how the activity patterns of the nectarivorous bat Leptonycteris yerbabuenae vary depending on reproductive conditions, sex, and environmental conditions. We analyzed 5 years of individual mark-resighting data using daily detections of L. yerbabuenae marked with passive integrated transponder tags (PIT-tags) at 3 subterranean roosts on the Baja California Peninsula, Mexico. We derived 4 metrics using PIT-tag detections at roost entrances to calculate periods inside the roost and time spent outside the roost (time of emergence, returns to the roost, hours inside the roost, and hours of activity). We found differences among pregnant, lactating, and nonreproductive females for roost returns, hours inside the roost, and hours of activity outside the roost. Lactating females spent the longest time outside the roost, suggesting that the energetic demands of lactation require longer foraging bouts. Contrary to our expectations, lactating females had the fewest returns to the roost during the night, suggesting that lactating females did not shorten foraging bouts to return to nurse pups. Activity patterns differed between females and males and among seasons associated with different food availability. Females had fewer returns during the night and spent more time outside the roost than males. The time of emergence for males was earlier than for females except during the nectar season when most females are reproductively active. Differences in activity patterns among reproductive status, sex, and environmental conditions show how individuals modify behaviors to meet their energetic demands. We demonstrate how mark-resighting data from PIT-tag systems at roost entrances can be used to compare activity patterns of gregarious roosting bats.