DUNBAR, M.B.; TOMASI, T.E.**; University of Regina; Missouri State University: Hibernation Energetics of Eastern Red Bats (Lasiurus borealis)
Many bats use torpor to conserve energy during daily or seasonal periods of inactivity. Seasonal torpor (hibernation) allows bats to avoid thermoregulatory costs of extreme conditions. Unlike other temperate hibernating bats, eastern red bats (Lasiurus borealis) do not utilize the typical hibernacula (e.g., caves). Instead, red bats move into leaf litter during cold bouts of winter months. Because temperatures fluctuate widely at these winter roosts, our first goal was to determine whether there was a correlation between winter arousals and ambient temperature (Ta). Additionally, we measured changes in metabolism and body temperature (Tb) during hibernation and arousals at various T<>. Using these data, we estimated winter energy budgets within selected temperature profiles. Bats were captured during fall of 2003 and 2004 in southwestern Missouri and kept in environmental chambers simulating natural conditions. We assessed torpor durations using temperature-sensitive data-loggers within environmental chambers maintained at 2, 5, 10 and 15� C. Metabolism during torpor (MRt; measured as oxygen consumption rates) was assessed within metabolic chambers maintained at -5, 1, 5, 10 and 15� C. These data were evaluated for differences between gender and Ta. Our data suggest that torpor bout duration was not affected by gender and it was negatively correlated with Ta. Likewise, MRt was not affected by gender but it did vary with Ta. Tb of hibernating bats approximated Ta and the difference between these temperatures was greatest at 1� C.
