20.2 Wednesday, Jan. 4 Energetics and use of torpor during summer in a subtropical bat, the Formosan leaf-nosed bat Hipposideros terasensis LIU, J*; KARASOV, WH; University of Wisconsin-Madison; Taiwan Endemic Species Research Institute; University of Wisconsin-Madison email@example.com
Sex differences in patterns of torpor during the breeding season have been reported in a number of temperate bats. Less attention, however, has been paid to patterns of torpor use between the sexes in warmer subtropical areas. The 60-g subtropical Formosan leaf-nosed bat, Hipposideros terasensis (Hipposideridae), has been shown that it enters hibernation in winter and males and reproductive females use separate roosts in summer. The objective of this study was to test the hypothesis that male and reproductive female H. terasensis use different patterns of torpor during summer. Result on free-ranging telemetered bats showed that, despite a relatively warm roost temperature, both male and reproductive female H. terasensis employed torpor during summer. Reproductive females, however, used torpor less frequently and for shorter duration than males. In the laboratory, we used respirometry to measure metabolic rate of bats. The results showed that H. terasensis has a below-average basal metabolic rate (BMR) for bats. There was no significant difference in BMR or body temperature within the thermal neutral zone between males and non-reproductive females and between females in different reproductive conditions. Using our data and a time-energy model, we predicted that a 74.3 g male H. terasensis can reduce metabolism 8.6 KJ (approximately 5%, or 0.22 g fat) per day by lowering body temperature during the rest phase. Because we found that body mass of free-ranging male H. terasensis substantially increased in summer. We suggest that male H. terasensis might reallocate energy saved during daily torpor to accumulate body fat in preparation for high energetically demanding period of mating in August.