Feasting, fasting and freezing: energetic effects of meal size and temperature on torpor expression by little brown bats Myotis lucifugus

摘要: Torpor is an adaptation for energy conservation employed by many species of small-bodied endotherms. However, surprisingly little known regarding proximate factors influencing day-to-day variation in torpor expression the wild. We used open-flow respirometry to quantify nine brown bats (Myotis lucifugus, LeConte 1831) at two ambient temperatures (7 degrees C and 17 C) following either sham feeding or consumption a high-protein meal (50% 100% mass required reach satiation each individual). Food significantly increased time spent normothermic before entry but did not affect rate body cooling torpid metabolic rate. Bats fully exploit potential savings maximising their use torpor. Instead they varied such that total expenditure over course 22-h trial was balanced against gross intake immediately trial, independent temperature. This accomplished adjusting timing into (thus altering torpid), rather than modulating pre-trial also significant predictor expression, which suggests reserves combine with recent foraging success influence individuals' decisions about depth duration bouts. present evidence heat generated through digestion (i.e. increment feeding) substitute active thermogenesis sub-thermoneutral temperatures, thereby reducing energetic costs thermoregulation prior entry.