Meeting Abstract

16.3  Sunday, Jan. 4  The effects of age on energy storage during pre-hibernation swarming of little brown bats (Myotis lucifugus) MCGUIRE, L.P.*; FENTON, M.B.; GUGLIELMO, C.G.; University of Western Ontario, London; University of Western Ontario, London; University of Western Ontario, London lmcguir5@uwo.ca

Little brown bats (Myotis lucifugus) gather in large numbers at hibernacula in autumn to mate and prepare for hibernation. This period is known as swarming. In eastern Ontario, bats arrive in early August, and mating begins at the end of August. Mating occurs inside the hibernacula, while foraging occurs outside. Consequently bats must manage the tradeoff between foraging to build fat stores for hibernation and spending time in the mine for mating. Minimizing energy expenditure by using daily torpor may result in a net energy gain, despite decreasing energy input. In captivity, first year bats are not as effective at using torpor and therefore may not experience the same energy savings. In natural conditions, increased feeding may compensate. We estimated the energy stores of adults and first year bats throughout swarming and used plasma metabolite analysis to assess feeding performance. Size corrected body mass increased throughout swarming for adults and decreased for first year bats. Plasma metabolite analysis indicated there was no difference in the feeding of adult and first year bats. All bats foraged hyperphagically early in the swarming period, with feeding decreasing approximately co-incidentally with the first observed mating. With no difference in nutrient intake, our results suggest that first year bats suffer from increased energy costs, either through increased costs of torpor, or through increased foraging costs due to lower foraging efficiency.