Thermoenergetics of Indiana Bats

Date of Graduation

Fall 2007


Master of Science in Biology



Committee Chair

Thomas Tomasi


Indiana bat (Myotis sodalis) populations continue to decline despite current conservation efforts. Recently, the effects of climate and microclimate on the hibernation of this species have come into focus. As hibernacula temperatures in several caves have increased, the metabolic rate of hibernating bats should increase, resulting in faster utilization of the bats' stored energy reserves; bats use more energy to maintain their torpid state at higher temperatures and arousals may occur more frequently. This increase in metabolism sacrifices energy reserves and if reserves are depleted, bats may be unable to reproduce in the spring due to poor body condition, or ultimately, not survive winter. Knowing the temperature range that provides the greatest success for hibernation (minimal metabolic rates) will contribute to conservation efforts of this endangered species. To determine the effects of microclimate on the hibernation of the Indiana bat, we quantified energy budgets of Indiana bats at several ambient temperatures to determine the optimal hibernation temperature (i.e., with the greatest amount of energy savings). Bats were housed in an environmental chamber that mimicked cave conditions of 4-6°C and 77+% humidity. Arousal patterns at target temperatures were determined at 3,5,7, and 9°C by the use of iBBat data loggers affixed to the bat's back. Oxygen consumption rates at 1,3,5,7, and 9°C were measured in metabolic chambers. Metabolic rates declined with decreasing temperature to 5°C, then increased to 1°C. Arousals accurred more frequently at higher temperatures, leading to the conclusion that bats hibernating at higher temperatures are more likely to deplete energy reserves prior to the end of the hibernation season. Successful hibernation of Indiana bats could be enhanced with hibernacula that provide for the lowest energy needs.


Myotis sodalis, Indiana bat, hibernation, thermoenergetics, temperature requirements

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© Christin M. Dzurick