Temperature, Hibernation Energetics, and the Cave and Continental Distributions of Little Brown Myotis

摘要

Hibernation permits endotherms to survive prolonged periods of cold temperatures and reduced food supply through a combination of energy storage, microhabitat selection, and metabolic reduction. For many mammals, predictable thermal relationships define both the length of the hibernation period and the level of energy expenditure during hibernation, facilitating the ability to make precise predictions about the energetic consequences of microhabitat and latitudinal temperature gradients. Here we develop a quantitative model predicting the effect of ambient temperature on the hibernation energetics of little brown myotis {Myotis lucifugiis) and compare predictions of the model with the observed distribution of bats across thermal gradients within caves and across the North American continent. Our model predicts pronounced effects of ambient temperature on total winter energy requirements and a relatively narrow combination of hibernaculum temperatures and lengths of winter that permit successful hibernation. Empirical distributional patterns of M. lucifugus correspond closely to these predictions, suggesting that temperature effects on hibernation energetics severely constrain the distribution of bats within hibernacula at the northern limit of their range.