Letters to Nature

Nature 418, 313-316 (18 July 2002) | doi:10.1038/nature00828; Received 21 March 2002; Accepted 22 April 2002

Climate-mediated energetic constraints on the distribution of hibernating mammals

Murray M. Humphries1,2, Donald W. Thomas3 & John R. Speakman1,4

  1. Department of Zoology, University of Aberdeen, Aberdeen AB24 3TZ, UK
  2. Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
  3. Département de Biologie, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
  4. Rowett Research Institute, Bucksburn, Aberdeen AB21 9BS, UK

Correspondence to: Murray M. Humphries1,2 Correspondence and requests for materials should be addressed to M.M.H. (e-mail: Email: murray_humphries@hotmail.com).

To predict the consequences of human-induced global climate change, we need to understand how climate is linked to biogeography1. Energetic constraints are commonly invoked to explain animal distributions, and physiological parameters are known to vary along distributional gradients2. But the causal nature of the links between climate and animal biogeography remain largely obscure2, 3. Here we develop a bioenergetic model that predicts the feasibility of mammalian hibernation under different climatic conditions. As an example, we use the well-quantified hibernation energetics of the little brown bat (Myotis lucifugus) to parameterize the model4. Our model predicts pronounced effects of ambient temperature on total winter energy requirements, and a relatively narrow combination of hibernaculum temperatures and winter lengths permitting successful hibernation. Microhabitat and northern distribution limits of M. lucifugus are consistent with model predictions, suggesting that the thermal dependence of hibernation energetics constrains the biogeography of this species. Integrating projections of climate change into our model predicts a pronounced northward range expansion of hibernating bats within the next 80 years. Bioenergetics can provide the simple link between climate and biogeography needed to predict the consequences of climate change.