, Volume 96, Issue 10, pp 1235–1240 | Cite as

Hibernation and daily torpor minimize mammalian extinctions

  • Fritz GeiserEmail author
  • Christopher Turbill


Small mammals appear to be less vulnerable to extinction than large species, but the underlying reasons are poorly understood. Here, we provide evidence that almost all (93.5%) of 61 recently extinct mammal species were homeothermic, maintaining a constant high body temperature and thus energy expenditure, which demands a high intake of food, long foraging times, and thus exposure to predators. In contrast, only 6.5% of extinct mammals were likely heterothermic and employed multi-day torpor (hibernation) or daily torpor, even though torpor is widespread within more than half of all mammalian orders. Torpor is characterized by substantial reductions of body temperature and energy expenditure and enhances survival during adverse conditions by minimizing food and water requirements, and consequently reduces foraging requirements and exposure to predators. Moreover, because life span is generally longer in heterothermic mammals than in related homeotherms, heterotherms can employ a ‘sit-and-wait’ strategy to withstand adverse periods and then repopulate when circumstances improve. Thus, torpor is a crucial but hitherto unappreciated attribute of small mammals for avoiding extinction. Many opportunistic heterothermic species, because of their plastic energetic requirements, may also stand a better chance of future survival than homeothermic species in the face of greater climatic extremes and changes in environmental conditions caused by global warming.


Energy expenditure Foraging requirements Survival rates Global warming Unpredictable climate 



We would like to thank Christine Cooper, Chris Johnson, Gerhard Körtner, Bronwyn McAllan, Chris Pavey, Alexander Riek, and Phil Withers for discussions, constructive comments on the manuscript, and statistical advice. The Australian Research Council supported the work.


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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  1. 1.Centre for Behavioural and Physiological Ecology, ZoologyUniversity of New EnglandArmidaleAustralia
  2. 2.Research Institute of Wildlife EcologyUniversity of Veterinary MedicineViennaAustria

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