Energetics of arousal episodes in hibernating arctic ground squirrels

Shawna A. Karpovich, Øivind Tøien, C. Loren Buck, Brian M. Barnes

Research output: Contribution to journalArticlepeer-review

81 Scopus citations


Arctic ground squirrels overwintering in northern Alaska experience average soil temperature of -10°C. To examine energetic costs of arousing from hibernation under arctic compared to temperate conditions, captive ground squirrels were maintained in ambient temperatures (Ta) of 2, -5 and -12°C. Rates of oxygen consumption and carbon dioxide production were used to estimate metabolic rate and fuel use during the three phases of arousal episodes: rewarming, euthermia, and recooling. Respiratory quotient comparisons suggest exclusive use of lipid during rewarming and mixed fuel use during euthermia. Animals rewarming from torpor at Ta -12°C took longer, consumed more oxygen, and attained higher peak rates of oxygen consumption when compared to 2°C. Ta had no significant effect on cost or duration of the euthermic phase. Animals recooled faster at -12°C than at 2°C, but total oxygen consumption was not different. Ta had no significant effect on the total cost of arousal episodes when all three phases are included. Arousal episodes account for 86% of estimated costs of a complete hibernation cycle including torpor when at 2°C and only 23% at -12°C. Thus, due to the higher costs of steady-state metabolism during torpor, proportional metabolic costs of arousal episodes at Ta characteristic of the Arctic are diminished compared to relative costs of arousals in more temperate conditions.

Original languageEnglish (US)
Pages (from-to)691-700
Number of pages10
JournalJournal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
Issue number6
StatePublished - 2009
Externally publishedYes


  • Arctic
  • Arousal
  • Ground squirrel
  • Metabolic rate
  • Oxygen consumption
  • Spermophilus

ASJC Scopus subject areas

  • Physiology
  • Ecology, Evolution, Behavior and Systematics
  • Biochemistry
  • Animal Science and Zoology
  • Endocrinology


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