Original Paper

Journal of Comparative Physiology B

, Volume 179, Issue 2, pp 155-164

First online:

Daily rhythmicity and hibernation in the Anatolian ground squirrel under natural and laboratory conditions

  • Mutlu Kart GürAffiliated withDepartment of Biology, Faculty of Science, Hacettepe University
  • , Roberto RefinettiAffiliated withCircadian Rhythm Laboratory, University of South Carolina Email author 
  • , Hakan GürAffiliated withDepartment of Biology, Faculty of Science, Hacettepe University

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We studied daily rhythmicity of body temperature (T b) before and during hibernation in Anatolian ground squirrels (Spermophilus xanthoprymnus) under natural and laboratory conditions using surgically implanted temperature loggers. Under both conditions, robust daily T b rhythmicity with parameters comparable to those of other ground squirrel species was observed before but not during hibernation. Euthermic animals had robust daily T b rhythms with a mean of 37.0°C and a range of excursion of approximately 4°C. No T b rhythm was detected during torpor bouts, either because T b rhythmicity was absent or because the daily range of excursion was smaller than 0.2°C. The general patterns of hibernation that we observed in Anatolian ground squirrels were similar to those previously observed by other investigators in other species of ground squirrels.


Circadian rhythm Hibernation Body temperature Torpor Spermophilus xanthoprymnus