Meeting Abstract

48.7  Jan. 6  Overwinter patterns of body temperature of free-living arctic ground squirrels. BUCK, C.L.*; KARPOVICH, S.A.; T�IEN, O; KOHL, F; BARNES, BM; Univ. of Alaska Anchorage; Alaska Department of Fish and Game; Univ. of Alaska Fairbanks; Univ. of Alaska Fairbanks loren@uaa.alaska.edu

We previously determined that arctic ground squirrels Spermophilus parryii are naturally exposed to extreme thermal conditions while overwintering in underground hibernacula in Northern Alaska. Animals in captivity also show relatively long torpor bout lengths (TBL) and adopt the lowest core body temperature (Tb) measured in any hibernator. Since, we have investigated patterns of hibernation and Tb in free-living arctic ground squirrels on the North Slope of Alaska using small, abdominally-implanted temperature sensitive data loggers. Between 1996 and 2001, we collected Tb data from a total of 50 individual animals of known sex and age continuously over winter. Age, sex, and reproductive status of animals significantly influenced timing and patterns of daily torpor and hibernation. Adult females initiated hibernation in late summer prior to juveniles and males and resumed euthermia in spring after reproductive males. Non-reproductive males, yearlings that do not reproductively mature in their first year, ended torpor after reproductive males. Mean TBL (14.62�1.81 d) did not differ by age, sex or status; however, the euthermic phase of arousal intervals in females (0.87�.04 d) was significantly shorter on average than in males (1.03�0.09 d). The penultimate arousal was significantly shorter in duration for reproductive males (1.35�1.11 d) than either females (1.85�.21 d) or non-reproductive males (3.17�2.17 d). In total, females were hypothermic (TB<30�C) during hibernation much longer than in than reproductive males (235.89�3.86 vs. 173.76�2.84 d).