Annual Cycle of Body Composition and Hibernation in Free-Living Arctic Ground Squirrels

Buck, C. Loren; Barnes, Brian M.

doi:10.2307/1383291

Cited by 204 publications

(186 citation statements)

References 30 publications

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“…A search of the literature shows that, amongst the intensively studied sciurid rodent hibernators, some enter hiber-nation at a corresponding time of the year. Reproductive female golden-mantled ground squirrels (Spermophilus saturatus) in Washington State entered hibernation 65"2 days after the summer solstice , adult female arctic ground squirrels (S. parryi) entered hibernation at 62 days (Buck and Barnes, 1999), and yellow bellied marmots (Marmota flaviventris) in Colorado at 72 days (Armitage, 1998). While many species may enter hibernation later than this, early entry into hibernation is not an unique strategy.…”

Section: Timing Of Hibernationmentioning

confidence: 99%

“…In Arctic ground squirrels the mean difference between the first animals to emerge (reproductive males) and the last to emerge (non-reproductive males) is approximately 2 weeks (Buck and Barnes, 1999). Although most marmots are communal hibernators (Arnold, 1993) and arouse closely together (Ruf and Arnold, 2000), woodchucks (M. monax) are solitary hibernators and southern woodchuck (M. monax monax) males arouse 3 weeks before females and subadult males (Snyder and Christian, 1960).…”

Section: Timing Of Hibernationmentioning

confidence: 99%

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The timing of hibernation in Tasmanian echidnas: why do they do it when they do?1

Nicol

Andersen

2002

Comparative Biochemistry and Physiology Part B: Biochemistry an

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We investigated the patterns of hibernation and arousals in seven free-ranging echidnas Tachyglossus aculeatus setosus (two male, five female) in Tasmania using implanted temperature data loggers. All echidnas showed a 'classical' pattern of mammalian hibernation, with bouts of deep torpor interrupted by periodic arousals to euthermia (mean duration 1.04"0.05 (ns146). Torpor bout length increased as body temperature fell during the hibernation season, and became more variable as temperature rose again. Hibernation started in late summer (February 28"5 days, ns6) and males aroused just before the winter solstice (June 15"3 days, ns3), females that subsequently produced young aroused 40 days later (July 25"3, ns4) while females that did not produce young hibernated for a further two months (arousal Sept 27"5, ns7). We suggest that hibernation in Tasmanian echidnas can be divided into two phases, the first phase, marked by declining minimum body temperatures as ambient temperature falls, appears to be obligatory for all animals, while the second phase is 'optional' and is utilised to varying amounts by females. We suggest that early arousal and breeding is the favoured option for females in good condition, and that the ability to completely omit breeding in some years, and hibernate through to spring is an adaptation to an uncertain climate. ᮊ

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Section: Timing Of Hibernationmentioning

confidence: 99%

Section: Timing Of Hibernationmentioning

confidence: 99%

The timing of hibernation in Tasmanian echidnas: why do they do it when they do?1

Nicol

Andersen

2002

Comparative Biochemistry and Physiology Part B: Biochemistry an

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“…Arctic ground squirrels are found throughout the tundra and alpine areas of mainland Canada, into the boreal forests of northwestern Canada, and throughout Alaska (Banfield 1974). They are obligate hibernators, emerging above ground from a 7-8 month hibernation in early-to-mid-April, with males appearing ϳ1-2 weeks before females (Carl 1971, Lacey 1991, Buck and Barnes 1999a. Mating occurs within 3-4 days of female emergence and is generally highly synchronous (usually being completed within a 2-3 week period) and promiscuous, with many litters being multiply sired (Lacey et al 1997).…”

Section: Biology Of Arctic Ground Squirrelsmentioning

confidence: 99%

“…Karels, unpublished data). These nonbreeders grow rapidly in spring and become indistinguishable, in terms of size, by summer (Lacey 1991, Buck andBarnes 1999a). Adult nonbreeding males (658.5 Ϯ 18.4 g, mean Ϯ 1 SE) were over 150 g heavier (F ϭ 30.2, df ϭ 2, 27, P Ͻ 0.0001) than adult breeding males (454.0 Ϯ 10.7 g) and juvenile males (493.5 Ϯ 26.8 g).…”

Section: Experimental Animalsmentioning

confidence: 99%

Reproduction at All Costs: The Adaptive Stress Response of Male Arctic Ground Squirrels

Boonstra

McColl

Karels

2001

Ecology

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Abstract. We tested the hypothesis that adult male arctic ground squirrels (Spermophilus parryii plesius) exhibit an adaptive stress response during the mating period that may compromise their survival, whereas males at other times (nonreproductive adult males and juvenile males) have a normal functional stress response. We assessed the physiological responsiveness of the stress axis, of energy mobilization, and of the immune response by subjecting adult breeding males, adult nonbreeding males, and juvenile males to a hormonal challenge and an immunocompetence challenge. At the onset of the breeding season in spring, only 25-30% of the population were males, and of those present during the mating period, half disappeared soon thereafter, and 82% were not replaced by immigrants. Adult breeding males had the highest levels of free cortisol, the lowest maximum corticosteroidbinding capacity, slight dexamethasone resistance, the lowest hematocrit, the lowest number of white blood cells, the highest number of eosinophils, and the poorest ability to respond to the foreign antigen challenge in comparison with the other two male classes. All of these characteristics were indicative of chronic stress in breeding males that may directly compromise their survival. Juvenile males in mid-August also showed many, but not all of these characteristics, indicative of a prolonged period of stress, presumably associated with the period of dispersal. Testosterone levels remained high irrespective of age or breeding condition, decreased when dexamethasone was injected, and increased when ACTH was injected. These latter results are unique in mammals. High testosterone levels and their augmentation with stressors may play a key role in maintenance of aggressive behavior. We conclude that breeding male arctic ground squirrels exhibit an adaptive stress response in which they trade off survival for reproduction. We hypothesize that similar stress responses may have evolved in other species with comparable life histories.

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“…Refuge use is common in all taxa and obligatory in many species since refugia often provide living, nesting, and socializing locations, protection from predation (Blumstein et al, 2001;Davis and Theimer, 2004;Martin and Lopez, 2000;Polis, 1980), and, perhaps most notably, a significant buffer from challenging environmental conditions including drought (Beck and Jennings, 2003;Bulova, 2002) and both high (Grant and Dunham, 1988;Rezende et al, 2003;Ricklefs and Hainsworth, 1968) and low (Buck and Barnes, 1999;Dorcas and Peterson, 1998;Peterson, 1987) air temperature extremes. These benefits become increasingly valuable in arid environments because aridity is often accompanied by challenging air temperatures making behaviors that benefit both water conservation and thermoregulation (e.g., shifting activity from diurnal to nocturnal, decreasing overall surface activity, hibernation/active-season dormancy) essential for survival.…”

Section: Introductionmentioning

confidence: 99%

An automated temperature-based option for estimating surface activity and refuge use patterns in free-ranging animals

Davis

Taylor

DeNardo

2008

Journal of Arid Environments

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Accurately assessing free ranging animals' patterns of surface activity and refuge use is critical, yet fundamentally challenging for biologists and wildlife managers. We evaluate the accuracy of an automated technique temperature based activity estimation (TBAE) in estimating surface activity and refuge use patterns of two sympatric reptiles, the western diamond backed rattlesnake (Crotalus atrox) and the Gila monster (Heloderma suspectum) in the Sonoran Desert. TBAE derived from a comparison of body temperature to shaded air temperature was effective in estimating the overall percent surface activity for both rattlesnakes (observed surface activity 51.8%, TBAE estimated surface activity 48.2%) and Gila monsters (observed 22.3%, TBAE 24.5%). There was, however, considerable interspecific difference in the effectiveness of TBAE in predicting surface activity at specific time points; TBAE was far more accurate for Gila monsters than for rattlesnakes (96% vs. 66% time point specific accuracy, respectively). We assert that, when validated, TBAE can be used to yield concurrent and accurate body temperatures and activity estimates for multiple free ranging animals, particularly in arid environments, which improves our understanding of animal biology and can be used to inform management decisions.

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Annual Cycle of Body Composition and Hibernation in Free-Living Arctic Ground Squirrels

Cited by 204 publications

References 30 publications

The timing of hibernation in Tasmanian echidnas: why do they do it when they do?1

The timing of hibernation in Tasmanian echidnas: why do they do it when they do?1

Reproduction at All Costs: The Adaptive Stress Response of Male Arctic Ground Squirrels

An automated temperature-based option for estimating surface activity and refuge use patterns in free-ranging animals

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