Metabolic Rate and Prehibernation Fattening in Free-Living Arctic Ground Squirrels

2013 ◽  
Vol 86 (5) ◽  
pp. 515-527 ◽  
Author(s):  
Michael J. Sheriff ◽  
Robert W. Fridinger ◽  
øivind Tøien ◽  
Brian M. Barnes ◽  
C. Loren Buck
Keyword(s):  
Metabolic Rate ◽  
Ground Squirrels ◽  
Free Living ◽  
Arctic Ground Squirrels

scholarly journals Interrelationships Among Timing of Hibernation, Reproduction, and Warming Soil in Free-Living Female Arctic Ground Squirrels

2012 ◽  
pp. 63-72 ◽  
Author(s):  
Cory T. Williams ◽  
Michael J. Sheriff ◽  
Franziska Kohl ◽  
Brian M. Barnes ◽  
C. Loren Buck
Keyword(s):  
Ground Squirrels ◽  
Free Living ◽  
Arctic Ground Squirrels

scholarly journals BODY TEMPERATURE AND ACTIVITY PATTERNS IN FREE-LIVING ARCTIC GROUND SQUIRRELS

2005 ◽  
Vol 86 (2) ◽  
pp. 314-322 ◽  
Author(s):  
Ryan A. Long ◽  
Timothy J. Martin ◽  
Brian M. Barnes
Keyword(s):  
Body Temperature ◽  
Activity Patterns ◽  
Ground Squirrels ◽  
Free Living ◽  
Arctic Ground Squirrels

Hibernation and Circadian Rhythms of Body Temperature in Free-Living Arctic Ground Squirrels

2012 ◽  
Vol 85 (4) ◽  
pp. 397-404 ◽  
Author(s):  
Cory T. Williams ◽  
Brian M. Barnes ◽  
Melanie Richter ◽  
C. Loren Buck
Keyword(s):  
Body Temperature ◽  
Circadian Rhythms ◽  
Ground Squirrels ◽  
Free Living ◽  
Arctic Ground Squirrels

scholarly journals Daily body temperature rhythms persist under the midnight sun but are absent during hibernation in free-living arctic ground squirrels

2011 ◽  
Vol 8 (1) ◽  
pp. 31-34 ◽  
Author(s):  
Cory T. Williams ◽  
Brian M. Barnes ◽  
C. Loren Buck
Keyword(s):  
Body Temperature ◽  
Circadian Rhythms ◽  
Ground Squirrels ◽  
The Arctic ◽  
Constant Light ◽  
Polar Regions ◽  
Free Living ◽  
Active Season ◽  
Temperature Rhythms ◽  
Arctic Ground Squirrels

In indigenous arctic reindeer and ptarmigan, circadian rhythms are not expressed during the constant light of summer or constant dark of winter, and it has been hypothesized that a seasonal absence of circadian rhythms is common to all vertebrate residents of polar regions. Here, we show that, while free-living arctic ground squirrels do not express circadian rhythms during the heterothermic and pre-emergent euthermic intervals of hibernation, they display entrained daily rhythms of body temperature ( T b ) throughout their active season, which includes six weeks of constant sun. In winter, ground squirrels are arrhythmic and regulate core body temperatures to within ±0.2°C for up to 18 days during steady-state torpor. In spring, after the use of torpor ends, male but not female ground squirrels, resume euthermic levels of T b in their dark burrows but remain arrhythmic for up to 27 days. However, once activity on the surface begins, both sexes exhibit robust 24 h cycles of body temperature. We suggest that persistence of nycthemeral rhythms through the polar summer enables ground squirrels to minimize thermoregulatory costs. However, the environmental cues (zeitgebers) used to entrain rhythms during the constant light of the arctic summer in these semi-fossorial rodents are unknown.

Plasticity and repeatability of activity patterns in free-living Arctic ground squirrels

2020 ◽  
Vol 169 ◽  
pp. 81-91
Author(s):  
Helen E. Chmura ◽  
Victor Y. Zhang ◽  
Sara M. Wilbur ◽  
Brian M. Barnes ◽  
C. Loren Buck ◽  
...  
Keyword(s):  
Activity Patterns ◽  
Ground Squirrels ◽  
Free Living ◽  
Arctic Ground Squirrels

scholarly journals Changing seasonality and phenological responses of free-living male arctic ground squirrels: the importance of sex

2013 ◽  
Vol 368 (1624) ◽  
pp. 20120480 ◽  
Author(s):  
Michael J. Sheriff ◽  
Melanie M. Richter ◽  
C. Loren Buck ◽  
Brian M. Barnes
Keyword(s):  
Snow Cover ◽  
Ground Squirrels ◽  
Free Living ◽  
Male And Female ◽  
Reproductive Maturation ◽  
Changing Patterns ◽  
Arctic Ground Squirrels ◽  
Northern Alaska ◽  
The Impact

Many studies have addressed the effects of climate change on species as a whole; however, few have examined the possibility of sex-specific differences. To understand better the impact that changing patterns of snow-cover have on an important resident Arctic mammal, we investigated the long-term (13 years) phenology of hibernating male arctic ground squirrels living at two nearby sites in northern Alaska that experience significantly different snow-cover regimes. Previously, we demonstrated that snow-cover influences the timing of phenological events in females. Our results here suggest that the end of heterothermy in males is influenced by soil temperature and an endogenous circannual clock, but timing of male emergence from hibernation is influenced by the timing of female emergence. Males at both sites, Atigun and Toolik, end heterothermy on the same date in spring, but remain in their burrows while undergoing reproductive maturation. However, at Atigun, where snowmelt and female emergence occur relatively early, males emerge 8 days earlier than those at Toolik, maintaining a 12-day period between male and female emergence found at each site, but reducing the pre-emergence euthermic period that is critical for reproductive maturation. This sensitivity in timing of male emergence to female emergence will need to be matched by phase shifts in the circannual clock and responsiveness to environmental factors that time the end of heterothermy, if synchrony in reproductive readiness between the sexes is to be preserved in a rapidly changing climate.

Thermoregulatory changes anticipate hibernation onset by 45 days: data from free-living arctic ground squirrels

2012 ◽  
Vol 182 (6) ◽  
pp. 841-847 ◽  
Author(s):  
Michael J. Sheriff ◽  
Cory T. Williams ◽  
G. J. Kenagy ◽  
C. Loren Buck ◽  
Brian M. Barnes
Keyword(s):  
Ground Squirrels ◽  
Free Living ◽  
Arctic Ground Squirrels
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