Seasonal patterns and sexual differences in the feeding ecology of arctic ground squirrels (Spermophilus parryii plesius)

1985 ◽  
Vol 63 (6) ◽  
pp. 1298-1301 ◽  
Author(s):  
Ian G. McLean
Keyword(s):  
Feeding Ecology ◽  
Ground Squirrels ◽  
Sexual Differences ◽  
Seasonal Patterns ◽  
Spermophilus Parryii ◽  
Feeding Sites ◽  
Arctic Ground Squirrels ◽  
Selection Of

Arctic ground squirrels (Spermophilus parryii plesius) were studied in southwestern Yukon during the summers of 1977, 1978, and 1979. Samples of feces were collected from every adult captured every 2 weeks in 1978. Legumes were predominant in the diet until the fall, when squirrels switched to Artemisia. Females switched to Artemisia 1 month earlier than males, which correlates with the females' earlier entry into hibernation. Low abundance of legumes in areas in which squirrels preferred to feed indicated that squirrels fed selectively, although proximity of burrows also influenced selection of feeding sites.

scholarly journals Habitat selection by arctic ground squirrels (Spermophilus parryii)

2010 ◽  
Vol 91 (5) ◽  
pp. 1251-1260 ◽  
Author(s):  
Oliver E. Barker ◽  
Andrew E. Derocher
Keyword(s):  
Habitat Selection ◽  
Ground Squirrels ◽  
Spermophilus Parryii ◽  
Arctic Ground Squirrels

scholarly journals Ascorbate dynamics and oxygen consumption during arousal from hibernation in Arctic ground squirrels

2001 ◽  
Vol 281 (2) ◽  
pp. R572-R583 ◽  
Author(s):  
Ø. Tøien ◽  
K. L. Drew ◽  
M. L. Chao ◽  
M. E. Rice
Keyword(s):  
Peak Plasma ◽  
Plasma Concentrations ◽  
Metabolic Stress ◽  
Ground Squirrels ◽  
Electromyographic Activity ◽  
Spermophilus Parryii ◽  
Plasma Ascorbate ◽  
Leukocyte Counts ◽  
Plasma Urate ◽  
Arctic Ground Squirrels

During hibernation in Arctic ground squirrels ( Spermophilus parryii), O2 consumption and plasma leukocyte counts decrease by >90%, whereas plasma concentrations of the antioxidant ascorbate increase fourfold. During rewarming, O2 consumption increases profoundly and plasma ascorbate and leukocyte counts return to normal. Here we investigated the dynamic interrelationships among these changes. Plasma ascorbate and uric acid (urate) concentrations were determined by HPLC from blood samples collected at ∼15-min intervals via arterial catheter; leukocyte count and hematocrit were also determined. Body temperature, O2 consumption, and electromyographic activity were recorded continuously. Ascorbate, urate, and glutathione contents in body and brain samples were determined during hibernation and after arousal. During rewarming, the maximum rate of plasma ascorbate decrease occurred at the time of peak O2 consumption and peak plasma urate production. The ascorbate decrease did not correlate with mouth or abdominal temperature; uptake into leukocytes could account for only a small percentage. By contrast, liver and spleen ascorbate levels increased significantly after arousal, which could more than account for ascorbate clearance from plasma. Brain ascorbate levels remained constant. These data suggest that elevated concentrations of ascorbate {[Asc]} in plasma {[Asc]p} provide an antioxidant source that is redistributed to tissues during the metabolic stress that accompanies arousal.

Effects of food and predators on the home-range sizes of Arctic ground squirrel (Spermophilus parryii)

1998 ◽  
Vol 76 (3) ◽  
pp. 592-596 ◽  
Author(s):  
Anne H Hubbs ◽  
Rudy Boonstra
Keyword(s):  
Home Range ◽  
Ground Squirrel ◽  
Large Scale ◽  
Yukon Territory ◽  
Ground Squirrels ◽  
Home Ranges ◽  
Spermophilus Parryii ◽  
Mammalian Predators ◽  
Core Areas ◽  
Arctic Ground Squirrels

We used radiotelemetry to study the effects of food addition and predator reduction on the home-range sizes of adult Arctic ground squirrels (Spermophilus parryii) on large-scale experimental grids in the boreal forest of the southwestern Yukon Territory. Home ranges were 2-7 times smaller on food-supplemented grids than on nonsupplemented grids, regardless of whether large mammalian predators were present. Similarly, core areas (where 50% of activities occur) were 8-11 times smaller on food-supplemented grids. Food availability rather than predator presence primarily determined the sizes of home ranges and core areas of Arctic ground squirrels.

The influence of herbivores and neighboring plants on risk of browsing: a case study using arctic lupine (Lupinus arcticus) and arctic ground squirrels (Spermophilus parryii plesius)

2001 ◽  
Vol 79 (5) ◽  
pp. 874-880 ◽  
Author(s):  
Leonardo Frid ◽  
Roy Turkington
Keyword(s):  
Plant Density ◽  
Plant Morphology ◽  
Ground Squirrels ◽  
Individual Plant ◽  
Resource Concentration ◽  
Spermophilus Parryii ◽  
Increased Risk ◽  
Arctic Ground Squirrels ◽  
A Site ◽  
Palatable Species

We examined how herbivore distribution and density, neighboring plant density and species composition, and individual plant morphology all influence the risk that individual arctic lupines (Lupinus arcticus) will be browsed by arctic ground squirrels (Spermophilus parryii plesius). Risk of being browsed was significantly influenced by the number of resident ground squirrels but not by overall squirrel density at a site. As the leaf density of neighboring conspecifics increased, risk of browsing to an individual lupine decreased except when palatable neighbors were also present. The presence of other palatable species increased the risk of browsing. Risk was highest when both lupine and other palatable neighbors were present. The presence of unpalatable neighbors reduced the risk of browsing of individual lupines. We discuss these results in the context of three hypotheses: (1) attractant decoy, (2) resource concentration, and (3) repellent plant. No single hypothesis accounts for our observations, but an interaction between herbivores, neighbors, and individual lupine morphology determined risk of browsing.

scholarly journals Insular arctic ground squirrels (Spermophilus parryii) of the North Pacific: indigenous or exotic?

2010 ◽  
Vol 91 (6) ◽  
pp. 1401-1412 ◽  
Author(s):  
Joseph A. Cook ◽  
Aren A. Eddingsaas ◽  
Janet L. Loxterman ◽  
Steve Ebbert ◽  
S. O. MacDonald
Keyword(s):  
North Pacific ◽  
Ground Squirrels ◽  
Spermophilus Parryii ◽  
The North ◽  
Arctic Ground Squirrels ◽  
The North Pacific

scholarly journals Arctic ground squirrel predation on collared lemmings

1990 ◽  
Vol 68 (4) ◽  
pp. 757-760 ◽  
Author(s):  
Rudy Boonstra ◽  
Charles J. Krebs ◽  
Michelle Kanter
Keyword(s):  
Northwest Territories ◽  
Ground Squirrel ◽  
Ground Squirrels ◽  
Intensive Study ◽  
Arctic Ground Squirrel ◽  
Spermophilus Parryii ◽  
Arctic Ground Squirrels

We document the first recorded evidence of predation of collared lemmings (Dicrostonyx kilangmiutak) by arctic ground squirrels (Spermophilus parryii). During an intensive study of lemming populations at Pearce Point, Northwest Territories, using livetrapping and radiotelemetry, we found one and six lemmings predated by arctic ground squirrels in 1987 and 1988, respectively. Predation involved some or all of the following: digging lemmings out of burrows, carrying them to temporary ground squirrel burrows, and partial or complete consumption. The best evidence was obtained during 1988, when a minimum of 4.5% (6/132) of radiotagged lemmings were killed by squirrels.

scholarly journals mRNA Stability and Polysome Loss in Hibernating Arctic Ground Squirrels (Spermophilus parryii)

2000 ◽  
Vol 20 (17) ◽  
pp. 6374-6379 ◽  
Author(s):  
Jason E. Knight ◽  
Erin Nicol Narus ◽  
Sandra L. Martin ◽  
Allan Jacobson ◽  
Brian M. Barnes ◽  
...  
Keyword(s):  
Mrna Stability ◽  
Functional Significance ◽  
Binding Protein ◽  
Ground Squirrels ◽  
Gene Products ◽  
Body Temperatures ◽  
Spermophilus Parryii ◽  
Torpor Bout ◽  
Arctic Ground Squirrels ◽  
The Stability

ABSTRACT All small mammalian hibernators periodically rewarm from torpor to high, euthermic body temperatures for brief intervals throughout the hibernating season. The functional significance of these arousal episodes is unknown, but one suggestion is that rewarming may be related to replacement of gene products lost during torpor due to degradation of mRNA. To assess the stability of mRNA as a function of the hibernation state, we examined the poly(A) tail lengths of liver mRNA from arctic ground squirrels sacrificed during four hibernation states (early and late during a torpor bout and early and late following arousal from torpor) and from active ground squirrels sacrificed in the summer. Poly(A) tail lengths were not altered during torpor, suggesting either that mRNA is stabilized or that transcription continues during torpor. In mRNA isolated from torpid ground squirrels, we observed a pattern of 12 poly(A) residues at greater densities approximately every 27 nucleotides along the poly(A) tail, which is a pattern consistent with binding of poly(A)-binding protein. The intensity of this pattern was significantly reduced following arousal from torpor and undetectable in mRNA obtained from summer ground squirrels. Analyses of polysome profiles revealed a significant reduction in polyribosomes in torpid animals, indicating that translation is depressed during torpor.

Absence of cellular stress in brain after hypoxia induced by arousal from hibernation in Arctic ground squirrels

2005 ◽  
Vol 289 (5) ◽  
pp. R1297-R1306 ◽  
Author(s):  
Yi Long Ma ◽  
Xiongwei Zhu ◽  
Patricia M. Rivera ◽  
Øivind Tøien ◽  
Brian M. Barnes ◽  
...  
Keyword(s):  
Physiological Stress ◽  
Cellular Stress ◽  
Hypoxia Inducible Factor ◽  
Blood Gases ◽  
Ground Squirrels ◽  
Oxidative Modification ◽  
Hypoxia Tolerance ◽  
Metabolic Demand ◽  
Spermophilus Parryii ◽  
Arctic Ground Squirrels

Although hypoxia tolerance in heterothermic mammals is well established, it is unclear whether the adaptive significance stems from hypoxia or other cellular challenge associated with euthermy, hibernation, or arousal. In the present study, blood gases, hemoglobin O2 saturation (So2), and indexes of cellular and physiological stress were measured during hibernation and euthermy and after arousal thermogenesis. Results show that arterial O2 tension (PaO2) and So2 are severely diminished during arousal and that hypoxia-inducible factor (HIF)-1α accumulates in brain. Despite evidence of hypoxia, neither cellular nor oxidative stress, as indicated by inducible nitric oxide synthase (iNOS) levels and oxidative modification of biomolecules, was observed during late arousal from hibernation. Compared with rats, hibernating Arctic ground squirrels ( Spermophilus parryii) are well oxygenated with no evidence of cellular stress, inflammatory response, neuronal pathology, or oxidative modification following the period of high metabolic demand necessary for arousal. In contrast, euthermic Arctic ground squirrels experience mild, chronic hypoxia with low So2 and accumulation of HIF-1α and iNOS and demonstrate the greatest degree of cellular stress in brain. These results suggest that Arctic ground squirrels experience and tolerate endogenous hypoxia during euthermy and arousal.

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