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|Title: ||Seasonal changes in glucocorticoid and testosterone concentrations in free-living arctic ground squirrels from the boreal forest of the Yukon|
|Authors: ||Boonstra, Rudy|
Hubbs, Anne H.
Lacey, Eileen A.
McColl, Carolyn J.
|Issue Date: ||2001|
|Publisher: ||NRC Canada|
|Citation: ||Can. J. Zool. 79: 49–58 (2001)|
|Abstract: ||We examined how glucocorticoid and testosterone concentrations changed from spring to summer by
livetrapping free-living populations of arctic ground squirrels (Spermophilus parryii). The primary glucocorticoid was
found to be cortisol, with corticosterone below measurable concentrations in most individuals. Livetrapping elicited a
strong stress response in both sexes: breeding males and females trapped in spring had free cortisol concentrations 4
and 34 times, respectively, those of base-line animals. The maximum corticosteroid-binding capacity (MCBC) was unaffected
by trapping and was about 3 times higher in breeding females than in breeding males. Over the active season,
MCBC values were lowest in all male classes (juveniles, nonreproductive adults, and reproductive adults), being less
than half those in all female classes; pregnant females had values approximately twice those of juvenile females. However,
free cortisol concentrations were similar in all female classes and in juvenile males and about half those in adult
males. Livetrapping increased testosterone concentrations in males over those found in samples from base-line males,
and testosterone concentrations did not affect MCBC values. Testosterone concentrations in livetrapped animals differed
significantly among male classes, with nonreproductive males maintaining concentrations 64% of those in breeding
males and 10 times those in juveniles.|
|Appears in Collections:||Biology|
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