Meeting Abstract
Little is known of the relationship between glucocorticoids and specific behavioral outcomes in free-living mammals. In this study, we used collars affixed with accelerometers and light loggers to measure the above-ground overall dynamic body acceleration (ODBA), an index of activity-specific energy expenditure, across the active season on free-living artic ground squirrels ( Urocitellus parryii ). In addition, we measured fecal cortisol metabolites (FCM) to non-invasively assess adrenocortical activity of squirrels across their active season. Female FCM concentrations were highest during the mid-lactation interval and lowest during post lactation, while male FCM did not vary across the active season. Overall, males had higher baseline FCM levels than females across the year (male LS-mean = 6.2, SE = 0.10; female LS-mean=5.7, SE=0.08). Levels of above-ground activity were consistent with expectations of reproductive demand; activity levels of males were higher than females during the mating period and lower than in females during the mid-lactation period. Cold and wet weather, which is known to adversely affect conditions of thermal exchange, increased FCM and decreased above ground activity levels in both sexes. The effect of weather on FCM concentrations was greatest in the early season, possibly due to reduced forage availability associated with early springtime in the Arctic. Lastly, our results suggest that a negative relationship between FCM concentrations and intensity of above-ground activity exists for female but not male, arctic ground squirrels. Collectively, this study furthers our understanding of how reproductive state and environmental conditions may interact to affect behavioral patterns and adrenocortical activity in free-living mammals.
