The dynamic relationship between glucocorticoids and behavior are not well understood in wild mammals. We investigated how weather, body condition, and reproduction interact to affect cortisol levels and activity patterns in a free-living population of arctic ground squirrels (Urocitellus parryii). As a proxy for foraging and escape behaviors, collar-mounted accelerometers and light loggers were used to measure above-ground activity levels and the amount of time squirrels spent below the surface, respectively. Fecal cortisol metabolites (FCMs) were quantified to assess glucocorticoid secretion in squirrels. Male and female squirrels differed in above-ground activity levels and time spent below-ground across the active season, with males being most active during mating and females most active during lactation. We also found that female, but not male, squirrels exhibited seasonal variation in FCM levels, with concentrations highest during mid-lactation and lowest after the lactation period. In female squirrels, the seasonal relationships between breeding stage, activity, and FCM levels were also consistent with changes in maternal investment and the preparative role that glucocorticoids are hypothesized to play in energy mobilization. Body condition was not associated with FCM levels in squirrels. As predicted, deteriorating weather also influenced FCM levels and activity patterns in squirrels. FCM concentrations were affected by an interaction between temperature and wind speed when seasonal temperatures were lowest. In addition, above-ground activity, but not time spent below-ground, positively correlated with FCM levels. These results suggest that, although ground squirrels avoid inclement weather by remaining below-ground, activation of the stress axis may stimulate foraging activity.

在野生哺乳动物中，糖皮质激素与行为之间的动态关系尚不十分清楚。我们调查了天气，身体状况和繁殖如何相互作用以影响北极松鼠（Urocitellus parryii）自由生活种群中的皮质醇水平和活动模式）。作为觅食和逃避行为的替代指标，安装在衣领上的加速度计和光记录仪分别用于测量地面活动水平和松鼠在地面下所花费的时间。粪便中的皮质醇代谢产物（FCMs）进行定量，以评估松鼠中糖皮质激素的分泌。整个活动季节，雄性和雌性松鼠的地面活动水平和在地下的时间不同，雄性在交配期间最活跃，雌性在哺乳期间最活跃。我们还发现，雌性而不是雄性的松鼠表现出FCM水平的季节性变化，其浓度在哺乳中期最高，而在泌乳期最低。在雌性松鼠中，繁殖阶段，活动，FCM水平和FCM水平也与孕产妇投资的变化以及糖皮质激素在能量动员中的准备作用相一致。身体状况与松鼠的FCM水平无关。正如预测的那样，恶劣的天气也影响了松鼠的FCM水平和活动模式。当季节性温度最低时，FCM浓度受温度和风速之间相互作用的影响。此外，地上活动而不是地下活动所花费的时间与FCM水平成正相关。这些结果表明，尽管地松鼠通过保持在地下避免了恶劣的天气，但是应力轴的激活可能会刺激觅食活动。身体状况与松鼠的FCM水平无关。正如预测的那样，恶劣的天气也影响了松鼠的FCM水平和活动模式。当季节性温度最低时，FCM浓度受温度和风速之间相互作用的影响。此外，地上活动而不是地下活动所花费的时间与FCM水平成正相关。这些结果表明，尽管地松鼠通过保持在地下避免了恶劣的天气，但是应力轴的激活可能会刺激觅食活动。身体状况与松鼠的FCM水平无关。如预测的那样，恶劣的天气也影响了松鼠的FCM水平和活动模式。当季节性温度最低时，FCM浓度受温度和风速之间相互作用的影响。此外，地上活动而不是地下活动所花费的时间与FCM水平成正相关。这些结果表明，尽管地松鼠通过保持在地下避免了恶劣的天气，但是应力轴的激活可能会刺激觅食活动。而不是花费在地下的时间，与FCM水平呈正相关。这些结果表明，尽管地松鼠通过保持在地下避免了恶劣的天气，但是应力轴的激活可能会刺激觅食活动。而不是花费在地下的时间，与FCM水平呈正相关。这些结果表明，尽管地松鼠通过保持在地下避免了恶劣的天气，但是应力轴的激活可能会刺激觅食活动。