Social interactions can shape daily activity patterns, and this is an area of growing research interest. The propensity for individuals to be active at certain times of day may structure interactions with competitors and potential mates, influencing fitness outcomes. Aspects of daily activity such as timing of activity onset and offset exhibit within-individual repeatability, which raises the possibility that they may be subject to natural and sexual selection. This study used a biologging approach in free-living Arctic ground squirrels, Urocitellus parryii, to test the hypothesis that interactions between the sexes shape temporal patterns of daily activity. We predicted that males would become active earlier than females during the mating period, consistent with sexual selection on activity timing. We also examined repeatability in activity timing and how repeatability estimates are affected by sampling methodology. We deployed collar-mounted light loggers on ground squirrels and used timing of light transitions to determine daily onset and offset of above-ground activity. We observed 87 animals over 3 years, collecting over 7500 observations of daily activity. We found that daily activity timing had moderate (onset) to low (offset) adjusted repeatability. The difference in daily activity timing between the sexes varied seasonally: males remained active later than females during mating, while females initiated activity earlier and extended activity later during lactation. Adjusted repeatability estimates were sensitive to sampling methodology: they varied seasonally and declined with increased behavioural sampling. These results suggest that offset, not onset, may be shaped by sexual selection and that life history differences shape sex-dependent activity patterns in ground squirrels. We propose that activity onset may be under more strict circadian control than offset. This study suggests that researchers must consider seasonality and sampling design when estimating behavioural repeatability. Biologging could transform studies of individual variation by enabling high-frequency sampling of free-living animals.

中文翻译：

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自由生活的北极地松鼠活动模式的可塑性和可重复性

社交互动可以塑造日常活动模式，这是一个日益引起研究兴趣的领域。个人在一天中的某些时间活跃的倾向可能会影响与竞争对手和潜在伴侣的互动，从而影响健康结果。日常活动的各个方面，例如活动开始和抵消的时间，表现出个体内部的可重复性，这增加了它们可能受到自然选择和性选择的可能性。这项研究在自由生活的北极地松鼠 Urocitellus parryii 中使用了一种生物记录方法，以检验两性之间的相互作用塑造了日常活动的时间模式的假设。我们预测，在交配期间，雄性会比雌性更早活跃，这与活动时间的性选择一致。我们还研究了活动时间安排的可重复性以及重复性估计如何受抽样方法的影响。我们在地松鼠身上部署了安装在衣领上的光记录器，并使用光转换的时间来确定地面活动的每日开始和偏移。我们在 3 年内观察了 87 只动物，收集了超过 7500 条日常活动的观察结果。我们发现日常活动时间具有中等（开始）到低（偏移）调整的可重复性。两性之间日常活动时间的差异随季节而变化：在交配期间，雄性比雌性保持活跃的时间晚，而雌性在哺乳期间开始活动更早，活动时间延长。调整后的重复性估计对抽样方法很敏感：它们随季节变化，并随着行为抽样的增加而下降。这些结果表明，抵消，而不是开始，可能是由性选择决定的，生活史的差异塑造了地松鼠的性别依赖活动模式。我们建议活动开始可能受到比抵消更严格的昼夜节律控制。这项研究表明，研究人员在估计行为可重复性时必须考虑季节性和抽样设计。生物记录可以通过对自由生活的动物进行高频采样来改变个体变异的研究。这项研究表明，研究人员在估计行为可重复性时必须考虑季节性和抽样设计。生物记录可以通过对自由生活的动物进行高频采样来改变个体变异的研究。这项研究表明，研究人员在估计行为可重复性时必须考虑季节性和抽样设计。生物记录可以通过对自由生活的动物进行高频采样来改变个体变异的研究。