Data from: Daily activity is repeatable but varies across the breeding season in female great tits

Wild animals typically organize activity around a 24-hour day and daily
timing across the year is optimized for both survival and reproductive
success. Among-individual variation in chronotype, when individuals begin
or end their active day relative to a cue such as photoperiod, often
exists within a population. Both intrinsic and extrinsic factors
contribute to this variation and activity patterns may change across and
within different life history stages as energetic investment changes. Here
we describe population level changes in female great tit (Parus major)
activity patterns of onset and offset of activity as well as assess
variation and repeatability in daily activity both within- and
across-breeding stages. We fitted individuals with accelerometers to track
activity prior to nest building through chick rearing. Prior to clutch
initiation females began their active day before sunrise, however in the
days prior to laying their first egg, activity was delayed until after
sunrise. Females ended activity prior to sunset across the monitoring
period and earliest during egg laying and incubation. Additionally,
females exhibited greater among- and within-individual variance in
chronotype during parental care. Individual female daily activity was
moderately repeatable within breeding stages and strongly covaried across
several breeding stages. These findings expand our understanding of
individual variation in chronotype during reproduction and the potential
fitness implications of chronotype in wild animals.

野生动物的活动通常以24小时为周期，全年的每日活动时序均以优化生存与繁殖成功率为目标。种群内部往往存在个体间的活动节律型（chronotype）差异，即个体相对于光周期等环境线索开启或结束其活跃时段的时机各不相同。这种差异受内在与外在因素共同影响，且随着能量投入的变化，活动模式在不同生活史阶段之间及阶段内部均可能发生改变。本研究描述了雌性大山雀（Parus major）从筑巢前到育雏阶段的活动起始与结束时机的种群水平变化，并评估了每日活动在各繁殖阶段内以及跨繁殖阶段的变异与可重复性。我们为个体佩戴加速度计（accelerometers）以追踪其活动，监测时段覆盖筑巢前直至育雏阶段。在产卵启动前，雌性的活跃时段始于日出之前，但在产下首枚卵前的数日，活动延迟至日出之后。整个监测周期内，雌性均于日落前结束活动，其中以产卵期与孵卵期结束活动的时间最早。此外，亲本抚育阶段内，雌性的活动节律型在个体间及个体内的变异程度更高。雌性个体的每日活动在各繁殖阶段内呈现中等程度的可重复性，且在多个繁殖阶段间存在显著的协同变化。本研究结果拓展了我们对繁殖期间个体活动节律型变异的认知，以及野生动物活动节律型对适合度的潜在影响。