Timing of activity can reveal an organism's efforts to optimize foraging either by minimizing energy loss through passive movement or by maximizing energetic gain through foraging. Here, we assess whether signals of either of these strategies are detectable in the timing of activity of daily, local movements by birds. We compare the similarities of timing of movement activity among species using six temporal variables: start of activity relative to sunrise, end of activity relative to sunset, relative speed at midday, number of movement bouts, bout duration and proportion of active daytime hours. We test for the influence of flight mode and foraging habitat on the timing of movement activity across avian guilds. We used 64 570 days of GPS movement data collected between 2002 and 2019 for local (non‐migratory) movements of 991 birds from 49 species, representing 14 orders. Dissimilarity among daily activity patterns was best explained by flight mode. Terrestrial soaring birds began activity later and stopped activity earlier than pelagic soaring or flapping birds. Broad‐scale foraging habitat explained less of the clustering patterns because of divergent timing of active periods of pelagic surface and diving foragers. Among pelagic birds, surface foragers were active throughout all 24 hrs of the day while diving foragers matched their active hours more closely to daylight hours. Pelagic surface foragers also had the greatest daily foraging distances, which was consistent with their daytime activity patterns. This study demonstrates that flight mode and foraging habitat influence temporal patterns of daily movement activity of birds.

中文翻译：

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鸟类非迁徙运动的昼夜定时：觅食空间尺度的重要性

活动的时机可以揭示生物体通过减少被动运动造成的能量损失或通过觅食获得最大能量获取来优化觅食的努力。在这里，我们评估在鸟类每日局部活动的活动时间中是否可以检测到这两种策略中的任何一种的信号。我们使用六个时间变量比较物种间运动活动时间的相似性：相对于日出的活动开始，相对于日落的活动结束，中午的相对速度，运动次数，运动时间和白天活动时间的比例。我们测试飞行模式和觅食栖息地对跨鸟类行会运动活动时间的影响。我们使用2002年至2019年收集的64570天的GPS运动数据来进行49种鸟类991羽的本地（非迁徙）运动，代表14个订单。日常活动模式之间的差异最好通过飞行模式来解释。陆上高飞鸟类比中上层高飞或拍打鸟类晚些时候开始活动，而停止活动则早些。广泛的觅食栖息地解释了较少的聚类模式，因为中上层地表和潜水觅食者活跃期的时间不一致。在中上层鸟类中，表面觅食者在一天的所有24小时都活跃，而潜水觅食者的活跃时间更接近白天。中上层地表觅食者的每日觅食距离也最大，这与他们的白天活动模式一致。