Balancing time allocation among competing behaviours is an essential part of energy management for all animals. However, trade-offs in time allocation may vary according to the sex of the individual, their age, and even underlying physiology. During reproduction, higher energetic demands and constrained internal resources place greater demand on optimizing these trade-offs insofar that small adjustments in time-activity may lead to substantial effects on an individual’s limited energy budget. The most extreme case is found in animals that undergo capital breeding, where individuals fast for the duration of each reproductive episode. We investigated potential underlying drivers of time-activity and describe aspects of trade-offs in time-activity in a wild, capital breeding pinniped, the grey seal Halichoerus grypus, during the lactation period. For the first time, we were able to access full 24-h activity budgets across the core duration of lactation as well as characterize how aspects of stress-coping styles influence time allocation through the use of animal-borne accelerometers and heart rate monitors in situ. We found that there was a distinct trade-off in time activity between time spent Resting and Alert (vigilance). This trade-off varied with the pup’s development, date, and maternal stress-coping style as indicated by a measure of heart rate variability, rMSSD. In contrast, time spent Presenting/Nursing did not vary across the duration of lactation given the variables tested. We suggest that while mothers balance time spent conserving resources (Resting) against time expending energy (Alert), they are also influenced by the inherent physiological drivers of stress-coping styles. How animals apportion their time among different behaviours is key to their success. These trade-offs should be finely balanced to avoid unnecessary energy expenditure. Here, we examine how grey seal mothers balance their activity patterns during the short, but energetically demanding, period of pup-rearing. Animal-borne accelerometers provided a uniquely detailed and continuous record of activity during pup-rearing for 38 mothers. We also used heart rate monitors to provide measures of each individual’s stress-coping style. We found that mothers balance time Resting against remaining Alert while time Presenting/Nursing was largely independent of all factors measured. Stress-coping styles were found to drive the balancing and variation of all behaviours. This novel indication that differences in personality-like traits may drive whole activity budgets should be considered when assessing trade-offs in time allocation across a much wider variety of species.

中文翻译：

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资本饲养者的应对方式在时间分配中调节行为权衡：使用加速度计和心率变异性评估哺乳期灰海豹（Halichoerus grypus）的精细活动预算

在竞争行为之间平衡时间分配是所有动物能量管理的重要组成部分。然而，时间分配的权衡可能会根据个人的性别、年龄甚至潜在的生理机能而有所不同。在繁殖期间，更高的能量需求和受限的内部资源对优化这些权衡提出了更高的要求，因为时间活动的微小调整可能会对个人有限的能量预算产生重大影响。最极端的情况是在经历资本繁殖的动物中发现的，在这种情况下，个体在每次繁殖期间都会禁食。我们调查了时间活动的潜在潜在驱动因素，并描述了哺乳期野生、资本繁殖的鳍足类灰海豹 Halichoerus grypus 的时间活动权衡的各个方面。我们第一次能够获得整个泌乳核心持续时间的完整 24 小时活动预算，并通过使用动物加速度计和原位心率监测器来表征压力应对方式的各个方面如何影响时间分配. 我们发现在休息时间和警觉（警惕）时间之间存在明显的时间活动权衡。这种权衡因幼犬的发育、日期和母体压力应对方式而异，如心率变异性测量值 rMSSD 所示。相比之下，考虑到测试的变量，在整个哺乳期中花费的展示/护理时间没有变化。我们建议，虽然母亲在节省资源（休息）和消耗精力（警报）的时间之间取得平衡，但她们也受到压力应对方式的内在生理驱动因素的影响。动物如何在不同的行为中分配时间是它们成功的关键。这些权衡应该很好地平衡，以避免不必要的能量消耗。在这里，我们研究了灰海豹母亲如何在短暂但精力充沛的幼崽饲养期间平衡其活动模式。动物性加速度计为 38 位母亲在幼崽饲养期间提供了独特的详细和连续的活动记录。我们还使用心率监测器来衡量每个人的压力应对方式。我们发现，母亲平衡休息时间与剩余警觉时间，而呈现/护理时间在很大程度上独立于所有测量的因素。发现压力应对方式可以推动所有行为的平衡和变化。