Extended incubation recesses in Sanderlings are impacted by temperature and body condition

Complex incubation strategies have evolved to solve the trade-off between parent survival and care for their eggs with often brief departures (recesses) that maximise egg survival or infrequent extended recesses maximising adult condition. Here we examined incubation behaviour of Sanderlings (Calidris alba), a species that exhibits both bi- and uniparental incubation behaviour. During 11 breeding seasons in Greenland, we have quantified incubation variability with thermologgers placed in nests. We estimated the impact of environmental conditions and individual characteristics on the occurrence and the duration of recesses. We found that extended recesses are a unique feature of uniparentals, and their frequency and duration increased in colder temperatures. The relationship was mediated by body condition, with individuals in poor condition performing longer extended recesses in colder temperatures. This suggests that extended recesses may represent a shift towards self-maintenance at the expense of the egg care, allowing birds to continue incubating under unfavourable conditions. Our study illustrates how extended recesses may be a key breeding strategy to overcome high energetical costs associated with incubation. Quantifying such behavioural flexibility paves the way for tracking future behavioural responses of individuals in the face of changing environments.为解决亲鸟存活与卵抚育之间的权衡难题，鸟类演化出了复杂的孵卵策略：通过两类离巢暂歇（recesses）行为——频次较高的短暂离巢以最大化卵的存活率，或是频次较低的长时间离巢以优化成体身体状态。本研究以兼具双亲孵育与单亲孵育行为的三趾鹬（Sanderling，Calidris alba）为研究对象，探究其孵卵行为模式。我们在格陵兰开展了11个繁殖季的野外研究，通过放置于巢内的温度记录仪（thermologgers）量化了孵卵行为的变异特征。我们分析了环境条件与个体特征对离巢暂歇的发生概率与持续时长的影响。研究发现，长时间离巢暂歇是单亲孵育个体的独有行为特征，且其发生频率与持续时长会随环境温度降低而显著增加。上述关系受到个体身体状态的介导：身体状况较差的个体在低温环境下会开展时长更长的长时间离巢暂歇。这表明，长时间离巢暂歇或许代表亲鸟以牺牲卵的抚育为代价转向自我维护，从而使鸟类能够在不利环境中持续开展孵卵行为。本研究阐明了长时间离巢暂歇作为核心繁殖策略，如何帮助鸟类克服孵卵过程中产生的高能量成本。对这类行为灵活性的量化研究，为预测气候变化背景下鸟类个体未来的行为响应铺平了道路。