Corticosterone is the primary metabolic steroid in birds and is vital for maintaining homeostasis. However, the relationship between baseline corticosterone and reproduction is unclear, and we lack an understanding of how differences in baseline corticosterone at one stage of the breeding cycle influence reproductive effort at later stages. In a wild population of house wrens, we quantified the concentration of corticosterone in yolks of freshly laid eggs as an integrated measure of maternal physiology and related this to a behavioral measure of stress reactivity made during the nestling period, namely, the latency with which females resumed parental activities following a standardized disturbance at their nest (setting up a camera to record provisioning). Females that recently produced eggs containing higher corticosterone concentrations, which were significantly repeatable within females, took longer to resume activity related to parental care (i.e., feeding and brooding young) following the disturbance. Moreover, a female's latency to resume parental activities negatively predicted her provisioning of nestlings with food and the condition of these young at fledging but did not predict the number fledged. We cross-fostered offspring prior to hatching so these effects on maternal behavior are independent of any prenatal maternal effects on nestlings via the egg. These results are consistent with earlier findings, suggesting that females with higher baseline corticosterone during egg laying or early incubation tend to prioritize self-maintenance over reproduction compared with females with lower baseline corticosterone and suggest that a female's latency to return to her nest and resume parental care following a disturbance might represent a simple, functional measure of maternal stress reactivity.

中文翻译：

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孵化后的父母照料和后代的生长随母鸟皮质酮水平的变化而变化。

皮质酮是鸟类中的主要代谢类固醇，对于维持体内稳态至关重要。但是，基线皮质酮和生殖之间的关系尚不清楚，我们还不了解在繁殖周期的一个阶段基线皮质酮的差异如何影响后期阶段的生殖力。在a的野生种群中，我们量化了刚产蛋卵黄中的皮质酮浓度，作为母体生理的一项综合指标，并将其与在雏鸟期进行的应激反应的行为指标（即雌性的潜伏期）联系起来。在巢中发生标准化骚扰后恢复了父母活动（安装了摄像头以记录供应情况）。最近产卵的皮质激素浓度更高的雌性，这些疾病在女性中具有明显的可重复性，并且在干扰后需要更长的时间才能恢复与父母照料有关的活动（即喂养和育雏）。此外，女性恢复父母活动的潜伏期负面地预示着她给雏鸟提供食物以及这些年轻人在出雏时的状况，但并没有预测出雏鸟的数量。我们在孵化之前对后代进行交叉育种，因此这些对产妇行为的影响独立于产前产妇对通过卵对雏鸟的影响。这些结果与较早的发现是一致的，这表明与基线皮质酮较低的雌性相比，在产卵或早期孵化期间基线皮质酮较高的雌性倾向于将自我维持优先于生殖。