Corticosterone (CORT) is a glucocorticoid hormone that maintains energy balance and can modulate foraging behaviors in seabirds. However, CORT responses are not always predictable under similar biophysical conditions and do not necessarily influence the same behaviors across breeding stages and species. To enhance our understanding of CORT's role as a proximate determinant of foraging behavior and energy maintenance, we examined the relationships between body condition, CORT, foraging behavior, and foraging success between two sympatric breeding albatross species with differing foraging strategies and life histories, the Campbell albatross (Thalassarache impavida) and the gray-headed albatross (Thalassarache chrysostoma), from Campbell Island, New Zealand. Pre- and postforaging CORT did not differ between species or stage, potentially as a result of behavioral plasticity or different functional roles of CORT across stages. Unexpectedly, body condition did not correlate with preforaging CORT during incubation, although a negative correlation was observed in Campbell albatrosses during the guard stage. Furthermore, CORT mediated foraging success in both species and stages, but CORT mediated foraging behavior only in incubation-stage Campbell albatrosses that had shorter foraging ranges with higher pretrip CORT. Additionally, CORT positively correlated with mass gain and the time elapsed since the last feeding event in guard-stage albatrosses. Our results highlight the complexity of CORT in mediating energy balance in free-ranging animals. Our results also support that if CORT is to be usefully interpreted, breeding stage must be considered because the physiological and behavioral functionality of CORT may differ across stages, with enhanced sensitivity to energy reserves during chick rearing.

中文翻译：

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两种生活史不同的信天翁育种中皮质酮水平的变化：对身体状况的响应和觅食行为的驱动因素。

皮质酮（CORT）是一种糖皮质激素，可以维持能量平衡并可以调节海鸟的觅食行为。但是，CORT反应在相似的生物物理条件下并不总是可预测的，并且不一定会影响整个育种阶段和物种的相同行为。为了增进我们对CORT作为觅食行为和能量维持的决定因素的作用的理解，我们研究了两种不同觅食策略和生活史的同居繁殖信天翁物种之间的身体状况，CORT，觅食行为和觅食成功之间的关系。来自新西兰坎贝尔岛的信天翁（Thalassarache impavida）和灰头信天翁（Thalassarache chrysostoma）。物种或阶段之间，CORT的产前和产后无差异，可能是跨阶段行为可塑性或CORT的不同功能角色的结果。出乎意料的是，尽管在保护期坎贝尔信天翁中观察到负相关，但身体状况与孵化前的CORT无关。此外，CORT介导的物种和阶段的觅食成功，但CORT介导的觅食行为仅在孵化期的坎贝尔信天翁中具有更短的觅食范围和较高的绊前CORT。此外，CORT与质量增加和自保护阶段信天翁最后一次进食事件以来经过的时间呈正相关。我们的结果突出了CORT介导散养动物能量平衡的复杂性。我们的结果还支持，如果要对CORT进行有用的解释，