Loshchagina Julia, Naidenko Sergey, Tsvey Arseny
Institute of Geography RAS, Staromonetny per. 29, Moscow 119017, Russia.
Severtsov Institute of Ecology and Evolution RAS, Leninsky Ave. 33, Moscow 119071, Russia.
Horm Behav. 2025 Jul;173:105764. doi: 10.1016/j.yhbeh.2025.105764. Epub 2025 May 27.
During migration, birds must repeatedly decide when to terminate stopover and resume migratory flight. Such decisions greatly affect their overall migration success and, ultimately, fitness. Departure probability increases with higher levels of energy reserves, positive wind support and progression of the migration season. However, our knowledge of the endocrine mechanisms underlying this process is still incomplete. To evaluate the possible role of baseline corticosterone (CORT thereafter) in regulation of migratory departure, we analyzed the relationships between CORT levels and factors associated with departure probability in European robins (Erithacus rubecula) blood sampled at two nearby stopover sites during six autumn and six spring migration seasons. Contrary to predictions, in both migration seasons we observed higher CORT levels in lean birds, which are assumed to have low departure motivation. We found no indication that CORT concentrations increased in fat individuals captured around sunset, presumably shortly before departure. In parallel with departure likelihood, CORT levels increased towards the end of migration season in autumn, but there was no seasonal trend in spring, when motivation to continue migration is higher. Finally, CORT levels were positively related to tailwind component in autumn, whereas the opposite trend was observed in spring. In summary, our results provide mixed support for the hypothesis that CORT indicates departure readiness in songbirds. We propose that the observed relationships are more consistent with metabolic functions of CORT. Our study highlights the value of multiyear data and seasonal comparisons in studies of the endocrine regulation of such complex behaviors as departure decision.
在迁徙过程中，鸟类必须反复决定何时结束中途停歇并重新开始迁徙飞行。此类决定极大地影响它们整体的迁徙成功率，最终影响其适应性。随着能量储备水平提高、有正向风的支持以及迁徙季节的推进，出发概率会增加。然而，我们对这一过程背后的内分泌机制的了解仍不完整。为了评估基础皮质酮（以下简称CORT）在调节迁徙出发中的可能作用，我们分析了在六个秋季和六个春季迁徙季节，于两个相邻中途停歇地采集的欧洲知更鸟（欧亚鸲）血液中CORT水平与和出发概率相关的因素之间的关系。与预测相反，在两个迁徙季节中，我们都观察到瘦鸟的CORT水平较高，而瘦鸟被认为出发动机较低。我们没有发现迹象表明在日落前后捕获的、可能即将出发的肥鸟体内CORT浓度会升高。与出发可能性一致，秋季迁徙季节结束时CORT水平升高，但春季没有季节性趋势，而春季继续迁徙的动机更高。最后，秋季CORT水平与顺风分量呈正相关，而春季则观察到相反的趋势。总之，我们的结果对CORT表明鸣禽准备好出发这一假设提供了喜忧参半的支持。我们认为观察到的这些关系更符合CORT的代谢功能。我们的研究突出了多年数据和季节性比较在研究诸如出发决定等复杂行为的内分泌调节方面的价值。
