Aispuro Armando Alberto, Maggini Ivan, Fusani Leonida, Canoine Virginie
Department of Interdisciplinary Life Sciences, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna, 1160, Vienna, Austria.
Coal Oil Point Reserve, University of California, Santa Barbara, CA, 93106, USA.
Sci Rep. 2025 Apr 6;15(1):11745. doi: 10.1038/s41598-025-95413-z.
Birds migrating in the spring must balance energy with hormonal preparations in anticipation of the forthcoming breeding season. We investigated the relationships between testosterone, body condition, sociality, territoriality and fueling rates in Western Subalpine Warbler (Curruca iberiae) males during a trans-Saharan stopover. Baseline testosterone was highly variable in correspondence with the transitional nature of spring stopover. Some individuals reached breeding testosterone levels while others had undetectable levels. Testosterone varied with body condition suggesting an endocrine-energy link during migration. Simulated territory intrusions induced an increase of testosterone up to physiological maxima- a similar pattern to breeding contexts. Testosterone was negatively associated with territorial male density, suggesting a 'dear enemy' effect related to the daily variation in social stability. In repeatedly-sampled individuals, stopover duration and fueling rate were not correlated with baseline testosterone. However, as testosterone decreased, body condition increased. This suggests that stopover territoriality may reduce the reported negative effects of chronically high testosterone. Our data supports the hypothesis that hormonal preparation for breeding may already occur during stopover, and that this is largely linked to body condition. In this system, the endocrine-energy relationship is likely maintained by stopover territoriality. We conclude that male-male social contexts are modulated in similar ways during spring migration as during the breeding life history stage.
春季迁徙的鸟类必须在为即将到来的繁殖季节做准备时，在能量与激素调节之间取得平衡。我们研究了雄性西部亚高山柳莺（Curruca iberiae）在跨撒哈拉中途停留期间，睾酮、身体状况、社会性、领地行为和取食率之间的关系。基线睾酮水平高度可变，这与春季中途停留的过渡性质相对应。一些个体达到了繁殖期的睾酮水平，而另一些个体的睾酮水平则检测不到。睾酮水平随身体状况而变化，这表明在迁徙过程中存在内分泌与能量的联系。模拟领地入侵会导致睾酮水平升高至生理最大值，这与繁殖环境中的模式相似。睾酮与领地雄性密度呈负相关，这表明存在与社会稳定性每日变化相关的“亲爱的敌人”效应。在重复采样的个体中，中途停留时间和取食率与基线睾酮水平无关。然而，随着睾酮水平下降，身体状况有所改善。这表明中途停留期间的领地行为可能会减轻长期高睾酮水平所带来的负面影响。我们的数据支持这样一种假设，即繁殖的激素准备可能在中途停留期间就已经发生，而且这在很大程度上与身体状况有关。在这个系统中，内分泌与能量的关系可能是由中途停留期间的领地行为维持的。我们得出结论，雄性之间的社会环境在春季迁徙期间的调节方式与繁殖生活史阶段相似。
