Department of Evolutionary Biology Leo Pardi, University of Florence, Via Romana 17, 50125 Florence, Italy.
Horm Behav. 2011 Sep;60(4):414-9. doi: 10.1016/j.yhbeh.2011.07.010. Epub 2011 Jul 22.
In many birds and mammals, male territorial aggression is modulated by elevated circulating concentrations of the steroid hormone testosterone (T) during the breeding season. However, many species are territorial also during the non-breeding season, when plasma T levels are basal. The endocrine control of non-breeding territorial aggression differs considerably between species, and previous studies on wintering birds suggest differences between migratory and resident species. We investigated the endocrine modulation of territorial aggression during the breeding and non-breeding season in a resident population of European stonechats (Saxicola torquata rubicola). We recorded the aggressive response to a simulated territorial intrusion in spring and winter. Then, we compared the territorial aggression between seasons and in an experiment in which we blocked the androgenic and estrogenic action of T. We found no difference in the aggressive response between the breeding and the non-breeding season. However, similarly to what is found in migratory stonechats, the hormonal treatment decreased aggressive behaviors in resident males in the breeding season, whereas no effects were recorded in the non-breeding season. When we compared the aggressive responses of untreated birds with those obtained from migratory populations in a previous study, we found that territorial aggression of resident males was lower than that of migratory males during the breeding season. Our results show that in a resident population of stonechats T and/or its metabolites control territorial aggression in the breeding but not in the non-breeding season. In addition, our study supports the hypothesis that migratory status does modulate the intensity of aggressive behavior.
在许多鸟类和哺乳动物中，雄性的领地侵略行为在繁殖季节会受到循环中类固醇激素睾酮（T）浓度升高的调节。然而，许多物种在非繁殖季节也具有领地性，此时血浆 T 水平处于基础状态。非繁殖季节领地侵略的内分泌控制在物种之间有很大的差异，并且对越冬鸟类的先前研究表明迁徙和留鸟物种之间存在差异。我们研究了繁殖和非繁殖季节中留鸟欧洲石鸻（Saxicola torquata rubicola）的领地侵略的内分泌调节。我们记录了在春季和冬季模拟领地入侵时的侵略反应。然后，我们比较了季节之间和实验中雄性激素阻断雄激素和雌激素作用的情况下的领地侵略行为。我们发现繁殖季节和非繁殖季节之间的侵略反应没有差异。然而，与迁徙石鸻中的情况类似，激素处理降低了繁殖季节中留鸟雄性的侵略行为，但在非繁殖季节中没有记录到这种影响。当我们将未经处理的鸟类的侵略反应与之前的一项研究中迁徙种群的结果进行比较时，我们发现繁殖季节中留鸟雄性的领地侵略性低于迁徙雄性。我们的研究结果表明，在石鸻的留鸟种群中，T 和/或其代谢物在繁殖季节控制领地侵略，但在非繁殖季节不控制。此外，我们的研究支持了迁徙状态会调节侵略行为强度的假说。
