The risk of predation directly affects the physiology, behavior, and fitness of wild birds. Strong social connections with conspecifics could help individuals recover from a stressful experience such as a predation event; however, competitive interactions also have the potential to exacerbate stress. Few studies have investigated the interaction between environmental stressors and the social landscape in wild bird populations. In 2 years of field studies, we experimentally simulated predation attempts on breeding female tree swallows (Tachicyneta bicolor). At the same time, we manipulated female breast plumage color, a key social signal. Simulated predation events on tree swallows early in the nestling period reduced young nestlings' mass by approximately 20% and shortened telomere lengths. Ultimately, only 31% of nestlings in the predation group fledged compared with 70% of control nestlings. However, the effects of experimental manipulations were timing dependent: the following year when we swapped the order of the experimental manipulations and simulated predation during incubation, there were no significant effects of predation on nestling condition or fledging success. Contrary to our expectations, manipulation of the social environment did not affect the response of tree swallows to simulated predation. However, manipulating female plumage during the nestling period did reduce nestling skeletal size and mass, although the effects depended on original plumage brightness. Our data demonstrate that transient stressors on female birds can have carry‐over effects on their nestlings if they occur during critical periods in the breeding season.

中文翻译：

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感知捕食风险对雏鸟树燕（Tachycineta bicolor）的发育阶段依赖性影响

被捕食的风险直接影响野生鸟类的生理、行为和健康。与同种人之间牢固的社会联系可以帮助个体从捕食事件等压力经历中恢复过来；然而，竞争性互动也有可能加剧压力。很少有研究调查环境压力源与野生鸟类种群社会景观之间的相互作用。在两年的实地研究中，我们通过实验模拟了繁殖雌性树燕的捕食行为（双色鞑靼）。与此同时，我们操纵了雌性乳房羽毛的颜色，这是一个关键的社会信号。雏鸟早期对树燕的模拟捕食事件使雏鸟的体重减少了约 20%，端粒长度也缩短了。最终，捕食组中只有 31% 的雏鸟长出了羽毛，而对照组雏鸟的这一比例为 70%。然而，实验操作的效果是时间依赖性的：第二年，当我们在孵化期间交换实验操作和模拟捕食的顺序时，捕食对雏鸟状况或羽翼未丰的成功没有显着影响。与我们的预期相反，社会环境的操纵并没有影响树燕对模拟捕食的反应。然而，在雏鸟期间操纵雌性羽毛确实减少了雏鸟的骨骼尺寸和质量，尽管效果取决于原始羽毛的亮度。我们的数据表明，如果母鸟的短暂压力发生在繁殖季节的关键时期，可能会对雏鸟产生持续影响。