Anthropogenic noise is increasing in intensity and scope, resulting in changes to acoustic landscapes and largely negative effects on a range of species. In birds, noise can mask acoustic signals used in a variety of communication systems, including parent-offspring communication. As a result, nestling birds raised in noise may have challenges soliciting food from parents and avoiding detection by predators. Given that passerine nestlings are confined to a nest and therefore cannot escape these challenges, noise may also act as a chronic stressor during their development. Here, we raised Tree Swallow (Tachycineta bicolor) nestlings with or without continuous, white noise to test whether noise exposure affected baseline and stress-induced plasma, integrated feather corticosterone levels, and immune function. Stress physiology and immune function may also vary with the competitive environment during development, so we also examined whether noise effects varied with brood size and nestling mass. We found that overall, exposure to noise did not alter nestling stress physiology or immune function. However, light nestlings raised in noise exhibited lower baseline plasma and integrated feather corticosterone than heavy nestlings, suggesting alternative physiological responses to anthropogenic stimuli. Furthermore, light nestlings in larger broods had reduced PHA-induced immune responses compared to heavy nestlings, and PHA-induced immune responses were associated with higher levels of baseline plasma and feather CORT. Overall, our findings suggest that noise can alter the stress physiology of developing birds; however, these effects may depend on developmental conditions and the presence of other environmental stressors, such as competition for resources. Our findings may help to explain why populations are not uniformly affected by noise.

人为噪声的强度和范围都在增加，导致声学景观发生变化，并对一系列物种产生很大的负面影响。在鸟类中，噪声可以掩盖各种通信系统中使用的声学信号，包括亲子通信。因此，在噪音中长大的雏鸟可能会面临向父母索取食物和避免被掠食者发现的挑战。鉴于雀形目雏鸟被限制在巢中，因此无法逃避这些挑战，噪音也可能成为它们发育过程中的慢性压力源。在这里，我们饲养了树燕（Tachycineta bicolor) 有或没有连续白噪声的雏鸟，以测试噪声暴露是否影响基线和压力诱导的血浆、综合羽毛皮质酮水平和免疫功能。应激生理和免疫功能也可能随着发育过程中的竞争环境而变化，因此我们还检查了噪音效应是否随育雏大小和雏鸟质量而变化。我们发现，总体而言，暴露于噪音并不会改变雏鸟的应激生理或免疫功能。然而，与重度雏鸟相比，在噪音中饲养的轻型雏鸟表现出较低的基线血浆和综合羽毛皮质酮，这表明对人为刺激的替代生理反应。此外，与重度雏鸟相比，较大雏鸟中的轻雏鸟减少了 PHA 诱导的免疫反应，和 PHA 诱导的免疫反应与较高水平的基线血浆和羽毛 CORT 相关。总的来说，我们的研究结果表明，噪音可以改变发育中鸟类的应激生理。然而，这些影响可能取决于发育条件和其他环境压力因素的存在，例如资源竞争。我们的发现可能有助于解释为什么人群不会受到噪音的一致影响。