Data from: Stressful city sounds: glucocorticoid responses to experimental traffic noise are environmentally dependent

A major challenge in urban ecology is to identify the environmental factors responsible for phenotypic differences between urban and rural individuals. However, the intercorrelation between the factors that characterise urban environments, combined with a lack of experimental manipulations of these factors in both urban and rural areas, hinder efforts to identify which aspects of urban environments are responsible for phenotypic differences. Among the factors modified by urbanisation, anthropogenic sound, particularly traffic noise, is especially detrimental to animals. The mechanisms by which anthropogenic sound affects animals are unclear, but one potential mechanism is through changes in glucocorticoid hormone levels. We exposed adult house wrens, Troglodytes aedon, to either traffic noise or pink noise. We found that urban wrens had higher initial (pre-restraint) corticosterone than rural wrens before treatment, and that traffic noise elevated initial corticosterone of rural, but not urban, wrens. By contrast, restraint stress-induced corticosterone was not affected by noise treatment. Our results indicate that traffic noise specifically contributes to determining the glucocorticoid phenotype, and suggest that glucocorticoids are a mechanism by which anthropogenic sound causes phenotypic differences between urban and rural animals.

城市生态学的一项核心挑战，在于识别导致城乡个体间表型差异的环境因子。然而，表征城市环境的各类因子之间存在相互关联，加之在城市和农村地区均缺乏对这些因子的实验操控手段，阻碍了学界甄别城市环境中哪些要素引发表型差异的研究进程。在城市化所改变的诸多环境因子中，人为噪声（anthropogenic sound），尤其是交通噪声（traffic noise），对动物的危害尤为显著。目前人为噪声影响动物的具体机制尚不明确，但其中一种潜在路径是通过改变糖皮质激素（glucocorticoid hormone）水平实现的。本研究将成年家鹪鹩（Troglodytes aedon）分别暴露于交通噪声与粉红噪声（pink noise）环境中。研究发现，实验处理前，城市家鹪鹩的初始（束缚前）皮质酮（corticosterone）水平高于农村家鹪鹩；且交通噪声仅会升高农村家鹪鹩的初始皮质酮水平，对城市家鹪鹩无此效果。与之相反，束缚应激（restraint stress）诱导产生的皮质酮水平并未受到噪声处理的影响。本研究结果表明，交通噪声可特异性地决定动物的糖皮质激素表型（glucocorticoid phenotype），同时提示糖皮质激素是人为噪声引发城乡动物表型差异的潜在机制。