Data from: Artificial light at night advances avian reproductive physiology

Artificial light at night is a rapidly increasing phenomenon and it is presumed to have global implications. Light at night has been associated with health problems in humans as a consequence of altered biological rhythms. Effects on wild animals have been less investigated, but light at night has often been assumed to affect seasonal cycles of urban dwellers. Using light loggers attached to free-living European blackbirds (Turdus merula), we first measured light intensity at night which forest and city birds are subjected to in the wild. Then we used these measurements to test for the effect of light at night on timing of reproductive physiology. Captive city and forest blackbirds were exposed to either dark nights or very low light intensities at night (0.3 lux). Birds exposed to light at night developed their reproductive system up to one month earlier, and also moulted earlier, than birds kept under dark nights. Furthermore, city birds responded differently than forest individuals to the light at night treatment, suggesting that urbanization can alter the physiological phenotype of songbirds. Our results emphasize the impact of human-induced lighting on the ecology of millions of animals living in cities and call for an understanding of the fitness consequences of light pollution.

夜间人工光照是一种快速增长的全球性现象，其潜在影响备受关注。现有研究表明，夜间光照会通过扰乱人体生物节律，引发各类健康问题。但目前针对野生动物的相关研究仍较为匮乏，学界普遍推测夜间光照会干扰城市栖息野生动物的季节性生理周期。本研究通过为野生欧亚乌鸫（Turdus merula）佩戴光照记录仪（light loggers），首次实测了森林与城市生境中野生鸟类夜间所承受的光照强度；随后基于该实测数据，探究夜间光照对鸟类繁殖生理节律时序的调控效应。实验中将圈养的城市与森林来源乌鸫分为两组，分别置于全黑夜间环境与0.3勒克斯（lux）的极低夜间光照环境中。相较于全黑夜间环境下的个体，暴露于夜间光照的乌鸫其生殖系统发育提前可达一个月，换羽周期也同步提前。此外，城市来源与森林来源的乌鸫对夜间光照处理的响应存在显著差异，这表明城市化进程可改变鸣禽的生理表型。本研究结果凸显了人为光照对全球城市栖息数百万野生动物生态学特征的影响，并呼吁学界进一步探究光污染对动物适合度的潜在后果。