Data from: Experimental illumination of a forest: no effects of lights of different colours on the onset of the dawn chorus in songbirds

Light pollution is increasing exponentially, but its impact on animal behaviour is still poorly understood. For songbirds, the most repeatable finding is that artificial night lighting leads to an earlier daily onset of dawn singing. Most of these studies are, however, correlational and cannot entirely dissociate effects of light pollution from other effects of urbanization. In addition, there are no studies in which the effects of different light colours on singing have been tested. Here, we investigated whether the timing of dawn singing in wild songbirds is influenced by artificial light using an experimental set-up with conventional street lights. We illuminated eight previously dark forest edges with white, green, red or no light, and recorded daily onset of dawn singing during the breeding season. Based on earlier work, we predicted that onset of singing would be earlier in the lighted treatments, with the strongest effects in the early-singing species. However, we found no significant effect of the experimental night lighting (of any colour) in the 14 species for which we obtained sufficient data. Confounding effects of urbanization in previous studies may explain these results, but we also suggest that the experimental night lighting may not have been strong enough to have an effect on singing.光污染正以指数级速度加剧，但其对动物行为的影响迄今仍未得到充分阐释。对于鸣禽而言，现有研究中最具一致性的重复性结论为：夜间人工照明会导致其每日黎明鸣唱的启动时间提前。然而，此类研究大多属于相关性研究，无法完全区分光污染与城市化其他因素各自产生的效应。此外，目前尚无研究检验不同光色对鸣禽鸣唱行为的影响。本研究依托常规路灯搭建的实验平台，探究野生鸣禽的黎明鸣唱启动时间是否会受人工照明的影响。我们对8处此前无人工照明的林缘生境分别施加白光、绿光、红光照明，以及无照明的对照处理，并在繁殖季逐日记录其黎明鸣唱的启动时间。基于前期相关研究，我们曾预设：接受照明处理的区域内，鸣禽的鸣唱启动时间会更早，且该效应在早鸣物种中最为显著。然而，在我们获取了足够有效数据的14个物种中，并未发现任何光色的实验性夜间照明对鸣唱启动时间存在显著影响。既往研究中城市化带来的混杂效应或许可以解释本次研究结果，但我们也提出，本次实验所采用的夜间照明强度可能不足以对鸣唱行为产生影响。