The ecological impact of artificial light at night (ALAN) on phenological events such as reproductive timing is increasingly recognized. In birds, previous experiments under controlled conditions showed that ALAN strongly advances gonadal growth, but effects on egg-laying date are less clear. In particular, effects of ALAN on timing of egg laying are found to be year-dependent, suggesting an interaction with climatic conditions such as spring temperature, which is known have strong effects on the phenology of avian breeding. Thus, we hypothesized that ALAN and temperature interact to regulate timing of reproduction in wild birds. Field studies have suggested that sources of ALAN rich in short wavelengths can lead to stronger advances in egg-laying date. We therefore tested this hypothesis in the Great Tit (Parus major), using a replicated experimental set-up where eight previously unlit forest transects were illuminated with either white, green, or red LED light, or left dark as controls. We measured timing of egg laying for 619 breeding events spread over six consecutive years and obtained temperature data for all sites and years. We detected overall significantly earlier egg-laying dates in the white and green light vs. the dark treatment, and similar trends for red light. However, there was a strong interannual variability in mean egg-laying dates in all treatments, which was explained by spring temperature. We did not detect any fitness consequence of the changed timing of egg laying due to ALAN, which suggests that advancing reproduction in response to ALAN might be adaptive.

中文翻译：

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夜晚的人造光与春天的温度相互作用，调节了雀形目鸟的繁殖时间。

人们越来越认识到夜间人造光（ALAN）对诸如繁殖时间等物候事件的生态影响。在禽类中，先前在受控条件下进行的实验表明，ALAN可以强烈促进性腺的生长，但是对产卵日期的影响尚不清楚。尤其是，发现ALAN对产卵时间的影响与年份有关，这表明它与气候条件（如春季温度）的相互作用是众所周知的，这种相互作用对禽类的繁殖物候具有很强的影响。因此，我们假设ALAN和温度相互作用以调节野生鸟类的繁殖时机。现场研究表明，富含短波长的ALAN的来源可导致产卵期更强劲的发展。因此，我们在大山雀（Parus major）中验证了这一假设，使用复制的实验设置，其中八个，以前未照明的森林样条都用白色，绿色或红色LED灯照明，或保持黑暗作为对照。我们测量了连续六年中发生的619个繁殖事件的产卵时间，并获得了所有地点和年份的温度数据。我们发现白光和绿光与暗光处理相比，整体上明显早于产卵日期，而红光的趋势也相似。但是，在所有处理中，平均产卵日期的年际变化都很大，这可以通过春季温度来解释。我们没有发现由于ALAN引起的产卵时间变化的适应性结果，这表明响应ALAN促进繁殖可能是适应性的。