Cornell Laboratory of Ornithology, Cornell University, Ithaca, NY, USA.
Department of Entomology and Wildlife Ecology, University of Delaware, Newark, DE, USA.
Glob Chang Biol. 2017 Nov;23(11):4609-4619. doi: 10.1111/gcb.13792. Epub 2017 Jul 11.
The spatial extent and intensity of artificial light at night (ALAN) has increased worldwide through the growth of urban environments. There is evidence that nocturnally migrating birds are attracted to ALAN, and there is evidence that nocturnally migrating bird populations are more likely to occur in urban areas during migration, especially in the autumn. Here, we test if urban sources of ALAN are responsible, at least in part, for these observed urban associations. We use weekly estimates of diurnal occurrence and relative abundance for 40 nocturnally migrating bird species that breed in forested environments in North America to assess how associations with distance to urban areas and ALAN are defined across the annual cycle. Migratory bird populations presented stronger than expected associations with shorter distances to urban areas during migration, and stronger than expected association with higher levels of ALAN outside and especially within urban areas during migration. These patterns were more pronounced during autumn migration, especially within urban areas. Outside of the two migration periods, migratory bird populations presented stronger than expected associations with longer distances to urban areas, especially during the nonbreeding season, and weaker than expected associations with the highest levels of ALAN outside and especially within urban areas. These findings suggest that ALAN is associated with higher levels of diurnal abundance along the boundaries and within the interior of urban areas during migration, especially in the autumn when juveniles are undertaking their first migration journey. These findings support the conclusion that urban sources of ALAN can broadly effect migratory behavior, emphasizing the need to better understand the implications of ALAN for migratory bird populations.
夜间人工光（ALAN）的空间范围和强度在全球范围内通过城市环境的发展而增加。有证据表明，夜间迁徙的鸟类会被 ALAN 吸引，并且有证据表明，在迁徙期间，夜间迁徙的鸟类种群更有可能在城市地区出现，尤其是在秋季。在这里，我们测试夜间人工光是否至少部分导致了这些观察到的城市关联。我们使用每周对 40 种在北美的森林环境中繁殖的夜间迁徙鸟类的日间出现和相对丰度的估计值，来评估它们与距离城市地区和 ALAN 的关系在整个年度周期内是如何定义的。在迁徙期间，候鸟种群与城市地区的距离较短，与城市地区内外的 ALAN 水平较高的关系比预期的更为紧密，而在秋季迁徙期间，这种关系更为明显，尤其是在城市地区内部。在两个迁徙期之外，候鸟种群与城市地区的距离较长的关系比预期的更为紧密，尤其是在非繁殖季节，而与城市地区内外的 ALAN 水平最高的关系比预期的更为薄弱。这些发现表明，在迁徙期间，尤其是在秋季，当幼鸟进行第一次迁徙之旅时，ALAN 与城市地区边界和内部的日间丰度水平较高有关。这些发现支持了夜间人工光可以广泛影响候鸟迁徙行为的结论，强调了需要更好地理解夜间人工光对候鸟种群的影响。
