Artificial night lighting is globally ubiquitous. Although recent work suggests this stressor can have a variety of consequences for wild animals, our understanding of species and context-specific variation in responses to this stimulus lags, as does our knowledge of whether effects of light exposure changes in the presence of other stressors. Here, I present results from two continental-scale studies that leveraged data from over 58,000 nest records and 3.5 million observations from citizen science efforts to understand the consequences of exposure to artificial night lighting while accounting for the influence of other aspects of human activity. Breeding birds exposed to light began nesting substantially earlier than those in dark regions and the effect was especially pronounced for open-habitat birds. Forest-habitat birds laid larger clutches with increases in light exposure. Species-specific variation in response to light was consistently explained by variation in eye geometries; birds with better low light vision advanced breeding most strongly with light exposure, but also benefit from light exposure in terms of overall nest success. In general, abundance of overwintering birds at feeders was not strongly influenced by light exposure, except the context of multiple stressors. Specifically, co-exposure to noise exacerbate negative responses to light and birds tended to increase in abundance with light exposure during longer winter nights. Although most species tended to increase in abundance with light exposure, the abundance of birds from forested habitats declined strongly with light exposure. Together, these results not only suggest that artificial light has widespread but heterogeneous effects on birds, but also provide important insights on the intrinsic and extrinsic factors responsible for variation in responses.