Lights Out

Every year, billions of birds migrate north in the spring and south in the fall, the majority of them flying at night, navigating with the night sky. However, as they pass over big cities on their way, they can become disoriented by bright artificial lights and skyglow, often causing them to collide with buildings or windows. While lights can throw birds off their migration paths, bird fatalities are more directly caused by the amount of energy the birds waste flying around and calling out in confusion. The exhaustion can then leave them vulnerable to other urban threats.

https://www.audubon.org/conservation/project/lights-out