Mitigating Bird Window Collisions
Up to one billion birds are estimated to collide with buildings, in cities and neighborhoods, in the US every year and even more throughout the world. These are occurring because of artificial light at night and/or glass reflections which can be confusing for them.
American Bird Conservancy: How to Keep Birds from Hitting Windows

Lights and Birds
Many bird species migrate at night using a variety of cues to navigate including the earth’s magnetic field and stars. This makes them especially sensitive to light and nighttime artificial lights can be disorienting for them. Window Lights can actually cause fatal window collisions for birds.
What you should know about Bird Migration and Light Pollution
Philadelphia has dimmed its skyline after a ‘mass collision’ killed thousands of migrating birds