Light and reflective glass act as invisible killers for migratory birds. Collisions with buildings, and particularly windows, are a major anthropogenic threat to birds, with rough estimates of one billion birds killed annually in the United States.

For one, nocturnal migratory birds are attracted to lights on structures such as communication towers and tall buildings, especially on nights with fog or low clouds. Due to the attraction of light, birds can become disoriented and trapped, many of them colliding fatally or becoming exhausted, making them more vulnerable to predation.

On the other hand, glass can act as a mirror for diurnal migratory birds that try to reach the images reflected in the glass, hitting it and causing injuries that in many cases result in death. In North America, most victims of window collisions are migratory birds that move north in spring to breed in the Arctic tundra, or south in autumn to spend the winter in warmer areas near the tropics or even in South America.

In this sense, New York City is a key stop for migratory birds following the Atlantic route. The highest number of bird collisions in the city occur in both spring and fall, with significantly more fatalities in fall than spring. In collaboration with NYC Audubon, I’ve been reporting on bird collisions at different hotspots in downtown Manhattan, as well as documenting the work at the Wild Bird Fund, the wildlife rehabilitation center that cares for injured birds. Bird collisions are a large-scale conservation issue and the second leading cause of avian mortality. But the good news is that this problem is preventable, and we can all help by using bird-friendly solutions on our windowsills. Furthermore, it is important to raise awareness and reach out to both local and state governments to achieve a change in legislation that allows the implementation of bird-friendly glass in cities, especially at critical collision points, as well as supporting developers and builders in the implementation of such infrastructures.