Light pollution caused by human development is something to which animals have had to adapt. Unfortunately, it can have negative impacts, including to the success of turtle nests and to the safety of migrating birds. New research shows it may also be messing with birds’ sleep-wake cycles.

A pair of researchers from Southern Illinois University Carbondale and Oklahoma State University recently analyzed more than 180 million bird vocalizations from 583 species across the globe to understand how they’re responding to light pollution.

Using global satellite imagery and machine learning to convert vocalizations to visualizations, the team found that, on average, birds were vocal for 50 more minutes each day in areas with more light pollution. That was just an average, too, with variations between species. The species most impacted were those with big eyes and open nests and those that migrate and have large ranges. It was especially common during breeding season, as well.

What’s behind this behavior?

Brent Pease, study co-author and assistant professor in SIU’s School of Forestry and Horticulture, says, “The next question was: why? What is driving this response by birds? We had the idea that maybe it was a species’ photoreceptor sensitivity – their eyesight. And this turned out to be a key factor. Species with large eyes relative to their body size had a disproportionately stronger response to artificial light at night. They were more sensitive to light at night than species with small eyes.”

Going forward, the researchers say it will also be important to learn how the increased wakefulness impacts bird health.

If you’d like to help minimize the light pollution you contribute, the U.S. Fish and Wildlife Service says you can turn off any unnecessary outdoor lighting, keep outdoor lighting low to the ground and avoid pointing it upward or toward the landscape, close your blinds and curtains at night, and use warmer-colored light bulbs less apt to cause problems for birds. This is especially important during spring and fall migration season, when light pollution can disrupt the flight paths of migrating birds, causing them to deplete their energy stores, be more apt to collide with a building, and be at higher risk of predators. You can read more tips here!