Billions of birds migrate north in the spring and south in the fall. The majority of them fly at night. But as they pass over large cities, the birds can become disoriented by bright artificial light – so-called light pollution, causing them to crash into buildings or windows.
Researchers estimate that 600 million birds die from building collisions in the United States every year. Now, a new paper from researchers at Cornell University reveals which metropolitan areas are most dangerous for birds and why.
The researchers ranked cities where, as a result of geography and exposure to light pollution, birds are at the greatest risk of becoming attracted to and disoriented by lights and crashing into buildings. They combined light pollution levels with bird density data in order to make their calculations. Their paper was recently published in the journal Frontiers in Ecology and the Environment.
Chicago, Houston, and Dallas finished as the three most dangerous cities for migrating birds. While migration routes vary depending on the season, these three cities still topped all others during both the spring and fall migrations due to their size and geographic positioning in the heart of North America’s most trafficked aerial corridors.
Audubon’s Lights Out program is one of several national efforts encouraging cities to reduce light pollution, particularly on heavy migration nights, in order to reduce bird mortality.
But homeowners need to do their part as well since an estimated quarter-million birds die from collisions with residential houses every year. The suggestion to cities and homeowners alike is the same: If you don’t need the lights, turn them off.
Photo, posted May 18, 2017, courtesy of Pedro Szekely via Flickr.