Lights and Nighttime Collisions
The growth of brightly-lit urban areas along bird migration routes has increased exponentially since lighted structures appeared on the landscape. These areas pose a significant, often fatal threat to migrating birds, both during the day and throughout the night. This page focuses on the nighttime issue of city lights and bird-building collisions.
Many species of birds, especially the small insect-eaters, migrate at night. Night-migrating birds use the age-old and constant patterns of light from the moon, the stars, and from the setting sun as navigational tools to follow their migration routes.
Artificial, city lights interfere with this instinctive behavior and draw night-migrating birds toward brightly-lit buildings in urban areas. Researchers have used radar imagery to determine how birds respond to lit environments. The observations found that once they fly through a lit environment they’ll return to that lit source and then hesitate to leave it.
As humans, we can relate to this by recalling trips away from the city. Have you ever gone camping, or visited a cottage, and observed the splendor of countless bright stars in a black sky? We cannot see all of these stars at home because of the city lights.
The danger of artificial light to migrating birds is intensified on foggy or rainy nights, when the weather further obscures the night sky, or when cloud cover is low and the birds naturally migrate at lower altitudes. Disoriented, the birds are pulled off course and into an unfamiliar maze of lighted buildings. In trying to follow their instincts, they often collide with the windows or walls of the buildings, or even with other disoriented birds.
Floodlights, lighthouses, festival lighting and airport ceilometers (light beams used to determine the altitude of clouds) are also dangerous to migrating birds. The birds get trapped inside the beams of light and are reluctant to fly back out into the dark. They continue to circle inside the beams until they drop to the ground from exhaustion. Once on the ground, the stunned or injured birds become vulnerable to predation.
FLAP and the City of Toronto have collaborated on several innovative programs and policies aimed at getting the lights turned out at night in Toronto, and especially during migration seasons. Click here to learn more about Lights Out Toronto! (LOT!).
Outside of Toronto, cities across North America are coming together in an international, collaborative effort to save migrating birds by initiating similar Lights Out programs in their areas. Click here to learn more about the Great Lakes Lights Out Initiative.
Click here to learn what you can do to help make your home or workplace safe for birds.
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