The average bird can cruise between three-inch openings in dense woodlands at upwards of 20-30 mph—so it may seem safe to assume they can easily maneuver around giant city buildings. Unfortunately for our feathered friends, that’s just not the case.
Experts say that up to 1 billion birds die in North America each year due to building collisions. If it’s lit up at night, the average big building kills about 1,000 birds a year.
Why is navigating around city buildings so tough for migrating birds? A deadly combination of glass, light, and disorientation means that birds are actually drawn to the structures.
Birds don’t visually register glass. Instead, they see it as an opening or a reflection—possibly an inviting one. When lit up, a landscaped lobby—or even a desktop plant—can attract birds looking to roost in the early morning hours…exactly when flight-weary birds are most disoriented.
Reflections pose a similar problem: When glass reflects leafy trees outside, birds can’t differentiate and often hurl themselves into the reflected mirage.
Lights also perplex night-time migrants, because birds use the stars and moon to orient themselves. To a tired bird, urban building lights look a lot like celestial ones. Some experts think that’s why birds sometimes circle the top of a lit building for hours, only to drop out of the sky in fatigue.
The good news is, you can help with one simple change— turn off the lights in your home and office at night, especially during spring and fall migration seasons.
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This segment was contributed by our friends at EcoMyths.
To learn more about birds and buildings, visit: http://ecomythsalliance.org/2012/05/flight-club-birds-vs-buildings/
Photo, taken on August 1, 2012, courtesy of Kristina Hoeppner via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY, with partial support from the Field Day Foundation.