Each year, when migratory North American birds attempt their flight to Central and South America, more than seven million die in collisions with communications towers. Only house cats result in more human-induced bird deaths.
Many birds migrate at night. Bird mortality is greatest when communications towers are illuminated by floodlights. Lights protect structures from aircraft, but leave birds in a bewildered state of disorientation that often ends up in death.
Taller towers are deadlier than their shorter counterparts, with recent studies documenting that communications towers up to 1000 feet account for 70 times more bird deaths compared to towers only 300 feet tall.
Changes in lighting could help reduce bird collisions. Scott Loss is a professor at Oklahoma State University.
“For communication towers, a study that was conducted a couple years back assessing results of bird-collision mortality across a large number of study sites across the U.S., found that – in general – changing from a steady, burning light to a flashing light tended to reduce mortality rates of birds at communication towers. This is likely because, with the break in lighting, the birds are able to break their entrapment or trance with that light and continue flying on their migration. With buildings – skyscrapers specifically – it’s been illustrated, at least anecdotally, that turning off the lights of these buildings at nights can substantially reduce collision rates again.”
The Federal Aviation Administration and the Federal Communications Commission are responsible for developing the best regulations to keep tall towers from interfering with airplanes. Let’s hope that they will apply these recent scientific studies to help protect birds as well.
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Web Extra
Full interview with Scott Loss, a professor at Oklahoma State University
[audio:http://wamcradio.org/EarthWise/wp-content/uploads/2014/03/Loss_full_web.mp3|titles=Loss_full_web].
Web Links
Please see: Gehring, J., et al. (2009). Communication towers, lights, and birds: Successful methods of reducing the frequency of avian collisions. Ecological Applications 19: 505-514.
Longcore, T., et al. (2013). Avian mortality at communication towers in the United States and Canada: which species, how many, and where? Biological Conservation 158: 410-419.
Photo, taken October 3, 2012, courtesy of Andy Reago and Chrissy McClarren via Flickr.
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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.