Sutro Tower in San Francisco, California. Photo: Marc Liyanage/Flickr CC (BY-SA 2.0)

Conservation

How Flashing Lights on Cell Towers Can Save Birds’ Lives

As many as 7 million birds in the U.S. die every year when they strike communication towers, but not for much longer.

Did you know that every time you turn on the radio or TV a bird dies?

Okay, that's not exactly true, but an estimated 7 million birds do die every year when they fly into the thick cables known as guy wires that hold up tall radio or TV communication towers. The birds, it turns out, are attracted by the same solid red lights that alert passing aircraft to the towers’ presence. The lights undoubtedly save human lives (preventing plane collisions), but for birds they can be deadly.

But a new solution might protect birds and people. This December, after several years of work by a broad range of conservationists, the Federal Aviation Administration finally announced new guidelines that will allow towers to turn off those solid red lights and replace them with flashing red lights which don’t attract birds the same way. Not only will this save tower operators electricity and money, it should reduce the number of bird fatalities around those towers by between 50 and 70 percent.

What birds will benefit?

The changes will be most significant for 13 species of conservation concern, including neo-tropical migratory birds such as Yellow Rails, Swainson’s Warblers, Pied-billed Grebes and Prairie Warblers. Research published in 2013 revealed that more than 2 percent of the total population for each of these species dies each year, thanks to collisions with communication tower wires.

“Birds are sort of captured by the spell of the lights,” explains University of Southern California assistant professor Travis Longcore, who led the research that first identified the scope of the collision problem.

It’s not entirely clear why flashing lights are better for birds—part of that mystery is why the steady lights attract birds in the first place. Many mortality events occur after storms push migrating birds to lower elevations, where they encounter the tallest communication towers (those from 900 to nearly 2,000 feet). One theory is that the solid red lights on these towers then interfere with a bird’s magnetic compass, leading them into the guy wires around them. Whatever happens, that effect, according to a study conducted on Michigan communication towers in 2005 under the leadership of principal investigator Joelle Gehring (now a biologist with the Federal Communications Commission), is mitigated when only flashing lights are present.

The FAA granted a special variance on tower lighting for that initial study research to be conducted, said Al Manville, now retired, who chaired a communication tower working group while with the U.S. Fish and Wildlife Service. That combined with the more recent research finally inspired the FAA to conduct its own study on flashing lights—they needed to make sure that pilots would still be able to see the towers without steady beams.

“Kudos to Joelle and clearly to the FAA,” says Manville. “Clearly with all of the other challenges that the agency faces, from drones to aircraft security, protecting birds is probably not high on their agency priority. To their credit they have stepped outside the box and made this happen. I think that’s a major step forward.”

How to replace thousands of bulbs

The lights won’t change all at once—the FAA’s new policies affect all new tower construction immediately. Existing towers will have until September 15, 2016 to switch over—and with many bulbs to change (most towers have five lights per level and as many as six or seven levels per tower), it may take a few months. Tower operators actually have a big incentive to switch out the lights even beyond saving birds. Steady-burning red lights require thousands of dollars a year in energy expenditures, plus hundreds of additional dollars in labor costs for tower-climbers to replace bulbs that burn out more frequently. Blinking LED lights not only save energy, they’ll also last much longer. Plus—blinking lights save birds as soon as they’re swapped in.

Manville said, “if we can reduce that collision number by at least 50 percent, that’s a major effort.”

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