WASHINGTON -- Is the pursuit of fewer dropped calls leading to more dropping birds?
The lights atop communications towers that warn pilots to stay away can have a come-hither effect on birds -- killing millions of migrating warblers, thrushes and other species every year.
During bad weather, birds can mistake tower lights for the stars they use to navigate. They will circle a tower trancelike, often until they crash into the structure, its guy wires or other birds. Sometimes disoriented birds simply plummet to the ground from exhaustion.
The fatally hypnotic effect of warning beacons on birds is not a new phenomenon; early lighthouses attracted swarms of birds. But as towers proliferate to accommodate an ever-growing number of mobile phones and other devices, conservationists say bird deaths are climbing.
"We're talking about estimates of millions of birds dying because of these towers," said Paul Schmidt, assistant director for the migratory bird program at the U.S. Fish and Wildlife Service, which has pegged the annual deaths at 4 million to 50 million.
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Precise numbers are elusive, because many of the approximately 105,000 lighted communications towers nationwide are in isolated areas and scavengers waste little time feasting on the dead birds.
It's another example of the conflict between technology and nature -- a battle that has not gone well for migratory birds. Along with losing their habitats to development, their flyways are increasingly mined with deadly windmills, power lines and confusing reflective-glass skyscrapers.
Lacking definitive studies on birds and towers, the communications industry questions the wisdom of adding costly new regulations at a time when more towers are needed for expanding cellular phone service and high-definition TV and radio broadcasts.
"We don't want to be anti-conservation ... but you have to sort of balance that with this transition we're making to this next generation of technology," said Dennis Wharton, a spokesman for the National Association of Broadcasters. "So far, according to our engineers and scientists, it's still open to a lot of debate."
That debate has begun in Washington.
Spurred by environmental groups, the Federal Communications Commission announced this month that it was considering new tower regulations. The agency is asking for more data about the effect of a tower's height and the use of steadying guy wires. And the FCC is proposing that new and modified towers use more expensive white strobe lights instead of the steadily burning red ones now on most towers.
Researchers said red light waves may interfere with the magnetic compass of migratory birds, and some studies have indicated that blinking lights are less alluring.
"If you have a strobe light that even allows for a momentary period of darkness, it breaks that sort of spell and the birds are allowed to escape," said Darin Schroeder, deputy director of conservation advocacy at the American Bird Conservancy.
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Researchers first noticed birds' strange attraction to lights in the night sky more than 100 years ago when they flocked to the beacons of lighthouses. In the aftermath of explosions at off-shore oil platforms, flames have lured scores of birds to fiery deaths.
"We don't completely understand it," said Travis Longcore, science director of the Urban Wildlands Groups, a Los Angeles-based conservation organization. "They will not leave the zone of the light. They will be attracted to it and circle it."
