Common Yellowthroat, © Michael R. Duncan

Blinded by the Light

Migrating birds fly high, fast and far from the United States and Canada to Central and South America. But on a cloudy night, the sight of a red light on a communication tower can draw them in and hold them spellbound.

Nearly 7 million migrating birds die a year, victims of the 84,000 towers that dot the North American skyline, according to a University of Southern California study, funded in part by Defenders of Wildlife.

During stormy weather, clouds obscure the stars and force birds to fly at lower levels without their navigational tools. Blinking tower lights don’t confuse them. It’s the steady-burning red ones. The birds end up circling the tower and run into the dozens of cables, known as guy wires, that prop up a tower.

Researchers found the taller the tower, the greater the threat. Of the 84,000 communication towers in North America, only 1,000 or so rise above 900 feet, but they account for 70 percent of the tower-related bird deaths. “That amounts to a staggering 4.5 million birds each year,” says Chris Haney, Defenders’ chief scientist.

The study does offer some solutions: Change the steady-burning lights on tall towers, share towers and build freestanding towers to reduce the need for guy wires. “Methods to reduce this lethal mortality are the best long-term solution,” adds Haney.

Read more stories from the summer issue of Defenders.