Flashing lights work better than steady ones to keep birds from hitting towers

Research from the Michigan field office of a federal agency is helping save the lives of songbirds — and also could save money for communications tower operators.

An estimated 7 million birds are killed annually in tower collisions across the USA, and most are songbirds that migrate at night. More than a decade ago staff at the East Lansing field office of the U.S. Fish and Wildlife Service coordinated hundreds of researchers across the state to count the number of injured and dead songbirds at the base of 24 communications towers during the peak of the birds' spring and fall migrations.

They concluded that towers with steadily burning lights were more deadly to the birds than towers with flashing lights, and that by simply turning off the steady lights they could reduce deadly bird-tower collisions by 70%.

The Federal Aviation Administration changed its lighting standards for new communication towers in December 2015 while the Fish and Wildlife Service recently began working to persuade owners and operators of existing towers across Michigan to turn off the burning lights or switch to flashing lights.

The lights are meant to protect aircraft from striking these towers.

The country has thousands of these towers that broadcasters, communications and telecommunications providers use. Only newly built towers are affected, and replacing or turning off the burning lights is voluntary for existing tower owners.

Owners of towers that have both steady and sufficient flashing lights simply can extinguish the steady lights. Experts say that could save owners money on maintenance and power costs.

Audubon Great Lakes, the Chicago-based office of the National Audubon Society, said it's willing to use its chapter network across the Great Lakes to reach out to tower owners and operators about switching or turning off lights. Work could begin this year.

"We're really pleased we had an opportunity to do something that has nationwide implications for migratory birds," said Jack Dingledine, deputy field supervisor at the wildlife service's East Lansing field office.

It all started in 1998 when the Fish and Wildlife Service learned Michigan had plans to build a telecommunications network of 179 towers.

"We had some concerns about the potential impact of those towers on migratory birds, including the endangered Kirtland's warbler," which nests almost exclusively in northern Michigan, Dingledine said.

The agency approached the state, asking for access to the base of the towers so researchers could measure the number of dead birds as they migrated between Michigan and the southern U.S., Central America and South America. The state also provided more than $100,000 for the research.

Led by Joelle Gehring, who was working on a post-doctorate at Central Michigan University at the time, researchers did pilot work at six towers in fall 2003. In the fall and spring of 2004 and 2005, for three weeks at a time, they counted dead birds at 24 towers from southwest Michigan to the Upper Peninsula.

Gehring and two colleagues published their study in a scientific journal in 2009, and the Federal Aviation Administration, which regulates tower lighting, did its own research to ensure aircraft would still be safe if the steady lights were turned off or replaced.

While the Federal Communications Commission licenses communications towers, it requires owners and operators to comply with standards set by the FAA.

Dingledine said researchers have discovered some evidence that the birds may be attracted to lights on the tower, especially in foggy weather, and then they collide with the tower or the wires that support the structure.

"The light can confuse them when they migrate," he said.

But scientists aren't exactly sure why the steady lights are more dangerous than blinking lights.

"Birds are a harbinger of the health of your ecosystem" so protecting these migrating songbirds is important, Dingledine said. "They are some of the most diverse species on earth, occur in every region of the planet and a good, healthy bird population means you have a good, healthy natural environment."

Caleb Putnam, Michigan bird conservation coordinator for Audubon Great Lakes and the Michigan Department of Natural Resources, called the Michigan research "one of the most important bird-mortality-reducing research done in recent memory."

Bird experts have tried for years to address the issue, and Gehring was able to "make a difference over thousands of towers," he said. "It's such a common-sense solution to a huge problem."

Putnam was one of the technicians who got up at dawn for three weeks straight to count dead birds at the base of a 1,100-foot-tall communications tower in southwest Michigan. The workers had to get to the site before daybreak, so they could find the birds before raccoons and other scavengers got them.

"We found birds alive, with their beaks broken off," Putnam said. On some days, he'd find 10 to 20 dead or injured warblers. But if the birds hadn't migrated the night before, he wouldn't find any.  And it wasn't easy spotting them in the tall grass that surrounded much of the tower.

Saving those birds from tower collisions is part of the effort to "prevent future extinctions," Putnam said.

"The challenge is that most of our songbird populations are in decline," he said. "Many of these species are lacking habitat in breeding areas, and as they get into the tropics, there is deforestation, coffee plantations, climate issues, all these other pressures on them.

"To not allow these species to migrate successfully twice a year, especially with this level of mortality, it starts to become a population-changing pressure," Putnam said.

Follow Jennifer Dixon on Twitter: @jennbdixon