4-year study examines cell phone towers’ toll on birds
Posted on Monday, October 1, 2007
CONWAY — Leo Koch wades among tall grass, thorny cacti and shrubs, not to mention chiggers, ticks and fire ants. He climbs along a rugged hill and takes care not to step on any snakes.
It’s barely sunrise, and Koch’s eyes focus on the ground. His job is to scour the rugged field surrounding a cell-phone tower just northeast of Conway for bird carcasses, all in the name of science.
The tower is one of 15 in Arkansas where searchers are hunting for the carcasses of Neotropical migratory songbirds such as warblers and sparrows. It seems millions of these birds, which migrate at night, are crashing into some of the nation’s more than 85, 000 communications towers, at least 2, 000 of which are in Arkansas. Neotropical migratory birds breed in North America and spend their winters in warmer climates such as Mexico, Central and South America and the Caribbean.
The American Bird Conservancy noted last year that the U. S. Fish and Wildlife Service has estimated 5 million to 50 million birds are killed in tower collisions in this country each year. Most are songbirds whose navigation systems seem to be confused by tower lights, especially in bad weather, the Virginia-based conservancy said.
On a recent cool morning after more than two hours in the wet field, Koch had found just three feathers but not a single bird killed the night before.
“It looks like we’ve had some lucky birds,” he said, smiling.
Koch, 25, of Conway is participating in the third year of a four-year study aimed at assessing the extent of the problem in Arkansas and determining what types of towers — tall ones, short ones; towers with red lights, towers with white ones; towers with guy wires, towers without them — are more likely to have bird strikes.
The state and federally funded study is the subject of a doctoral dissertation planned by Erin Macchia, an environmental sciences student at Arkansas State University in Jonesboro.
Macchia, 31, hopes the project will “identify a tower structure or structures that will minimize the impact of communication towers on migrating birds.”
She noted the birds don’t have the sun as a guide when migrating. Further, when cloud cover gets lower during a storm front, they tend to fly lower, increasing the likelihood of striking a tower or other structure.
Participants began checking the sites Sept. 10 and will continue five days per week through Friday.
Six towers are being checked in the Jonesboro area, three in the Fayetteville area, and others in or near Conway, Stuttgart, Pine Bluff, Hot Springs Village, Benton and Russellville.
As of Sept. 20, Koch had found at least 10 feather piles, but no carcasses. But five of eight brown-headed cowbird carcasses he placed at the site at the start of the project quickly vanished — an experiment intended to find out how many dead birds are being devoured by night predators.
Macchia hasn’t tallied the carcasses yet, but she heard from a few searchers early on. She said one found three carcasses in three days. She checks the three Fayetteville sites where as of Sept. 20 she had found two carcasses of red-eyed vireos and eight feather piles — at least two of which belonged to yellow-billed cuckoos. Five or more feathers together count as a bird.
Searchers bag the carcasses and freeze them until Macchia collects them and takes them to an ASU laboratory for identification.
“The most birds we’ve ever recovered in one day of searching [at one site ] was six, Macchia said.
She tries to remind searchers that “ when they don’t find birds, it means they’ve migrated successfully.”
Last spring, searchers recovered seven indigo buntings, more than any other species that season.
The species recovered most often in the Arkansas study in fall 2006 was the yellow-billed cuckoo, a long-tailed bird about the size of a blue jay.
“Because it’s a such large bird, it’s pretty easy to recover the carcasses,” Macchia said, noting seven were found that season. “But it’s also popular for scavengers. It makes a pretty big meal,” so searchers often find only feathers.
Two other species that show up regularly are red-eyed vireos and ovenbirds, a type of warbler.
Migrating songbirds start their flight at dusk and fly until they “settle down in the hours before dawn,” Macchia explained. “That’s when they’re affected, when they’re flying at night often in areas they’re not familiar with.”
The U. S. Fish and Wildlife Service offers recommendations to minimize tower danger. Suggestions include building towers less than 200 feet tall so they won’t have to be lighted under Federal Aviation Administration regulations.
If a tower must be lighted, the service recommends white strobe lights rather than red incandescent ones which are thought more likely to disorient birds. The service also suggests self-supporting structures rather than guy wires.
“We have to recognize that towers are absolutely necessary for our communication needs,” said Jim Bednarz, an ASU professor of wildlife ecology who has worked with Macchia. “What [Macchia ] intends to do is to provide suggestions to the communications industry that will enable [it ] to construct towers in the future that will have less impact on birds.”
Catherine Rideout, ornithologist with the Arkansas Game and Fish Commission, said she thought the agency’s funding this year was about $ 50, 000. The study has obtained a $ 28, 000 matching grant from the federal government for next year, Macchia said.
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