Bird study comes up

BISMARCK — Despite spending $1 million, scientists haven’t been able to determine whether gadgets that flash, flap and have spirals are effective in keeping birds away from North Dakota power lines.

The study looked at so-called bird diverters on a causeway that separates Lake Audubon from Lake Sakakawea along the Missouri River. Biologists have called the 2-mile stretch along U.S. Highway 83 through the Audubon National Wildlife Refuge one of the world’s deadliest places for birds, which are killed in crashes with power lines and vehicles.

Results of the five-year study paid for by the federal government and utilities were released Thursday to The Associated Press.

“The study was inconclusive — unfortunately that’s the way science works sometimes,” said Randy Wilkerson, a Lakewood, Colo.-based spokesman with Western Area Power Administration, which owns the power lines.

One of the devices evaluated is shaped like a corkscrew and wraps around about 2 feet of power line. Another diverter resembles a perforated fluorescent pie plate with a reflective center. The third is about the size of an envelope, with reflectors attached and flaps in the wind.

The study couldn’t determine how well they worked.

“These things may have helped but it’s hard to say how much,” Wilkerson said. “What we did learn is that it’s still a real dangerous place for birds.”

Wildlife officials collected nearly 1,170 avian carcasses along the causeway during a three-year period beginning in 2006. About 100 species were found, including seven piping plovers, a threatened shore bird.

Wilkerson said 140 birds were killed in collisions with power lines in 2006 when no diverters were used. In 2007, 104 bird deaths were attributed to power line strikes after hundreds of the devices were attached to the wires. Power lines killed 86 birds in 2008, he said.

While the power line strikes appeared to shrink after the diverters were in place, the study raised questions, including whether the birds were being forced lower, making them susceptible to vehicle strikes, Wilkerson said. About 580 birds were killed by vehicles on the causeway from 2006 to 2008; the cause of death for about 260 other birds couldn’t be determined.

“There’s a whole bunch of theories but there is not enough stuff in this study to help sort it out,” Wilkerson said.

Power lines along the causeway are linked by 11 spans. The diverters were placed only on power lines in selected spans, with some wires left bare to compare results. The diverters were moved to different locations during the study to compare them against each other.

“It’s really hard to say which ones worked where and why,” Wilkerson said. “Statistically, they didn’t see a difference between marked spans and unmarked spans.”

Biologists have said the North Dakota study is valuable because it’s on the Central Flyway migration corridor and between two large water bodies. It was hoped that lessons learned from the project could be applied to other areas where there are many bird deaths.

Studies done in the past have proved the effectiveness of bird diverters, said Terry Ellsworth, a Bismarck biologist for the U.S. Fish and Wildlife Service, which helped in the project.

Ellsworth said his agency had not seen the results of the latest study.

“I think it’s an issue with statistics,” Ellsworth said. “I’m sure they help. Putting up markers is not 100 percent effective, but they definitely reduce mortality.”

Bird diverters are still attached on some spans along the causeway. Ellsworth said his agency will ask WAPA to install them on all spans.

Diverters cost between $8 and $40 and last from a year to two decades. Burying the power lines would solve the problem but is too expensive, Ellsworth and Wilkerson said.

Bird deaths have increased in the area with dozens of electric-generating wind towers that have been constructed in the past few years, Ellsworth said. A study of those deaths is underway.

Biologists are most worried about rare whooping cranes that pass through the area in the spring and fall on their way to Canada or Texas. The birds are considered one of North America’s most endangered.

The Fish and Wildlife Service has said that wind farm owners have private biologists on site during the big birds’ migration. The spinning turbines are stopped if a whooping crane is spotted.

No whooping crane deaths have ever been reported in the area, either from power lines or wind turbines, Ellsworth said.

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