CLEANTECH: Avoiding Bird Collisions with Power Lines

By Published On: August 21, 2009

Strange curly-cued objects on power lines in the San Luis National Wildlife Refuge are visible to visitors of late. They’re part of a just concluded study for the California Energy Commission, which showed these simple devices--so-called “diverters”--could help prevent birds from slamming into power distribution lines. Biologists estimate that millions of birds die each year after colliding with power lines. U.S. Forest Service scientist Albert Manville estimates power lines may kill as many as 175 million birds a year in the U.S. Conducted by the Salinas-based Ventana Wildlife Society, the study showed that diverters cut the frequency of bird collisions with power lines by up to 48 percent compared to nearby lines without diverters used as experimental controls. The researchers thus recommended that the diverters be installed on a wide scale in the refuge area. Researchers placed diverters on some of the 36 miles of lines that run near the wetland area, which serves as a major resting place for millions of birds. Biologists then observed lines--both with and without diverters--and counted casualties. They tallied bird carcasses under the lines too. Observations covered two winters between 2006 and 2008. Most of the carcasses researchers found were American coots, a night flying bird. To protect the coot and other birds that fly at night, the researchers recommended using illuminated diverters in the area, although they are not yet common. The results of the study can be generalized, said Kelly Sorenson, Ventana Wildlife Society executive director. However, he noted that the type of diverter needed and their placement should vary by location as dictated by localized bird species. “We need to be more strategic,” said Sorenson, when it comes to protecting birds. He advocated focusing protective measures solely in areas home to large bird populations. “I would suspect that 80 percent of the fatalities are caused by 20 percent of the lines,” he said. In the San Luis study area, the diverters appeared to alert birds to the presence and location of distribution lines and give them added time to change course, according to the study entitled Evaluating Diverter Effectiveness in Reducing Avian Collisions with Distribution Lines at San Luis National Wildlife Refuge Complex, Merced County, California. Ventana performed the study, released August 19, for the CEC, Pacific Gas & Electric, and Edison Electric Institute. Researchers tested two brands of diverters--the Bird-Flight DiverterTM and the Swan-Flight DiverterTM. The Bird-Flight Diverter cut collisions by 48 percent and the Swan-Flight Diverter by 38 percent. Both devices are made of polyvinyl chloride and look like short, coiled sections of wire that are wrapped around the power lines. Cleveland-based Preformed Line Products makes the plastic diverters for use on distribution lines, plus a heat resistant aluminum diverter for use on higher voltage transmission lines, said Bob Peterson, company technical support representative. Business has been picking up, said Peterson, as more utilities become concerned with protecting wildlife. The diverters, said Sorenson, are “dirt cheap,” but installing them can be difficult. He noted that PG&E installed some around Big Sur by dangling crews from helicopters above power lines because the terrain prohibited easy access from the ground. In other cases where access with utility trucks is limited, lines must be dropped to install the devices, Sorenson noted. However, it is inexpensive to install the devices when a truck outfitted with a lift can drive up right under the lines.

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