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A  year ago, a Golden Eagle approaching the Glenrock/Rolling Hills wind farm in Wyoming might have seen a dangerous optical illusion: A turbine’s blades, spinning at more than 150 miles per hour, would appear not as solid objects to be avoided, but as a blur the bird could fly through. Scientists believe this disorienting visual phenomenon, known as motion smear, contributes to the collisions that kill an estimated 140,000 to 679,000 birds per year at wind farms in the United States. 

The same eagle soaring over the area’s scrubby sagebrush today will see warning signs. Those once indistinct and innocuous-seeming blurs will present clearly as physical masses, signaling to birds that they should steer clear. 

Such is the hope, anyway, of a study now testing a surprisingly simple tool for making wind farms less hazardous to birds: black paint. This summer, PacifiCorp, which owns the facility, aims to finish painting one blade on each of 36 turbines there. Over the next several years the company and its partners, including the federal government, will keep track of how many eagles and other daytime-flying birds those turbines kill compared to their previous toll and to the remaining 100 or so that have not been painted. Search teams will look for eagle carcasses, while specially trained dogs will sniff out other birds and bats. “We’re trying to have as little impact as possible while also trying to provide electricity to customers,” says Jona Whitesides, a spokesperson for PacifiCorp.

Depending on its outcome, the research may help to crack a difficult environmental conundrum. On one hand, capturing more wind power is a core tactic for addressing climate change, which Լ����Ƶ science shows threatens two-thirds of North American bird species with extinction. “In order to conserve our birds and protect our birds, we have to have wind energy,” says Garry George, Լ����Ƶ’s senior director of climate strategy. The Biden administration has set a goal of a carbon-free electric sector nationwide by 2035, and a Department of Energy analysis shows that getting there may involve more than quadrupling the installation rate for wind turbines. At the same time, placing all those additional spinning blades on the landscape increases the odds of more birds dying from collisions. If painting turbine blades proves effective, it will offer a low-tech, low-budget way to reduce harm.

There’s good reason for optimism. In 2003 the National Renewable Energy Laboratory from a lab study of American Kestrels suggesting that painting a single blade black could protect birds by cutting down on motion smear. The report recommended that scientists test the idea in the field. A team in Norway answered that call and published a paper in 2020 showing a 72 percent reduction in avian fatalities at a small wind farm on the island of Smøla. “That really lit things on fire,” says Robb Diehl, leader of the Wyoming project’s science team and an ecologist with the U.S. Geological Survey. 

Encouraging as it was, the Norway study had limits. It mainly involved birds that fly during the day, but many collisions happen at night, when a black blade may not stand out. It was also quite small, with just four painted turbines out of eight. Efforts to gauge how many birds a paint job may help are happening around the world, from South Africa to the Netherlands. Diehl believes the Wyoming project is the largest.

For PacifiCorp, there’s a lot riding on the outcome. In 2015 it paid millions of dollars in Migratory Bird Treaty Act penalties for killing hundreds of birds, including at least 38 Golden Eagles, at Glenrock/Rolling Hills and another Wyoming site. The new research is part of the company’s broader strategy to prevent further deaths, which also involves selectively slowing or shutting down turbines when birds are observed nearby.

Others, too, are closely watching to see what happens. The project partners include two large energy companies, Oregon State University, and the nonprofit Renewable Energy Wildlife Institute, which aims to reduce the industry’s impacts on animals. If the test in Wyoming is as successful as the one in Norway, turbine blades across the country could soon get a fresh coat of paint. 

This piece originally ran in the Summer 2024 issue as “Test Pattern.” To receive our print magazine, become a member by .