Oregon researchers paint wind turbines partly black to reduce bird deaths

A wind turbine with one blade painted black at a PacifiCorp wind farm in Wyoming. (Oregon State University)

A simple coat of black paint on the white blade of a wind turbine could save countless birds from flying into the machines and to their deaths each year.

It’s working in Norway, and now researchers from Oregon State University are trying it in the West. With $400,000 allocated by the state Legislature, Christian Hagen, an associate professor in the university’s Department of Fisheries, Wildlife and Conservation Sciences, is leading a team that’s painting turbines at a PacifiCorp wind farm in Wyoming. A doctoral student and officials with the  U.S. Geological Survey, U.S. Fish and Wildlife Service and U.S. Department of Energy are collaborating on the project.

Studies show that wind turbines kill anywhere from 140,000 to nearly half a million birds each year, in addition to the hundreds of millions killed each year by flying into buildings or by house cats.

A study from Norwegian researchers published in 2020 in the journal Ecology and Evolution found painting one of the three blades of a wind turbine black reduced bird mortality by more than 70%. Researchers found that birds – especially birds that hunt from high in the sky such as eagles, hawks and other raptors – experience “motion smear” that prevents them from seeing a fast moving, monochromatic object up close. They don’t see it because their retinas can’t keep up with the velocity of the blade. With one blade painted black, it creates a contrast between the blades, increasing visibility and reducing the motion-smearing effect, researchers found.

Since December 2023, the OSU and PacifiCorp team has added black paint to 28 turbines and plans to finish painting eight more this year. In a news release, Hagen said the Norwegian study used a smaller sample size and that the researchers wanted to see whether they could measure the effect on a larger variety of birds as well as bats by painting more turbines.

“Industry and scientists in North America felt that before this became a policy change, we should replicate, enlarge the sample size and analyze different bird species to ensure it is effective, and that there aren’t any negative effects,” he said.

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