Smøla, an island off the northwest coast of Norway, is home to a wind farm where white turbine blades spin in wide, steady arcs against a pale sky while the air moves continuously. It’s a tidy and useful location, the type of renewable energy installation that climate activists gladly cite. However, shortly after it opened in 2002, something continued to occur. White-tailed Eagles were dying as they flew into the blades. No one could quite figure out why a bird with extraordinary vision, able to see a fish from a hundred meters above the ground, was unable to see a small building-sized structure spinning in front of it.
For years, Roel May, a researcher at the Norwegian Institute for Nature Research, worked to find the answer. His final working theory, which has been adopted by other scientists, is based on a concept known as motion smear. Turbine blades no longer resemble solid objects when they rotate quickly enough. Particularly when the sky is light gray or white, they blend into the background. The blur is not perceived as a threat by a bird. It interprets it as empty air, or maybe it doesn’t. There won’t be time to alter direction by the time the blade transforms into something recognizable.
May and his group made the almost embarrassingly simple decision to paint one of the three blades black. An old, unpublished report from a U.S. energy research lab served as the inspiration. The idea was that a single dark blade would disrupt the blur, break the visual homogeneity, and provide birds with a solid object to perceive and respond to.
They were granted a loan of four turbines by the Smøla operators. Only four turbines could be painted due to the high cost and complexity of the process, which involved a team of skilled painters rappelling down onto the blades while they were stationary. As the comparison group, four more were left unpainted.
Trained dogs and personnel patrolled the site to look for carcasses both before and after the paint job for a total of more than ten years. The number of bird deaths at the treated turbines decreased by more than 70%. In particular, the number dropped to zero for white-tailed eagles. The study, published in the journal Ecology and Evolution in 2020, was careful not to oversell the findings — the sample size was small, the number of recovered carcasses modest, and the researchers themselves noted that results might vary by location and species. However, a 70% decrease is a figure that is difficult to overlook.
It makes sense that some people might have been skeptical due to the solution’s simplicity. Radar systems, GPS tracking, acoustic deterrents, and automated shutdown technology are all part of the world in which the wind energy sector operates. It seems almost too easy to think that a gallon of black paint could do better than any of that. Even though the results were encouraging, Roel May wrote that this was “surely not a golden egg solving all bird-collision problems in the world.” The lead researcher’s candor likely contributed to the study being taken seriously rather than written off as an anomaly.
How well the method adapts to various environments is still unknown. Researchers from Oregon State University are currently conducting a replication study at a PacifiCorp wind farm close to Glenrock, Wyoming. There are twenty-eight black-painted blades. Using an existing dataset of eight million recorded flight points, the OSU team is tracking golden eagle movements and incorporating altitude data—three-dimensional modeling that was never attempted in the majority of previous studies. Given that bats primarily use sound to navigate and may not even benefit from the visual cue, it is also being investigated whether bats react differently to visual changes.
The U.S. Fish and Wildlife Service estimates that the wind energy industry in the country kills between 140,000 and 500,000 birds every year. That figure is at odds with the justifiable environmental benefits of shifting away from fossil fuels. The industry hasn’t found a clear solution to this conflict, and painting turbines black won’t make it go away either. Similar studies are being conducted in South Africa, Sweden, and Spain. When the results are obtained, they will be significant.
There is an additional regulatory complication in the United States. Because of issues with aircraft visibility at night, the FAA currently forbids painted turbine blades. Regardless of what the science indicates, the approach isn’t yet deployable at scale here, but it hasn’t said no definitively—a spokesperson said there is a process for reconsidering such rules. That’s a frustrating gap between evidence and policy, though not an unusual one.
At the very least, the Smøla experiment demonstrated that technology isn’t always the only way to address the issue of bird collisions at wind farms. Sometimes the solution is more perceptual than mechanical; it involves making something that was previously effectively invisible visible. The Wyoming data, regulatory flexibility, and whether wind companies determine that the cost and logistics are worthwhile at scale will determine whether painting turbines black becomes industry standard practice or stays a regional experiment. For now, four turbines on a Norwegian island still have their black blades turning, cutting dark arcs through the sky, and the eagles there seem to be giving them a wide berth.
