Painting wind turbine blades with warning colors could reduce bird deaths

A new study by the University of Helsinki suggests that using natural warning colors on wind turbine blades may help prevent birds from colliding with the structures. The experimental research, published this week, found that patterns mimicking nature’s warning signals—such as black, red, and yellow stripes—were the most effective in deterring birds.

In the study, great tits were first trained to peck at gray spots on a computer screen in exchange for food. Researchers then introduced digitally rendered wind turbines with different color patterns alongside the gray spots. The black-red-yellow striped blades caused the strongest avoidance reaction in the birds, significantly more than the single black blade currently used in Norway or the red striping employed in Germany. Plain white blades, the current standard, had the least effect on bird behavior.

“Warning colors are deeply ingrained in their genes,” explained Johanna Mappes, a professor at the University of Helsinki. “Birds instinctively avoid them in many different contexts.” While further real-world testing is needed—including studies on how birds adapt to the colors over time and tests with other species—Mappes described herself as “reasonably optimistic” that the principle would work in natural settings.

Wind turbines pose a growing threat to declining bird populations, though they are not yet the leading cause of bird fatalities—windows and domestic cats still claim far more lives. However, as green energy expansion accelerates, collisions with turbines are increasing. “Global bird populations are plummeting,” Mappes noted. “Every unnecessary death weakens already struggling species.”

Petteri Mäkelä, environmental manager at Hyötytuuli Services—a company involved in projects like the Tahkoluoto offshore wind farm in Pori—welcomed the findings. He suggested that colored blades could be implemented in new turbines with minimal additional cost. The approach might be particularly effective for reducing collisions with white-tailed eagles, which frequently strike the blades. For grouse and other forest birds, however, the greater risk comes from flying into the light-colored towers, as their forward vision is poor and they may misinterpret the structures as gaps in the forest.

Mäkelä cautioned that overly bright colors could also backfire by scaring birds away from feeding areas even when no immediate collision risk exists. Current Finnish aviation laws mandate white blades, and the National Board of Antiquities prefers light-colored turbines to minimize landscape disruption. Mappes hopes future research could identify color schemes that deter birds while remaining visually acceptable to humans.

Despite the potential of colored blades, Mappes stressed that avoiding critical bird habitats and migration routes remains the most effective way to prevent turbine-related bird deaths.