Painting one wind turbine blade black reduces bird mortality

"Researchers in Norway found that changing the color of just one turbine blade from white to black resulted in a 70% drop in bird deaths. The effect was strongest among raptors.

The study, published in Ecology and Evolution, followed up on previous lab experiments." ref.

This is because the black blade provides a high-contrast visual cue that makes the spinning blades more visible to birds, particularly raptors, reducing a phenomenon called "motion smear" where birds cannot track the fast-moving, monochromatic blades. In one Norwegian study, this intervention resulted in a greater than 70% reduction in bird mortality."