Researchers at the Norwegian Institute for Nature Research tested a surprisingly simple method for reducing bird collisions at the Smøla wind farm in Norway: painting one of a turbine’s three rotor blades black. Four turbines received the treatment while four neighboring turbines remained unchanged as controls.
The results, published in Ecology and Evolution in 2020, were striking. Researchers calculated that the annual bird-fatality rate at turbines with a black blade decreased by an average of 71.9% relative to the neighboring control turbines. NINA summarizes the result as roughly a 70% reduction.
The idea is that increased visual contrast may make rotating blades easier for birds to detect. When identical light-colored blades rotate quickly, they can become harder to distinguish visually; adding a contrasting blade may reduce this effect and give approaching birds more opportunity to avoid the rotor.
However, the Norwegian experiment involved only four painted turbines, so researchers cautioned against assuming the same reduction will occur everywhere. Other projects have therefore been testing the technique in different landscapes and with different bird species to determine how broadly the approach can work.
