Wind energy is a valuable tool for addressing the climate crisis, but wind turbines can be deadly for birds. A recent study found that a low-tech, relatively inexpensive fix can dramatically reduce bird collisions with turbines: A can of paint.
When wind turbines rotate their massive white blades can become a transparent blur, making them difficult to discern for birds, a phenomenon known as a motion smear or motion blur. Breaking up that blur, by painting one blade a different color, can theoretically make the turbine more visible to birds so they can navigate around the deadly blades.
Researchers recently reported results from a long-term experiment that did exactly that: Between 2020 and 2021, Acciona Energía, owner of El Ruedo wind farm in Cadiz, Spain, painted one of three rotor blades black on four of its turbines. Another 16 turbines had all white blades and served as controls. Every day, from 2012 to 2024 (before and after the turbines were painted), they looked for dead birds under all 20 wind turbines and recorded their data.
The researchers found that annual bird fatality rates dropped by nearly 74% for the painted turbines compared to the controls.
The Spanish study joins others that have found similar results. A study in Norway found a more than 70% drop in annual bird fatalities after turbines had one of their blades painted black, while a South African study found bird deaths decreased by 83% after painting one of the three blades red. However, a study in the Netherlands found painting the blades showed no significant reduction in bird deaths.
In the U.S. alone, up to a million birds are killed by wind turbines each year. While significant, that number pales in comparison with the billions of birds killed by cats, and another billion killed by building collisions each year in the country.
As the world turns to renewable energy to address climate change more wind development could cause more bird deaths, according to study lead author Roel May with Norwegian Institute for Nature Research (NINA). That’s especially significant for birds that are most vulnerable to windmills including migrating songbirds and “many long-lived raptors and other soaring birds,” May told Mongabay in an email. “Those species often have long lifespans and low breeding rate and are therefore especially vulnerable to additional mortality from a population perspective.”
The blades in the Spanish study were painted after the turbines were already up and operational, which is challenging and expensive. Painting blades during manufacturing is easier and cheaper, but manufacturers have been hesitant, citing concerns that black paint could cause blades to heat up more easily or alter their weight, May said.
Testing the efficacy of painting turbine blades to reduce bird deaths has so far been done at small scales, he said. However, May hopes the industry will scale up the low-tech solution, monitor its success and “learn by doing.”
Banner image: Wind turbines in Wyoming, U.S. Image courtesy of USGS.
