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Painting a wind turbine blade black can reduce bird collision by 70%

New research for the first time has provided concrete evidence that painting one wind turbine blade black can significantly reduce the collision of birds, in particular raptors. The researchers, from Norway and Sweden, say if further assessments continue to be as successful, blades should be painted before turbines are assembled.

Laboratory experiments have previously indicated that painting one of three rotor blades black minimises so-called motion smear, where birds don’t see the turbines moving. But the new study, conducted over a 10 year period, proved the concept in reality.

The study, conducted at the Smøla wind‐power plant in Norway, found the annual fatality rate was reduced by an average 71.9% at the turbines with a painted blade, relative to unpainted turbines on the same site, enabling birds to take evasive action in due time.

The treatment had the largest effect on reduction of raptor fatalities; no white‐tailed eagle carcasses were recorded after painting, and significantly reduced the collision risk for a range of birds.

While wind energy provides one solution to the climate emergency, as the scope and scale of wind power plants increase, wildlife and habitats can suffer, along with the communities living there. Birds, in particular, cannot easily see the wind turbines blades, mostly when in motion, which can lead to collisions and subsequently, mortality.

The ideal scenario for birds is for wind farms to be located away from major migration routes and important feeding, breeding and roosting areas of those bird species known or suspected to be at risk.

To date, very few measures have been developed to reduce the risk of collision. Those that have been recommended, such as selective shutdown along a migratory flyway for soaring birds and tilling the soil around the tower base come at a cost, either through revenue loss or annual habitat management respectively.

Given the resource intensity of painting while the turbines were already in place, the researchers recommend manufactures paint rotor blades before construction of the turbines. They do, however, recommend repeating “this experiment at other sites to ensure that the outcomes are generic at various settings”.

Eight wind turbines were used for the study and a total of 1,275 individual turbine searches were performed from 2006-2016, during which 82 carcasses were found (including 40 willow ptarmigan not included in the study). The paper was published in Ecology and Evolution by researchers from the Norwegian Institute for Nature Research, Norway, and the Lake Ånnsjön Bird Observatory, Duved, Sweden.

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