Painting a blade of a wind turbine black could reduce bird strikes in wind farms by up to 70%, according to a study.
Birds that collide with structures have long been considered one of the main negative impacts of onshore wind farms, the authors observed.
The RSPB welcomed the research, but said the priority remained to avoid placing wind farms where there was a risk to wildlife, such as birds.
The results were published in the journal Ecology and Evolution.
“The collision of birds, especially raptors, is one of the main environmental concerns in the development of wind power,” observed co-author Roel May.
“In Norway, 6-9 white-tailed eagles are killed each year at the Smøla wind power plant; it provoked opposition and conflict. ”
The Smola wind farm is located on the west coast of Norway, consisting of 68 turbines over 18 square kilometers, making it one of the largest onshore wind farms in Norway.
Paint it black
Dr May, a senior researcher at the Norwegian Institute for Nature Research in Trondheim, said the team wanted to test whether mitigation measures could reduce the rate of bird collisions.
“One of the mitigation measures we tested was to paint one of the three rotor blades black,” he told BBC News.
“This design is expected to reduce what is known as motion smear, making the slides more visible to birds.
Dr May said the concept of smear reduction of rotating blade movement was based on laboratory experiments conducted in the United States at the turn of the century.
The authors observed: “The annual mortality rate was significantly reduced in painted vane turbines by more than 70% compared to neighboring control turbines (ie unpainted).”
Dr May said the results were encouraging but further testing at different wind farms was needed in order to make the results more robust.
He observed: “While we have seen a significant drop in bird collision rates, its effectiveness may well be site and species specific.
“At the moment there is interest in performing tests in the Netherlands and South Africa. ”
Martin Harper, RSPB’s conservation director, praised the research, but said it was important to remember that wind farm development should “happen in harmony with nature”.
“Wind turbines are the right technology when we find the right places for them, so studies like this are invaluable and build on our understanding of additional mitigation measures that could be used once we have identified locations. suitable for wind farms, ”he said.
“As the report acknowledges, this studied only one site and more work needs to be done, so we would be interested in seeing more research in this area. “
Meanwhile, a spokesperson for manufacturer Siemens Gamesa said the issue was an issue for developers and wind farm operators to consider, rather than manufacturers.
He told BBC News: “We are not involved in the ongoing management of a wind farm, so we are not familiar with bird strike cases. ”
But he added: “We could manufacture according to specifications defined by the developers. ”
A spokeswoman for ScottishPower Renewables, which operates the UK’s largest onshore facility – the 539 MW Whitelees Wind Farm in Scotland, described the study as “a really interesting development”.
She said: “Our approach to wind farm development takes into account the local bird population from the start. ”
“This includes careful planning to make sure we pick the right locations in the first place; and we also work closely with RSPB and Scottish Natural Heritage to ensure that we are doing all we can to protect local wildlife. ”
Dr May said he would like to see wind farm developers adopt mitigation measures, such as the painted blade, where bird strikes have been proven to be a problem.
“If this is done before construction, it will be a very cost effective measure that can help reduce unnecessary conflict,” he added.
“What has not yet been tested is whether other models of rotor blades (for example, the red blade tips used to warn aviation) could be just as effective.
“Any improvement (or co-benefit) in the design could be of interest for further study. However, this does not exclude the implementation of the current design. “