Bird deaths from wind turbine’s drop by 72 per cent when one blade is painted black

Painting one blade of a wind turbine makes it easier for birds to avoid a deadly encounter. 

A study found that painting one of the four white blades on a wind turbine black reduces the amount of dead birds by 72 per cent. 

Scientists from the Norwegian Institute for Nature Research conducted a trial on the remote island of Smola comparing how many birds were killed by four painted turbine compared to their untouched neighbors. 

Scientists regularly scoured the bottom of the turbines with specially trained sniffer dogs to identify any bird carcasses. 

This was done for seven and a half years before the blades were painted and three and a half years after treatment.  

For the eight turbines included in the research – four painted and four left bare –  a total of 1,275 searches were conducted between 2006 and 2016. 

A total of 82 carcasses were found and statistical analysis revealed the birds which benefit the most from the pained blades are raptors and large soaring birds. 

This includes eagles and vultures, who have been high-profile casualties of wind turbines. No white-tailed eagle carcasses were recorded after painting the blades.

Kestrels, snipe and golden plovers also benefited from the experiment.  

Six white-tailed eagles, which have an impressive 8-ft wingspan, had been killed by the turbines before they were painted, but none were recorded after the treatment.   

Estimates from a 2014 study by the London School of Economics predicts there could be up to 106,000 bird deaths a year as a result of UK wind turbines. 

It also found that while the number of dead birds dropped at painted turbines, it did not trigger a spike in the amount of casualties at neighboring sites. 

Researchers suggest the reason painting a single blade works is due to a phenomenon called ‘motion smear’. 

This means that, although birds often have exceptional eyesight, the rotating blades appear invisible.

Birds have extremely high-resolution eyesight in their peripheral field of vision, and the front-facing eyesight is not as good.  

The study said: ‘Within an assumed open airspace, birds may therefore not always perceive obstructions ahead thereby enhancing the risk of collision.’

The findings are published in Ecology and Evolution.