Monitoring of the protected birds of prey, which nest near the 65-turbine Beinn an Tuirc wind farm in Argyll, has shown the scheme has had no adverse impact on their survival and breeding.
The study began in 1997, ahead of construction of the wind farm, after scoping work for developer ScottishPower Renewables identified the Kintyre site as a nesting territory for Scotland’s unofficial national bird.
The energy firm minimised potential risks to the eagles by erecting the turbines further south than was originally planned and clearing a forestry plantation to create more favourable moorland habitat to the north.
Work was also done on 1,800 hectares of land to control livestock grazing and encourage wildlife prey such as red grouse to flourish.
Now senior ecologists have confirmed the pair of golden eagles resident there are among the most successful breeders in the region and the 100m-high turbines appear to have had no ill effects on their existence.
The same female golden eagle has occupied the Beinn an Tuirc site since monitoring began, and was joined by her current mate in 2007.
She had laid eggs with a previous mate but none had ever hatched. However, six chicks have successfully fledged since 2008.
Peter Robson, the energy firm’s senior ecologist, said: “We’ve been able to demonstrate how you can plan a wind farm in an area where there are sensitivities. In this case we were able to identify how the golden eagles used the territory and design the wind farm so it didn’t overlap with that range.
“The only way they can raise two chicks in a year is if they have an abundance of food, so our priority was to make sure they had that.
“Our monitoring has confirmed our assumption that they wouldn’t go over the wind farm. That’s the main learning point from it.
“In the 15 years since the turbines have been operating there have only been two observed flights of an eagle over the wind farm, and that’s out of thousands.
“We’re very confident that the amount of time they spend over the turbines is incredibly small.”
Conservationists have welcomed the report, pointing out that the research has provided valuable information that will help understand the impacts of onshore wind on wildlife and inform the planning process for future renewable energy projects.
Aedan Smith, head of policy and development for RSPB Scotland, said: “Beinn an Tuirc has been operating for quite a while now – it’s one of the longest-running onshore wind farms in Scotland. When it was first proposed we were initially quite cautious because it was so close to golden eagle territory.
“But ScottishPower Renewables have really shown a lot of commitment to it from the outset, and did a lot of work to try to create alternative habitat for the golden eagles, which is really useful, but also implemented this monitoring project.
“But this is also a good illustration of how important it is for companies to invest in nature conservation when there is likely to be an impact on the natural environment and ensure that any adverse effects are mitigated.”
He added: “This study is a good example of a wind farm operator taking its responsibilities to the surrounding wildlife seriously, and we need to see more long-term studies of this sort taking place at operational wind farms across Scotland.
Ecologist Iain Mackenzie of Natural Research Projects, which carried the monitoring work for ScottishPower Renewables, said: “This has been a fascinating project to work on over the last 20 years.
“We’ve learned much about how golden eagles interact with wind farms, and the project has highlighted how careful planning can allow renewable energy projects to co-exist positively with upland wildlife.
“Chicks fledged from near the Beinn an Tuirc wind farm are helping to ensure that these iconic birds continue to occupy the Scottish uplands.”