As SCA and Norway’s Statkraft apply for approval to build wind farms in northern Sweden, the companies are also keeping a careful eye on birds-of-prey. The windy locations suitable for wind turbines are also favoured by golden eagles.
Bengt-Göran Carlsson is one of a number of biologists enlisted to find out if there are breeding eagles in the areas and, if so, to pinpoint their nesting sites.
“You have to constantly scan the horizon. It’s easiest to see the eagles when they’re against the sky, but we really want to see where they fly up from so we can work out where they’re nesting,” Carlsson says.
The eagle survey took place between February and October 2008; all areas were visited at least three times prior to the nesting season.
“Golden eagles are easiest to observe in late winter and early spring, before they start to mate,” Carlsson says. “At this time, each pair displays to each other and flies around like yo-yos, diving from great heights and then soaring upwards again.”
Nest sites found
The eagle-watchers scan the skies from carefully chosen vantage points, for five to six hours at a time. When they see an eagle, they note the time, coordinates, the direction the bird takes and the length of the observation. Carlsson then inputs the data into GIS computer software that enables him to track the eagles’ movements and the size of their territories.
“This helps us to work out if there might be a nest site in the area,” he says.
During May, Carlsson and several other colleagues used helicopters to survey the areas for possible nesting sites. They also explored the territories on foot. When the areas were revisited in August the teams were able to log various breeding attempts, including one that resulted in fledglings.
“There needs to be a protection zone around every nest site so the eagles can have peace and not be disturbed by wind turbines or power lines,” Carlsson says.
Biologists and eagle experts say that these zones should have a radius of two kilometres, though some Swedish municipalities think one kilometre is enough. In some cases the regulatory authorities have to decide if a location can be deemed a non-breeding area or if wind turbines should be moved to protect resident eagles. Artificial nest sites have been used successfully in some parts of Sweden to persuade
eagles to nest away from a wind farm.
Dangerous rotor blades
No one knows exactly how wind farms affect golden eagles, but the main risk is that the birds could collide with the rotor blades of a turbine. An extensive study in Scotland prior to construction of one wind farm looked at subsequent changes in the birds’ behaviour. The results revealed that the birds did indeed alter their habits and movements. In some cases, wind farms have caused more serious problems. Fatal collisions involving white-tailed eagles are a problem at a wind farm on the Norwegian island of Smöla off the coast of Trondheim. A wind farm comprising 6,500 turbines at Altamont in California has had an adverse affect on the local population of golden eagles.
“Because we don’t yet have any largescale forest wind farms, we don’t have enough knowledge about the effects of such projects,” Carlsson explains.
License applications for the six wind farms were submitted at the end of 2008. The observations of the eagle watchers were included in the environmental impact assessment survey for each wind farm.
“In the application, we recommend that our wind farm control programme should monitor how the golden eagles are affected by the turbines,” says SCA project manager Åke Westberg. “That will help give us information that may be valuable in the future.”
Carlsson adds: “Eagle watchers like me are in support of the wind farms, and agree that these are good areas for wind power. We just want to make sure that measures are taken to protect the eagles.”
Source Shortened article from Papergram 2/2009 More information www.vindkraftnorr.se