On Birds and Windmills

A wind farm on Kelsey Peak in northern New Hampshire. Photo by Clinton Parrish.

For those concerned about climate change, renewable energy development is a nobrainer. And the breezy mountaintops of New England, far from human population centers, appear to be ideal settings for wind turbines. But there are plenty of nonhuman populations that could be affected, few of which have been evaluated.

A new study by a Plymouth State University graduate student is the first to examine what happens to high elevation bird populations when their habitat is disturbed by the installation of a commercial wind farm. Clinton Parrish used the Granite Reliable Wind Park in northern New Hampshire, a development of 33 turbines, each about 410 feet tall, as his study site. He was most interested in learning how well the rare Bicknell’s thrush fared, a bird that nests exclusively in the mountains of the Northeast.

“I was trying to see if the wind farm influenced their habitat use, if they would exhibit avoidance of the turbines, and if, over time, we could detect a reduction in their abundance,” Parrish said.

Focusing on the area around the 15 turbines between Dixville and Kelsey peaks, he compared the differences in thrush numbers in 2010 before the wind turbines were built, during construction in 2011, and again in 2012 when the wind farm was operational. The good news was that Bicknell’s thrush abundance remained relatively stable from year to year, and the birds did not appear to avoid the turbine pads and access roads. When the turbines were operational, however, the birds nesting closest to the turbines expanded their home ranges.

“We think that was perhaps an indication that they have to move more to compete with the masking noise of the turbines, so they can effectively broadcast their song,” Parrish said.

While this study did not find significant changes to the Bicknell’s thrush population, Parrish found changes in the abundance of other bird species. Birds that prefer to nest in the forest interior, including gray jays, golden-crowned kinglets, and black-backed woodpeckers, declined in numbers, while species that prefer more open habitat, like fox sparrows, dark-eyed juncos, and blackpoll warblers, all increased. The biggest change was in the number of American robins, which prefer habitat at the forest edge. In 2010, Parrish found no robins in his study area, but large numbers moved in as soon as turbine development began.

Parrish expects further shifts in species populations in the coming years, including Bicknell’s thrush. “Neotropical migrants like Bicknell’s thrush have a strong site fidelity, so they will likely breed in the same place they’ve been before, regardless of how it may have changed,” he explained. “But we may well see changes in the next generation. The habitats adjacent to the turbines may be less preferable, so the birds may shift away from them. And as species that prefer edge habitat move in, like robins and other thrushes, that may increase competition and also cause them to move away.”

The owner of the wind farm has agreed to do a follow-up study of bird populations in five to ten years.

 
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