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article imageNew evidence for wind turbines posing risks to birds

By Tim Sandle     Oct 1, 2016 in Environment
San Fransisco - Wind turbines have many advocates as a low-cost source of ‘green’ electricity. However, depending on where the turbines are cited, there is a risk of birds being killed.
Earlier reports have shown wind turbines to present a risk to large birds, like golden eagles in the United States. A new report suggests that birds found hundreds of miles are at risk.
To ascertain the impact, scientists from Purdue University have gathered tissue samples from golden eagle bird feathers and extracted DNA. The birds were killed close to the Altamont Pass Wind Resource Area in northern California. Through the additional use of isotopes, it was shown that the fallen eagles were not only those that resided nearby, some of the eagles had come from hundreds of miles away. By studying the eagle feathers for stable hydrogen isotope, scientists can calculate where the eagle grew its feathers.
Variations to the molecular weight of the isotope gives an indication to the location, especially in comparing birds that reside inland to those that are near the ocean. Such analysis can be supported by DNA testing, where different populations of eagles have different gene pools.
The new study found that 75 percent of dead eagles lived local to the turbines but some 25 percent were birds that have travelled long distances.
The site in California is large, consisting of 5,000 turbines. It has long been a concern of conservationists that the turbines kill an excessive number of larger birds, together with bats.
With the risk to eagles, lead researcher Professor J. Andrew DeWoody explains in a research note: “Eagles tend to use that habitat around the turbines. It's windy there, so they can save energy and soar, and their preferred prey, California ground squirrels, is abundant there.”
Due to the flight path many eagles take, and due to their predatory focus towards ground level, eagles often do not see turbine blades.
The work is of ecological importance since golden eagles are threatened species. Knowing the population risks from human-led buildings and machinery, including wind turbines, feeds into vital conservation work.
The research has been published in the journal Conservation Biology. The paper is titled “Golden Eagle fatalities and the continental-scale consequences of local wind-energy generation.”
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