Duke Energy Renewables Inc., a unit of utility Duke Energy Corp., last month pleaded guilty to violating the federal Migratory Bird Treaty Act at two of its wind projects in Wyoming. The company agreed to pay $1 million in fines and restitution in the deaths of 14 golden eagles and 149 other protected birds.
A study earlier this year by researchers at the U.S. Fish and Wildlife Service found 85 eagles had been killed at 32 wind farms across the country from 2007 to 2012. None of the reports were from wind farms in Oklahoma. Researchers excluded eagle fatalities at California's Altamont Pass, a notorious site for eagle deaths from the many wind turbines installed along a ridge.
Separately, researchers at Oklahoma State University, the Smithsonian Institution and the U.S. Fish and Wildlife Service recently published a paper looking at all bird fatalities linked to large wind turbines. On average, about 234,000 birds are killed annually by collisions with turbine monopoles, their research estimated.
“We found support for an increase in mortality with increasing turbine height and support for differing mortality rates among regions, with per turbine mortality lowest in the Great Plains,” said Scott Loss, assistant professor at OSU's Department of Natural Resource Ecology and Management.
Loss's wind turbine paper was the second in a series on bird mortality. The first study estimated outdoor cats kill between 1.4 billion and 3.7 billion birds each year in the United States.