Turbines vs. eagles debate continues amid new science

Source: Michael Doyle, E&E News reporter • Posted: Thursday, December 13, 2018

The sometimes lethal interactions between eagles and wind turbines have given flight to an important technical debate that’s about to press the Fish and Wildlife Service a little harder.

Environmentalists worry officials could understate wind turbine dangers. Some want more data. All recognize the real-world implications of adjusting the academic-sounding “collision risk model,” used to predict the number of eagles that may be killed at new wind facilities.

“The [model] attempts to incorporate existing knowledge of eagle use around a proposed wind facility and the probability of an eagle colliding with an operating turbine,” the American Wind Energy Association noted in an extended public comment period that ends tomorrow.

The wind energy group added that this combination of exposure and fatality probability is used to determine the incidental take permits. These are required under the Bald and Golden Eagle Protection Act to operate facilities that potentially threaten the charismatic raptors (Greenwire, June 20).

“If the Service is underestimating likely fatalities, some facilities will not be required to obtain permits that should have permits, and other facilities could be permitted that fail to adopt effective avoidance and minimization measures,” the Center for Biological Diversity stated.

In a comment accompanied by several hundred pages of research findings and technical analysis, the environmental group’s senior attorney, Lisa T. Belenky, voiced “significant concerns about the validity” of FWS’s latest modeling.

“I have always felt that wind turbines were a great source of harvesting energy, however not enough has been done to prevent migratory bird collisions,” California resident Susan Calcagno wrote. “They cannot see the fan turbines therefore they fly into them and get chopped up.”

The U.S. bald eagle population is pegged at about 143,000. The golden eagle population is estimated to be about 40,000.

Nationwide, there are more than 52,000 utility-scale wind turbines, according to the American Wind Energy Association (Greenwire, Jan. 24).

FWS last updated the risk model in 2016, when it lacked data specific to bald eagles. Since then, the agency reviewed data sets for 419 wind energy facilities and concluded that the exposure to both the golden and bald eagles is lower than previously thought.

The updated collision data are also “slightly lower” for golden eagles, FWS says. For bald eagles, it’s more complicated.

“Where bald eagles are abundant, they engage in social behaviors and intraspecific interactions that may make them more vulnerable than golden eagles to collisions,” the FWS noted. “Thus, the implication that bald eagles are at high risk at a few wind facilities, while their risk is much lower at many others, is tenable.”

The agency is now considering several options. One would “adopt a risk-tolerant policy for bald eagles.” Another “would use higher fatality estimates for bald eagles than for golden eagles,” and a third would seek more information. This last option appeals to many.

“We assert that more information is required to understand variability in exposure and collision probability for Bald Eagles, allowing for better estimation of population impact,” stated the Washington Department of Fish & Wildlife.

The Pacific Flyway Council, an administrative body with representatives from 12 states, likewise declared that “further refined national Bald Eagle [data] … would help to inform the uncertainty in the exposure and collision probability for Bald Eagles.”

A group representing utilities and renewable energy companies, the Energy & Wildlife Action Coalition, called for moving away from the risk model altogether for bald eagles and toward “less complex and time consuming options, such as landscape and/or project specific habitat analysis.”