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Turbine blades pose ‘substantial threat’ to migratory bats — study

The expansion of wind turbines across North America could drive one of the most common migratory bat species to the brink of extinction, according to a new study that calls on regulators and the wind power industry to take immediate steps to address the problem.

The study, published this week in the journal Biological Conservation, investigated whether fatalities at wind power sites “could impact population viability of migratory bats, focusing on the hoary bat, the species most frequently killed by turbines in North America.”

Led by researchers at Austin, Texas-based Bat Conservation International, the paper estimates that if new mitigation measures to prevent bats from colliding with spinning turbine blades are not quickly implemented, “the hoary bat population could decline by as much as 90 percent in the next 50 years.”

The study, which used computer modeling on projected bat populations, included researchers with the University of Calgary, Texas Tech University, the Fish and Wildlife Service, and the Forest Service.

“Our results suggest that wind energy development may pose a substantial threat to migratory bats in North America,” the study says. “If viable populations are to be sustained, conservation measures to reduce mortality from turbine collisions likely need to be initiated soon.”

Winifred Frick, senior director of conservation science for Bat Conservation International and the study’s lead author, said the dire bat mortality forecast in the study doesn’t have to happen and that “effective conservation measures will help not just hoary bats but all bats.”

“We need to implement significant conservation measures to reduce mortality from wind turbine collisions and soon,” Frick said in a statement.

Representatives with the American Wind Energy Association, or AWEA, defended the industry.

It has used radar and worked with FWS on other steps to reduce collisions with passing bats and birds. Those include the use of “ultrasonic sounds that bats can detect to ward them away from turbines,” the early results of which “have shown promise,” Tom Vinson, AWEA’s vice president of federal regulatory affairs, said in an email to E&E News.

He noted that AWEA in 2015 unveiled a best management practice agreement establishing a new voluntary operating protocol that he says is expected to reduce impacts to bats from operating wind turbines by as much as 30 percent.

“And the wind industry is supporting research to improve our understanding of these issues and options to reduce impacts, including the development of technologies to detect and deter bats from wind farms and helping found and continuing to support the Bats and Wind Energy Cooperative and the American Wind Wildlife Institute,” Vinson said.

Wind turbines are not the only major threats to bats, he noted.

A study last year led by the U.S. Geological Survey found that bats hitting large wind turbines, coupled with the spread of incurable white-nose syndrome that has been found in bats in more than half the United States, are the main causes of “mass mortality” in bats since 2000 (Greenwire, Jan. 19, 2016).

“Various bat species have been significantly harmed by white nose syndrome and are at further risk as a result of climate change, for which expanding wind energy is a leading solution,” Vinson said. “The wind industry has a legacy of care for the environment and will continue to work to protect bats while addressing these larger threats to their survival.”

Growing concern

The overall health of migratory bats has been a concern for years.

Bats are an ecologically important species, preying on nocturnal insects that damage agricultural crops and forests, as well as nuisance insects like mosquitoes and flies. They are also important pollinators of numerous plants, including mango and banana trees.

Yet, little is understood about where the highest-risk areas are for bat mortality involving turbines. There’s also a paucity of “basic demographic information about bats in general and migratory bats specifically,” according to the new study.

Frick, an evolutionary biologist by training, called the study results “a wakeup call” to federal regulators, the scientific community, the wind power industry and anyone else who cares about bats.

“Although our modeling focused on hoary bats, the qualitative conclusions are likely broadly informative about the relative risk to other migratory species that share similar life histories and high fatality rates at wind turbines, such as eastern red bats and silver-haired bats in North America, and noctule bats in Europe,” the study says.

So far, the study says, the “only method documented to reduce fatalities at wind turbines is limiting operation during high risk periods, such as nocturnal periods of low wind speeds during autumn migration.”

The study acknowledges that AWEA recently “adopted policies to limit blade movement in low wind speeds as a voluntary operating protocol to reduce fatalities.”

But the study said industrywide adoption of “operational mitigation or emerging technologies,” such as acoustic deterrents, “may be necessary to successfully manage migratory bat populations and ensure stable and viable populations in North America.”

The study also says that a goal of the research is to “inform policy decisions regarding preventing or mitigating impacts of energy infrastructure development on wildlife.”

If the warning is not heeded, the hoary bat “could be the next spotted owl,” said Mike Daulton, executive director of Bat Conservation International.

“Solutions are within our grasp,” Daulton said. “We have great hope that this is a problem that the conservation community, key government agencies and the wind industry can work together to solve.”