Three bat species at risk of becoming endangered as wind turbines take heavy toll on wildlife

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Wind turbines – towering emblems of the shift toward renewable energy – have been cited as a primary reason why three of Canada’s native bats species are in existential peril.

The Committee on the Status of Endangered Wildlife in Canada, an independent body that reports to the federal government, recommended on Wednesday that the three species be listed as endangered.

Such a designation would represent the highest level of risk under Canadian law – a fact made all the more striking because it is the first time any of those species have been assessed by the committee.

“There’s lots of indication that all three have been precipitously declining,” said Stephen Petersen, director of conservation and research at Winnipeg’s Assiniboine Park Zoo, who co-chairs the committee’s work on terrestrial mammals.

Among the causes that the committee identified as contributors to the bats’ decreasing numbers, “the mortality at wind farms seems to be the top threat,” he said.

The recommendation for listing the species was issued following the committee’s semi-annual meeting, which concluded last week in Regina.

Included in the recommendation are the hoary bat, the silver-haired bat and the eastern red bat. All are high-flying migratory species that spend their winters in the southern United States or Mexico. The first two range across Canada during the summer, except in the Arctic, while the third mainly occurs in the central and eastern parts of the country.

During their migration, the bats encounter an array of human-made structures along their flight paths, both in the U.S. and Canada, including the swiftly whirling blades of wind turbines.

Studies based on counts of bat carcasses near wind turbines have shown that the toll can be heavy when multiplied across all the units that are currently operating. With each turbine killing on the order of 10 bats per year, the impact works out to tens of thousands of individual animals removed from the population annually in Canada alone.

In 2019, an Ontario government-led study used the trend in bat deaths at wind turbines in that province to demonstrate that populations of all three species, as well as the big brown bat, have declined significantly.

The study, which was part of the supporting evidence for the committee’s recommendation, ruled out the possibility that bats are learning to avoid the structures.

“We’re unintentionally harvesting them out of the air space every year,” said Christina Davy, a conservation scientist who was lead author on the study and who is now based at Carleton University in Ottawa.

The effect is compounded by habitat loss, pesticides in the food chain and other threats that bats must cope with.

“The good news is that we have tools to reduce the mortality from wind turbines,” Dr. Davy added. “They’re not ones the industry loves, but they work.”

Those tools include shutting turbines down during periods of low wind when bats are likely to be flying but the energy return is low, as well as during the peak of the fall migration season.

Brandy Giannetta, vice-president of the Canadian Renewable Energy Association, said the domestic wind industry is aware of the issue and has been taking steps to reduce the impact on bat populations.

“We are not surprised by the recommendation for listing,” she said.

Fungus that causes white-nose syndrome in bats is found in B.C.

She added that turbine operators, using sound-based devices, can also detect when bats are near and, in some cases, can emit sounds that are intended to ward bats away.

But others say the measures deployed to date are not sufficient, as is made apparent by the three species now recommended for listing.

The toll of wind turbines on bats is “one of the best-kept secrets – in a bad way,” said Cori Lausen, director of bat conservation with Wildlife Conservation Society Canada.

WCSC and other groups have been warning of the danger posed to bats by wind turbines for years, but the warnings seemed to have little impact, she said.

Because bats can live for decades and tend to have only one pup per year, high losses because of wind turbines have an enduring effect that is difficult to reverse.

“They have no way to bounce back from that kind of mortality rate,” Dr. Lausen said.

The measured pace of Canada’s species law means that the committee’s recommendation will not be formally submitted until later this year. If Ottawa agrees with the recommendation and lists the three species as endangered, the designation will apply only on federal land. Such an outcome is unlikely to have a meaningful impact on bats unless it is supported by provincial regulators who oversee the wind industry.

“The provinces need to step up and recognize that these three species have a very dire outlook if something isn’t done soon,” Dr. Lausen said.

Dr. Petersen said that the committee’s recommendation can serve as a wake-up call that draws more attention to the issue.

“I’m hoping that even though this is not great news, it’ll spur some action,” he said.