Wind energy has had an auspicious year in 2024, hitting new milestones in the fight against carbon emissions. For the first time, wind power provided more electricity than coal for two straight months in the United States, and in the European Union, 2024 was the first year in which electricity generation from wind and solar farms overtook that from fossil fuels. Ontario currently has about 2,700 turbines generating 5,500 megawatts of power, which accounted for 9 percent of the province’s electricity production in 2023, and more are on the way. This is all good news — except for the birds, bats and insects whose habitat includes the airspace in which turbines operate.
Of those animals, none are more vulnerable to the impact of wind turbines than bats, the world’s only flying mammals. In particular, turbines affect three widely distributed species of long-distance migratory bats: hoary, eastern red and silver-haired. In 2023, these bats were newly designated as endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). This January, they will also be added to the Species at Risk in Ontario (SARO) list. The new designations are based on research indicating that all three species have suffered population declines well above 50 percent in just their last three generations (six to 18 years). The primary cause of those declines? Death by turbine. Scientists estimate that the three species make up 75 to 80 percent of all bat fatalities at wind turbines in North America.
Now that COSEWIC has deemed these species endangered, the federal government can add them to the list of species at risk under the Species At Risk Act (SARA). At that point, they are entitled to protection on federal lands (the pending SARO listing adds further protection in Ontario). In other endangered-species scenarios, such protection typically means removing threats to the animal’s survival. But the conflict between bats and turbines presents more of a conundrum. “We need solid wind-energy infrastructure in Ontario and elsewhere,” says Christina Davy, associate professor in the department of biology at Carleton University. Although her research on migratory bats helped shape the COSEWIC decision, she warns against a “false fight” between wind energy and bat conservation. “We can run wind energy in bat-friendly ways.”
Navigating this issue is a “delicate balance,” agrees Michael Whitby, director of the Bats & Wind Energy Program at Texas-based Bat Conservation International. He points out that experts believe climate change could produce population declines in 82 percent of bat species in North America. “Wind energy is part of the solution to climate change,” he notes. “But it should not cause biodiversity loss.”
Wind-farm operators insist on another kind of balance. Most bat-friendly measures require wind farms to stop operating at certain times and under certain conditions. Idling the turbines, however, lowers energy production, which reduces profitability, leading operators to argue that any help for bats needs to also assure operators’ economic returns.
For more than a decade, researchers, industry and government regulators have been looking for solutions that meet everyone’s goals. But too many bats are still being killed. Experts attribute this both to operators’ failure to embrace available solutions and the growth in wind-energy generation. Since the latter is not going away, the answer is clear: Ontario and other jurisdictions where these creatures fly must do a better job of implementing bat-friendly practices, technologies and regulations. This must happen quickly to prevent bat populations from falling so low that they will never recover.
At roughly 70 square kilometres, Amherst Island is one of the largest islands in the Great Lakes. Tucked into a bay along the shore of Lake Ontario, 10 kilometres west of Kingston, the island is an internationally recognized Important Bird and Biodiversity Area as well as the site of one of the province’s newer wind farms. The facility’s early years of operation illustrate how wind-farm regulations to minimize bat mortalities currently work in Ontario.
The Amherst Island Wind Project consists of 26 turbines — each with three 55-metre-long blades mounted on 100-metre-high towers — planted over much of the island’s flat pasture landscape. The site began operating midway through 2018 with a potential to produce enough electricity to power 22,500 homes. The following year, from May through October, surveyors from Natural Resource Solutions, an environmental consulting firm the project owner hired, conducted twice-weekly searches under the turbines. They combed the ground to locate and count dead birds and bats, and then used that data to estimate annual mortality rates per turbine.
Provincial rules introduced in 2011 require every new wind farm to do such monitoring for the first three years of operation on a schedule that includes both spring and early fall migrations, when mortality rates typically spike. In the case of bats, the critical figure is 10 dead bats per turbine per year. If, at year’s end, the surveyors calculate that the average number of dead bats exceeds that provincial threshold, the wind farm must start turning off its turbines from dusk to dawn whenever wind speeds at the site are under 5.5 metres per second (m/s). This practice — known either as “operational mitigation” (in Ontario) or “curtailment” (industry-wide) — is based on the understanding that bats fly more when wind speeds are low. The operators must set turbines to turn on (or “cut in”) when wind speeds reach 5.5 m/s rather than the typical 3.0 m/s or 3.5 m/s. “If the turbine stays stationary at low wind speeds — when it wouldn’t be producing much electricity anyway — mortality goes way down,” says Davy.
In the first year at Amherst Island, the average number of bat deaths was 5.4 per turbine, well under the limit. But when surveyors tallied the number of dead bats in 2020, they calculated a mortality rate of slightly more than 10 bats per turbine. At that point, the wind farm was required to start operational mitigation. Death rates fell back under 10 per year and monitoring ended in 2023. However, the operator must now use the higher cut-in speed for the life of the project.
The fact that Ontario has had such regulations since 2011 indicates that the deadly impact of turbines on migratory species has been known for some time. What has taken longer to determine is how many bats are being killed and the effect on their populations.
The reason for that lag is twofold. First, when the number of wind farms was relatively low in the industry’s early years, their accumulated impact was small. Second, migratory bats are remarkably hard to study. Unlike other Ontario bat species that gather in colonies and hibernate together in caves, migratory bats roost in trees, stay hidden by day and lead solitary lives. Scientists know hoary bats migrate to coastal areas of the southern United States and Mexico in winter, but where the eastern red and silver-haired bats go is less clear.
To understand population trends needed for the COSEWIC report, experts had to rely on a range of data sources: acoustic detection rates, rabies submission rates and fatality rates at wind turbines. Davy’s 2021 study, which counted bat carcasses at 594 wind turbines in southern Ontario over a seven-year period, was a critical contribution. She and her colleagues applied a modelling technique that is typically used to estimate population trends in fish and found rapid declines in bat abundance.
The reason for these bat species’ vulnerability to turbines is less of a mystery. They show up in Ontario in the spring, rear their young — hoary and silver-haired bats typically have twins; eastern red bats may have up to four pups — and in late summer and early fall head back south. Spending so much time on the wing puts them at a high risk of running into turbines.
Solutions to reduce that risk could take several forms. As mentioned, once the migratory bats are listed as endangered under SARA they will receive added protection on federal lands. To operate wind turbines there, “permits would be required if there is a risk of killing these or other SARA-listed bats,” says an Environment and Climate Change Canada spokesperson.
In Ontario, existing wind farms operate under a conditional exemption in the provincial Endangered Species Act that requires them to prepare mitigation plans for each affected species at risk and minimize adverse effects. What this means, says Davy, is that every time an endangered bat is found dead at a turbine and the turbine was the clear cause of death, that turbine will immediately have to go into operational mitigation. If construction or operation of a new wind farm affects a species at risk or its habitat, the owner needs a permit with similar conditions.
Smera Sukumar, Ontario Nature’s conservation science and stewardship director, hopes the new listings of bat species create “more of an incentive” for government to work with industry to ensure that the mitigations put in place include turning off turbines during migratory periods. “We’ll just have to cross our fingers and see how that plays out in terms of practicality and protections on the ground,” she says.
More sophisticated approaches to reducing bat deaths also show early promise, says Whitby. Rather than basing mitigation strictly on wind-speed thresholds, some operators and researchers are testing “smart” curtailment methods, such as equipping turbines with acoustic sensors that shut down the turbines when the presence of bats is detected. Other systems model bat activity based on weather patterns. The goal is to more effectively protect bats while reducing turbine downtime. Deterrent devices that broadcast loud, ultrasonic noise to drive bats away are also in the testing stage. Unfortunately, says Davy, “[they] don’t work particularly well,” sometimes even leading to more fatalities.
For now, Davy says the best approach is for all parties to work together to apply the “gold standards” for mitigation: higher cut-in speeds, even shutting down turbines overnight during high-risk periods in the migratory season. “It would slice a tiny piece off the industry’s profits, but it wouldn’t make [the operations] unprofitable,” she says. “I understand why it’s not an ideal option from an industry point of view, but it’s not a win if we’re killing wildlife at the same time as we’re creating renewable energy.”
This article was originally published in Ontario Nature’s ON Nature magazine’s Winter 2024 issue. Top photo courtesy EdWhiteImages/Pixabay. Second image courtesy Pixabay.