Wind turbines identified as threat to bats

A group of scientists considering what animals should be added to Canada's endangered species list says wind turbines are a substatial threat to migratory bat species.

This research has direct implications for P.E.I. as it looks to expand its wind energy production, Jordi Segers, national bat health program coordinator with the Canadian Wildlife Health Cooperative told Island Morning host Laura Chapin.

"We've known for a long time that wind turbines are a major threat to bats, especially these migratory bats, but even non-migratory bats," said Segers.

At least two of the bats the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) would like to see listed — the hoary bat and the eastern red bat — have had their calls detected by acoustic monitoring on P.E.I., he said. But it is impossible from those records to estimate population sizes, or even tell if the P.E.I. is a migration route or a destination, said Segers.

The most common way of measuring the threat of wind turbines is to look for dead bats on the ground beneath them, with estimates of 10 carcasses per turbine a year.

But Segers said he believes that underestimates the numbers because scavengers can eat the dead bats.

Not enough is known about bat behaviour to provide a definitive explanation for the threat created by wind turbines, but there are some theories.

Bats, while known for echo-location, also have very good eyesight and migratory bats in particular will use vision for navigation. Bats tend to migrate along shorelines, which is where wind farms tend to be set up. Bats will also use their vision to sight and head for large trees, and they may be mistaking wind turbines for trees.

Switching turbines off during peak migration times seems to be the best solution, said Segers.

"In the spring and in the fall, especially when wind speeds are low and they're not producing all that much power anyway, that seems to be, based on a lot of research, one of the more promising mitigation measures," he said.

Environmental studies around the wind farm at the Wind Energy Institute of Canada at North Cape, P.E.I., have not shown any problems for bats, said institute CEO Scott Harper.

In advance of the wind farm being built a little more than a decade ago, field studies were done that estimated there was a small population of brown bats in the area.

Mortality studies were done during the first three years of the farm's operation, and no dead bats were found, said Harper.

"The mortality monitoring was considered complete after year three and no other concerns or monitoring requirements were raised by the environmental assessment officer," Harper wrote in an email to CBC News.