A wind farm in Montana might be killing more birds and bats than expected, according to preliminary findings of a study by Montana Fish, Wildlife and Parks.

Bats could be mistaking the 25 NorthWestern Energy turbines 35 miles east of Great Falls for trees. But so far, no raptor carcasses have been found, said state researchers.

NorthWestern officials credit work to locate raptor nests before the turbines were installed.

"If we build something we want to build it right," said Sam Milodragovich, a NorthWestern Energy biologist. "We want to know what the risks are and how we can minimize the impacts."

State and utility officials have promised to release bird-mortality data to the public after the two-year study is over. Usually such information is closely held by government and utility officials.

The 40-megawatt wind farm became operational in 2012, the Great Falls Tribune reported.

A preconstruction survey predicted that the wind farm's impact would be low for bats but Fish, Wildlife and Parks estimates turbines killed as many as 397 bats over a year. Those results prompted a second year of monitoring.

Bats produce only one or two offspring a year, said Fish, Wildlife and Parks conservation technician Kim Linnell.

"So knowing reproductive biology, we do believe it's something to be concerned about," Linnell said.

Researchers also found the turbines killed two western meadowlarks over a six-month period.

Great Falls Tribune | http://www.greatfallstribune.com