As wind power gears up in Montana, the effects of large-scale wind projects on wildlife remain a concern: Birds may be in the clear, but bats are running into trouble.

Turbine-related fatalities at Judith Gap Wind Energy Center near Harlowton were 1,206 bats and 406 birds, according to a 2007 preliminary study prepared by TRC Solutions' Laramie, Wyo. office.

Roger Schoumacher, a biologist and consultant for TRC, said the bat fatality count is higher than what generally occurs in the West.

For more than a year, TRC has been preparing the first post-construction avian and bat fatality monitoring and grassland bird displacement surveys-at a cost of more than $200,000-for Judith Gap Energy, LLC, which is owned by Chicago-based Invenergy. The wind farm is the largest in Montana, spanning 14,300 acres of public land in Wheatland County.

Now, Invenergy has decided to go ahead with another year of study, said Judith Gap operations manager John Bacon, to get a "better feel" for the reasons behind the high bat mortality rate.

"The bats were a surprise for us," he said.

Janet Ellis, a wind policy specialist with the Montana Audubon in Helena, said the bats found at Judith Gap were all forest bats from Alberta, Canada, coming through in August and September during fall migration.

"It wasn't expected at all," she said. "But we know so little about bats."

According to Montana Fish, Wildlife and Parks Biologist Allison Begley, many bird groups advocate for better-sited wind farms in order to lessen the impact on wildlife.

"Nobody's opposed to green energy," said Begley, who sits on the technical advisory committee for Judith Gap. "As far as wind energy and bird interactions, it seems that, using some preconstruction surveys, a well-sited wind farm has much fewer impacts on birds."

In the late ‘80s, thousands of dead birds were collected at Altamont Pass and Solano County Wind Resource Areas near Livermore, Calif. The farm's 7,000 turbines make up the largest wind farm in North America, and unfortunately for birds, the most dangerous. The death count sparked cries from the National Audubon Society and U.S. Fish and Wildlife Service and inspired a slew of follow-up studies on large-scale wind developments across the U.S., which has led to better turbine designs-employed at Judith Gap-to mitigate the effects on birds.

Paul Williamson, director of hydrogen and alternative energy research and development at the University of Montana, said the reason for so many bird kills in California had partly to do with siting and turbine construction.

"When the wind turbines were first starting to be put in, California leaders didn't know a couple things. They put some turbines in the flyways," he said. "They didn't know at what height to put wind turbines-some birds fly at one height and others [at] another." And so birds were sliced and diced while attempting to pass through the rotor planes or when landing on top of the towers.

At ten to 20 rpm, the three propellers of the 90-some turbines at Judith Gap rotate slower than the original towers constructed for the California farm, and they do not consist of the lattice construction that can be less bird-friendly.

Bacon said at this point, the bird death count itself is not significant enough to hinder growth at Judith Gap, but if the results of the extended survey indicate an extremely large impact on bats, the cut-in speed of the turbines might have to be set higher.

"Turbines start at 6 mph. There's been some work done where they know when bats are flying through the area, they're flying through in lower winds," he said. "If the winds are higher, they don't fly. So what we could do is change our cut-in speed to 10 mph."

Audubon would like the Montana Department of Environmental Quality to work with stakeholders to ensure new wind projects minimize impacts on wildlife.

"In general, in Montana wind farms are going to have more of a habitat fragmentation," Ellis said. "The bat issue raises some concerns about the impacts of wind turbines on bats in specific areas."

One of the positive things about the Judith Gap wind farm, she added, is that it doesn't have a vast amount of water, which means no shore birds and fewer waterfowl frequenting the area.

"[Wind farms] all kill some birds," Ellis said, "What we're trying to do is figure out a way to make them have the least impact." One way to do this, she said, is by coming up with criteria companies can follow.

"Hopefully the Judith Gap stuff is going to come out, and hopefully it's still going to be a good site," she said. "It's the best site you could find in a place like Montana."