The Blue Sky Green Field Wind Farm poses no greater risk to bats than other wind farms in the region, according to a study released last week by the Wisconsin Public Service Commission.
The We Energies wind farm, under construction about 15 miles northeast of the city of Fond du Lac in the town of Marshfield and Calumet, was studied after Department of Natural Resources officials noticed higher than expected bat mortality rates associated with wind farms operating in other states.
The pre-construction study by Western Eco-Systems Technology of Cheyenne, Wyo., was conducted over several months last year to develop “baseline” information about the numbers and types of bats in the area, said Shari Kozlowsky, a DNR conservation biologist.
Forward Energy, which has a wind farm under construction south of Fond du Lac, wasn’t required to conduct a pre-construction bat study, said Kozlowsky.
“Except for one species, bats aren’t an endangered species in Wisconsin and not subject to wildlife protection measures, but their numbers are in decline across the state due to loss of habitat…This study will allow us to compare what those numbers are before and after the project becomes operational,” she said.
The study found plenty of bat activity. Between July and October 2007, bat detectors – devices mounted in several locations either a foot above vegetation or on two 115-foot-tall posts – recorded sounds bats use to navigate in flight. During the 98 nights the study was in effect, the devices detected 33,548 “bat passes” or bat flights that came close enough to the detector to be recorded.
As more passes were detected at the recorders positioned close to ground level than those mounted on the tall posts, Western Eco-Systems concluded the turbines posed a lesser threat for some species of bats than suspected.
The study noted that different bat species fly at different heights and behave differently. Bats that have larger bodies, are poorer at maneuvering and forage away from wooded areas will be more susceptible to fatal collisions with the whirling turbines, according to the study.
The state hasn’t adopted acceptable bat-kill ratios associated with wind farms, said Steve Ugoretz, a DNR environmental analyst. However, it will monitor the impact wind farms have on several species just as it does with other environmental concerns.
To determine actual bat mortality, WEST recommended a follow-up study be conducted after the wind farm becomes operational in June. WEST also recommended wind turbines be located as far from wooded areas as possible, as many bat species frequent these areas to roost and forage.
Kozlowsky said the DNR will review the study, its recommendations and will forward to the PSC any suggestions it feels necessary to protect the bats, although the PSC isn’t obligated to adopt the DNR’s recommendations.
To date, no wind farm in the state has been modified due to conclusions in bird or bat studies. Wind farm construction permits have “re-opener clauses” which allow changes to be made over time as information is developed on how wind farm operations impact wildlife, she said.
We Energies spokesman Brian Manthey said the study shows the wind farm is located where it won’t have an adverse impact on bats.
“This study doesn’t change our initial feeling that we’re in the right area, and confirms what we looked at prior to when construction began,” said Manthey.
About a dozen turbines are currently operating at the Blue Sky Green Field Wind Farm, said Manthey, with no reported bat deaths.
By Kevin Murphy
Special to The Reporter
10 March 2008
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