Wildlife study shows number of bird, bat deaths caused by wind turbines

BAD AXE — At the midpoint of a wildlife study being conducted for four of DTE Energy’s wind parks in the Thumb, results show 35 bird and eight bat carcasses have been picked up since winter.

“We found a relatively diverse mix of species,” said Rhett Good, senior manager at Western Ecosystems Technology Inc., a Wyoming-based environmental and statistical consulting firm. “We assume all the fatalities are wind-energy related.”

The study, which began in the spring and continues to February next year, attempts to find how many birds and bats are killed as a result of wind turbines.

Huron County’s wind energy ordinance requires developers to submit an avian study to assess potential impacts turbines have on bird and bat species; identify plans for post-construction monitoring or studies; and explain potential impacts and propose a mitigation plan if necessary.

Good is a biologist with 17 years of experience conducting wildlife research, according to the firm’s website. His research in a survey of golden eagles for the U.S. Fish and Wildlife Service was published in the Journal of Wildlife Management. He specializes in threatened and endangered species, raptors, migratory birds and wetlands.

Good said the findings of bird carcasses at DTE’s wind parks in Echo, Sigel, McKinley and Minden Township in Sanilac County thus far are within normal range.

“The takeaways so far are numbers that are probably within what we would expect … and no threatened or endangered species or any of those species of concern have been found so far,” he said. “So far these are all relatively common species for Michigan.”

As for the eight bat carcasses, no threatened or endangered species have been found so far, Good said. He said the number is typical for the spring period and that there will be a lot more information about bats at the next study update.

The study uses 15 search plots spread across four wind parks in the Thumb to ascertain results. Crops must be cleared in the process, and DTE is compensating landowners for losses, Good said.

Good said the firm searches a lot more turbines with roads and gravel paths, even though the surfaces represent a relatively small area where bird and bat carcasses may fall.

“But if it falls on there, there’s a relatively high probability we’ll find it,” he said. “We know we don’t find everything … it’s not a totally even searching surface.”

Still, Good said more than 60 percent of each facility are being searched. That equates to a total of about 70 turbines surveyed across the four parks.

According to the study, all turbines are searched weekly during spring, summer and fall. During winter, the firm searches mostly for larger carcasses.

“Hawks, eagles, swans, we expect those carcasses to last longer so those searches are conducted on a monthly basis,” Good said.

The study also compares DTE’s wind parks in the Thumb to other Midwest facilities, from Minnesota eastward, Good said.

Clark Brock, planning commission chairman, inquired if the fall season would bring different fatality rates, based on migration, weather and activity.

“The first half, basically the spring migration, we haven’t analyzed all the data but what we’ve seen so far is nothing is out of the ordinary,” Good said.

DTE owns 217 turbines in Huron County, with 371 turbines in wind parks spread across Huron, Tuscola, Sanilac, Bay and Saginaw counties.