RIDGEVILLE – From July 25 through Aug. 15 of 2011, NextEra Energy Resources netted 133 bats at 16 sites in southern Jay and northern Randolph counties, where it plans to build a $240 million commercial wind farm.
NextEra conducted the research to determine where 70 to 75 wind turbines could be placed with minimal chances of killing federally endangered Indiana bats.
The Florida-based company’s scientific consultant captured 92 big brown bats, 27 Eastern red bats, eight northern long-eared bats, five Indiana bats and one little brown bat in very fine nets resembling oversized volleyball nets.
“Wind companies don’t want to build multi-million-dollar turbines and have the U.S. Fish and Wildlife Service (USFWS) tell them to turn them off because they’re killing endangered species,” said Tim Carter, an associate professor of biology at Ball State University and an Indiana bat conservation researcher. “So they work closely with the agency.”
At issue is how far away to place the turbines from woodlands, streams and bottomland. Also at issue is the “cut-in speed” of the turbines, meaning the minimum wind speed at which a turbine will begin to rotate and generate electrical power. (The “cut-out speed” is the speed at which a turbine shuts down to prevent damage during high winds).
“There is a lot of debate and discussion about the impact of wind farms on bat communities,” Carter said. “It’s an ever-changing field that is getting better than it used to be. In the preliminary days, turbines killed, frankly, astronomical numbers – hundreds if not thousands a year, each turbine. But they have figured out ways to minimize the effect on these animals.”
The consultant trapped five Indiana bats in nets placed across Goshen Creek where it runs through farm fields edged by a forest; across an access road that runs through a corn field to a woodlot; across an access road surrounded by pasture; and across a county road between two woodlots.
One of the bats, a newly post-lactating adult female, died during processing.
Three of the four remaining bats were radio tagged: two juvenile males and an adult male.
One of the juveniles was tracked to a live shagbark hickory with peeling bark, allowing it to roost between the bark and the trunk. Eighteen other bats were observed at the roost. Because that bat was a juvenile, USFWS treated it as belonging to a maternity colony.
While male Indiana bats roost individually or in small groups, reproductive females form larger groups known as maternity colonies, according to USFWS. The females tend to return to the same summer range annually to bear their young.
The adult male was tracked to a dead sugar maple with peeling bark. The other juvenile was never tracked to a roost but was detected in a woodland between O’Brien Creek and U.S. 27, just north of the Mississinewa River, which is lined with large cottonwoods favored by bats.
Summering Indiana bats mostly roost in trees along creeks and rivers, bottomland and upland forests, according to Carter. In the winter, they hibernate in limestone caves in southern Indiana and other states.
“Wind turbines are placed in the middle of farm fields, which is good for bats, because in the middle of a farm field, there is nothing there for bats,” Carter said.
But wind turbines are a threat during migration.
“Animals at night fly right into them,” Carter said. “Imagine them flying at night 300 to 400 feet off the ground so they don’t bump into a tree. Now wind turbines are in their fly space.”
Which is why USFWS required NextEra to increase the cut-in speed to 7 meters per second, from a half hour before sunset to a half hour after sunrise starting on July 15 and ending on Oct. 1 of each year.
“This means that … we would ensure the wind turbines do not begin operating until the wind speeds have reached 7.0 meters per second, or 15.65 miles per hour,” said Mary Wells, a NextEra spokeswoman. “This can be done by programing the computers to prevent the turbines from starting up at wind speeds lower than that.”
Normally, start-up wind speed is around 11 mph for the turbines NextEra plans to install in Jay and Randolph counties.
Why is cut-in speed important during bird migration?
“If the blades are not spinning as much or as often, it will not impact as many animals,” Carter said.
“For the same reason a non-moving car is less of a threat than a moving car,” Carter said.
From the ground, it doesn’t look like the blades, the size of jumbo jet wings, are moving that fast.
“But they’re spinning at an amazing speed,” Carter said. “The blade tips are moving over 200 miles per hour when they’re spinning. Bats have never had to deal with anything that fast in their landscape. Bats don’t worry about predators, other than owls occasionally. Bats are at the top of the food chain. They’re curious animals. If they see a turbine moving, they want to know what it is. They go take a look, and the next thing you know, they get hammered.”
Sonar doesn’t prevent collisions because it doesn’t travel very far. “They make a very high-pitched noise that attenuates quickly,” Carter said. “They can’t see or hear that far in front of them. Ten to 15 to 20 feet at most.”
‘Permit to kill’
A second condition imposed by USFWS includes placing no turbines within 1,000 feet of any woodland in areas where Indiana bats were captured or roosted during the survey. That is meant to protect resident bats.
Most foraging by Indiana bats occurs within 164 feet of woodland edges, although occasional bats are found in the open, according to NextEra’s consultant.
Conservatively estimating the length of a wind turbine blade at 164 feet would indicate that a turbine placed more than 328 feet from a woodland edge has little chance of harming Indiana bats, the consultant stated in a report filed with the Indiana Utility Regulatory Commission (IURC).
“The 1,000 feet requested by USFWS is three times that size,” the consultant reported.
If that recommendation were followed, wind turbine development could occur across only 9,994 acres of the 23,468 acres to which NextEra has obtained land rights.
“If you do all the things the Fish and Wildlife Service suggests, they will give you an ‘incidental take permit’ to kill up to ‘X’ number of animals per year,” Carter said. “The agency believes it will have minimal impact on the population, but just in case of a freak occurrence, they will not hold you responsible.”
The company intends to obtain a technical assistance letter from USFWS and to apply for an incidental take permit, Anthony Pedroni, director of business development at NextEra, told the IURC.
Because of various “project constraints,” it will be necessary to place 25 turbines closer to wood lots than recommended by USFWS, Wells, the NextEra spokeswoman, told The Star Press. (Seven of those 25 are alternate turbines that may not be built).
“However, in order for the U.S. Fish and Wildife Service to issue a technical assistance letter, the curtailment period (increased cut-in speed) for these turbines will be expanded to include portions of the spring and the entire summer,” she said.
NextEra also secured the services of scientific consultant to perform a bat acoustic monitoring survey spanning seven months in 2011 and 2012 as well as a bird survey in 2011.
Endangered species or species of special concern detected during the survey in the project area included Henslow’s Sparrow, osprey, golden-winged warbler, northern harrier, sharp-shinned hawk, bald eagle and broad-winged hawk.
The proposed wind farm, to be called Bluff Point Wind Energy Center, lies along U.S. 27 northeast of Ridgeville in Randolph County and south of Bluff Point in Jay County.
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