Some say counting carcasses isn't enough.

That's why Illinois is changing the way it wants studies of wildlife around wind farms to be performed as more of the clean energy installations are planned around the state.

Previous research has been based almost entirely on mortality counts, the process by which bird and bat carcasses are scooped up early in the morning within a several hundred foot radius of wind turbine bases.

But studies now are aiming to determine a more long-range impact on avian and terrestrial creatures by examining how animals react to the sudden presence of a vertical structure soaring as high as 450 feet into the sky.

The shift in practice comes as other mortality studies are under way in the area, but only a few have been completed in the state. One investigation of 33 turbines at the Crescent Ridge project in Bureau County found an insignificant number of kills, results similar to most other studies performed around the country.

But data provided by such studies is limited in its applications, according to a state agency that relies on the reports to gauge the effects on wildlife. And the Illinois Department of Natural Resources is working to coordinate more comprehensive environmental examinations of wind projects currently in various stages of development.

"It's unfair to assume, I think, that there's no environmental effects from wind (energy)," said Keith Shank, an impact assessment specialist with the DNR. "Until we get some firm data, the problem is, people are making multimillion-dollar investments with insufficient information."

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Illinois has declared that it wants 25 percent of its energy supplied by renewable sources by 2025 - and 75 percent of that portion generated by wind - prompting one developer to claim Illinois is the next Texas, the state with the most existing wind energy capacity.

Wind farms in Illinois currently produce 390 megawatts of electricity, with another 420 megawatts currently under construction. According to the American Wind Energy Association, Illinois has the potential to produce 6,980 megawatts total, and more than 80 developers have registered to connect turbines and generators to the power grid.

Developers ultimately receive the green light for a project from individual counties, which issue special-use permits. The county zoning committees that deliberate on the permits are required to consult with the DNR about any possible environmental impact from the turbines.

"If we don't have any threatened or endangered species in the area, or a natural protected area, then the consultation is effectively over at that point," Shank said.

The agency can, however, recommend whether certain aspects of the project should be modified or studies should be conducted. But the counties have sole discretion over whether the DNR's suggestions are required of developers.

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In the case of the Crescent Ridge wind project near Tiskilwa, Bureau County asked for a mortality study, with a special concern on migrating waterfowl that pass through the Illinois River corridor on annual journeys north in the spring and south in the fall.

Performed by Curry & Kerlinger LLC, researchers looked for dead birds and bats around each of the 394-foot-tall turbines between September 2005 and August 2006, finding a total of 10 bird and 21 bat fatalities. No two of the same species of bird were killed. Most were songbirds, but one red-tailed hawk died.

The researchers extrapolated that 31 birds and 93 bats died near turbines during the study period. The average suburban house - or, more precisely, its windows - kills four times more birds per year than the individual turbines at Crescent Ridge.

"Overall, it appears that the mortality of birds and bats at the Crescent Ridge site is small and not likely to be biologically significant," the report concluded when it was issued in May 2007.

The report also noted, however, that only six of 112 wind projects in the Midwest had been studied at that time - and only three of those were major wind farm installations.

And although Shank agrees with its methodology and "biologically insignificant" conclusion, he says the study wasn't designed to address more consequential questions.

"The study was fairly limited," he said. "The effects (of turbines on wildlife) are going to be indirect. . . . You could have birds that are going to be weak, half-starved or more susceptible to disease" because they avoid flying near turbines to habitat that is critical to their survival.

That's why the DNR and U.S. Fish and Wildlife Service are now suggesting so-called habitat-use or displacement studies to counties considering special-use permits for wind farms.

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Rather than cataloging what turbines kill, those studies would survey wildlife populations over a certain period before turbines are erected and compare those findings to an animal census after construction. The findings could ultimately ascertain whether specific species react negatively to the massive towers.

The early phases of some of those studies will begin this spring. Western Ecosystems Technology (WEST) Inc., a consulting firm based in Cheyenne, Wyo., that has performed wildlife studies related to wind farms for a dozen years, will survey American golden plover populations in the eastern part of the state as the shorebirds migrate north through areas where wind turbines are destined.

"We would look at where the turbines are going and everything within a mile of them," said Greg Johnson, a senior project manager with WEST, which also is currently working on two phases of mortality studies for the Twin Groves wind farm in McLean County.

Shank thinks the more evolved studies should shed more light on any environmental impact of such a green energy source and help the state shape the way it deals with what is expected to be the influx of new wind farm construction over the next several years.

"We may find in a few cases that the effect on habitat use might be more significant," Shank said.

Matt Buedel can be reached at 686-3154 or mbuedel@pjstar.com.