A wave of wind development blowing across Michigan's Thumb may be halted by tundra swans and other wildlife.

DTE Energy has signed up 25,000 acres of farmland for as many as 250 windmills across the Thumb. But plans for up to 43 windmills on 4,300 acres in Lake Township have some residents and bird experts crying fowl - as in waterfowl.

They believe erecting windmills in the township will result in bird kills and injuries, from birds being chopped up or injured by windmill blades.

Lake Township is located along Saginaw Bay, bordered by the Pigeon and Pinnebog rivers and home to the Rush Lake State Game Area, dotted with dunes and trails.

The township is part of a stopover site for tens of thousands of swans and other waterfowl during spring and fall migration, said Caleb Putnam, Important Bird Area coordinator in Grand Rapids for the National Audubon Society.

''Only bad things could happen if you put turbines in these birds' way,'' Putnam said of the swans. ''Specifically, whenever you have a large concentration of birds at one site, they are more susceptible to large losses.''

Putnam said Audubon supports wind power as a way to curb global warming emissions from coal-fired power plants, but siting is important and studies should be done before windmills are put in Lake Township.

DTE officials don't dispute the possibility that the township isn't a good spot for windmills, and say they're working with U.S. Fish and Wildlife officials on setbacks for turbines near the Great Lakes.

For now, DTE officials just want to measure the wind, but township leaders have denied their request to install a meteorological, or met tower.

DTE wants to gather two years of wind data before studying wildlife impacts, said Trevor Lauer, a vice president at DTE.

''If the wind doesn't have the right qualities, then you don't have to worry about the other issues, because you wouldn't put a turbine there anyway,'' Lauer said.

The windmills have divided community leaders, who can see a recently-erected, 32-turbine commercial Harvest Wind Farm to the south, in Chandler and Oliver townships.

Windmills planned by DTE would be 2 megawatts or larger, on 200-foot tall towers with blades as wide as the wingspan of a 747 airliner.

Valerie McCallum, township clerk and Planning Commission member, and Tim Lalley, a member of the Planning Commission and Zoning Board of Appeals, are leading the charge against the big blades.

Last month, the Zoning Board of Appeals denied a variance request from DTE to install a 197-foot-tall met tower in the township, 22-feet higher than permitted by a township ordinance. Lalley and others said the tower didn't meet criteria for granting a variance, and denied the request.

At the meeting, two ZBA members abstained from voting, because they're among the farmers that have signed leases with DTE to put windmills on their land.

One of those members, Zoning Board Chairman Louis Bushey, said he doesn't think the windmills will harm birds - at least not enough to warrant halting the project.

''You've got people that are always negative on something,'' said Bushey, 72. ''It doesn't matter what it is. Some people have trouble with a motor on a rowboat.''

Nationwide, collisions with windmills kill about 2.3 birds of all varieties per turbine, per year, studies show. That could mean about 100 bird deaths a year from 43 windmills in Lake Township.

But birders say those numbers are meaningless because the totals make no distinction between abundant and rare species, and kills can be much higher if a windmill is placed near large congregations of birds.

Lauer said modern-day turbines are designed to be less attractive to birds, and rotate at fewer rpms. He said DTE will likely put up a met tower just outside of Lake Township, then approach local leaders again if the wind data is strong.

McCallum and Lalley say they believe the windmills will not only kill birds, but ruin the township's natural, open landscape.

''I feel we have a beautiful area,'' she said, driving by a bright green field of winter wheat in the township. ''It's unique. I think it's up to us to protect this for future generations.''

McCallum has compiled information from various sources that suggest the township isn't a good spot for windmills.

That includes a 2003 recommendation from the U.S. Fish and Wildlife Service that no turbines be located within 3 miles of a Great Lakes shoreline, within 5 miles of bald eagle nests or between refuges and known feeding areas of migratory water birds and waterfowl.

McCallum said most of Lake Township is within 3 miles of the Saginaw Bay shoreline, and there are eagle nests on the Pigeon and Pinnebog rivers, which border the township.

McCallum and Lalley are among those on the township Planning Commission who are working on a local windmill ordinance, which will govern where windmills can be located in the township - if at all.

So far, both say their research shows the township is not an appropriate site for windmills.

Lalley, 53, said the Harvest windmills built by John Deere Wind Energy should be observed and studied for a couple of years before turbines are erected in Lake Township.

''I think I like the windmills in the proper locations,'' Lalley said. ''I think they're something we need for alternative energy, but I think siting is important.''

Lauer agrees, but said ''the closer we are to the Great Lakes, the better the wind is. At the end of the day, DTE's interest is to develop in the most economical and efficient manner so it costs customers the least amount.''

Putnam said the township borders an Important Bird Area that stretches from Nayanquing Point near Pinconning to Wildfowl Bay, near Caseville.

''It's known to be used by tens of thousands of tundra swans and dabbling ducks, and that's during spring and fall migration,'' Putnam said.

''During the daytime, they will fly many miles inland and sit in large numbers on agricultural fields, in huge flocks.''

Eagles and other raptors also could be harmed by windmills in Lake Township. Those birds like to perch on high places, and windmill towers can put them at risk, Putnam said.

He said bird kills are an issue nationwide, but Lake Township is the first time he's heard from people concerned about windmill development in the Thumb, which also has been proposed in other areas that don't border the bay.

Bushey said he wants to see more renewable energy in Michigan, to reduce the need for coal-fired power.

He said he and other farmers would gain much-needed income from putting windmills on their land, and the township would gain additional tax base. Windmills erected at the Harvest Farm cost about $3 million a piece.

''Don't worry about the geese,'' Bushey said. ''I hunt ducks and geese. If they're standing out in the field and they see you, they're going to fly around you, aren't they? The same thing with the windmills.''

- Newhouse News Service contributed to this report.