The Texas Hill Country, home to the world's largest remaining bat colonies, has recently been the focus of proposals for wind energy projects. We are deeply concerned about the potentially serious consequences to Hill Country wildlife — ironically, from an energy source commonly labeled "green."

Several of America's leading wind energy producers — Florida Power and Light, PPM Energy and AES SeaWest — have investigated the feasibility of large-scale wind energy facilities in the Hill Country, and we applaud them for their decision to avoid that area because of exceptionally high risks to wildlife.

Half a dozen caves and several bridges and tunnels harbor huge maternity colonies of Mexican free-tailed bats, with a total combined population estimated at close to 100 million. These bats consume about 1,000 tons of insects nightly, specializing on the state's most costly crop pests, including corn earworm, armyworm and tobacco budworm moths. By consuming billions of pests before they can descend on crops, Mexican free-tailed bats perform vital services that, if lost, could be extremely costly.

Clearly, these bats are invaluable to Texas agriculture, not to mention tourism. Austin's Ann Richards Congress Avenue Bridge colony generates about $10 million in tourism annually. Unfortunately, recent reports from Oklahoma suggest that Mexican free-tailed bats, especially pregnant and nursing mothers, are among America's most vulnerable species when it comes to being killed by wind turbines.

Other sensitive areas on the Texas Gulf Coast also are of deep concern. The Gulf Coast is an area of primary importance for migrating wildlife. The area serves as a continental funnel for the most populous and diverse array of migrating songbirds, shorebirds, raptors and others, including virtually the entire populations of many species. Many birds that breed east of the Rocky Mountains and the Canadian Arctic pass through this area, the most ecologically diverse region north of the tropics.

Though Texas leads the nation in installed wind power producing capacity, including about 1,400 turbines, no peer-reviewed monitoring studies of wildlife impacts have been mandated by the state or conducted at existing facilities. External scientific studies on impacts of wind energy development in Texas are desperately needed. Those from other states suggest problems for bats that, if not remedied, could threaten entire species. Habitat-related effects from wind energy development are largely unknown but could prove to be serious if facilities are sited inappropriately.

Though it is a private landowner's decision whether to participate in wind energy development, overarching concerns for effects on wildlife create a need for caution. Development of wind energy in areas of high wildlife usage, such as certain areas within the Hill Country and Gulf Coast, should be avoided until credible scientific documentation of threat levels and solutions has been gathered.

We applaud AES SeaWest's recent conclusion in a letter to Gillespie County community leaders dated Aug. 8:

"We have learned that there are several sensitive species and their habitats that are known to occur in the area, and that these sensitive species and bat colonies could be incompatible with large-scale wind energy. As a company that places an emphasis on environmental stewardship and preservation of wildlife, we are concerned that the site may not be suitable from a wildlife standpoint, and is therefore not a good use of our development resources."

The environmental consciousness demonstrated by AES SeaWest in the Hill Country must be emulated throughout the wind-energy industry. Companies that put wildlife at risk cannot claim to produce "green energy."

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Merlin D. Tuttle, Ph.D., is president of Bat Conservation International. Thomas H. Kunz, Ph.D., is a professor and director of the Center for Ecology and Conservation Biology at Boston University.