Utility-scale wind-powered electrical generation facilities are rapidly expanding in Illinois, with feasibility studies underway for installations in no fewer than 37 of the State's 102 counties; construction completed for approximately 300 MW of capacity; and construction for an additional 900 MW or more pending in the next two years. The wind-generation industry estimates Illinois can provide up to 9,000 MW from up to 6,000 turbines.
Adequate scientific data does not yet exist to affirm or refute the potential biological significance of mortality directly caused by utility-scale wind turbines. While birds are killed through collisions with wind turbines, it is rare that such losses may be significant to particular species. Bats may be in greater jeopardy from wind turbines because two to three times as many bats are killed. Losses of both animals are higher during migration periods.
Only one mortality study has been performed at an Illinois wind energy installation. In that case, it is estimated that only one bird per turbine is killed per year. While other avian species were killed, only one raptor (a red-tailed hawk) was killed. However, three times as many bats were killed through collisions. No remains of threatened or endangered avian or mammal species were found. It remains unclear how significant this level of attrition may be.
While public attention centers on the apparent threat to birds from collisions with wind turbines, collision mortality is only one of many potential adverse effects to wildlife posed by wind energy installations. Habitat displacement and fragmentation are of potentially greater significance to a wide array of wildlife, including mammals, reptiles, amphibians, fish, and invertebrates. Similarly, natural areas could be adversely affected by erosion, sedimentation, water quality degradation, and shadowing associated with wind turbine construction and operation.
One area of concern for Illinois is Lake LaSalle, a cooling lake for a nuclear reactor that is located in an area that has high potential for wind projects. The lake has become an important wintering area for migratory waterfowl because the lake rarely freezes, and surrounding lands provide sufficient food resources if snow cover is not too deep. Impacts to foraging birds could prove significant if a wind project is sited in the area. Although no turbines have been suggested for the Lake Michigan area, this could be another location of concern because it is a known flyway for birds and bats.
To better understand the impact of wind farms on Illinois birds, the state could:
- Develop a map of areas of concern to highlight protected natural resources and wildlife areas where developers should take extra precautions when developing wind farms,
- Fund a major study of bird abundance and richness before and after turbines are constructed at representative sites in the state, and
- Fund a comprehensive study of bat mortality around existing wind farms.
Until the impacts are better understood, regulatory action for wildlife protection is not recommended.