In recent years, bird and bat mortality caused by wind turbines has been in the news. At the April 13 City Council meeting that approved a Request for Information regarding Evanston’s proposed wind farm nine miles from shore, the issue of how such a wind farm would affect birds was brought up.

We write to encourage that science-based research determine how the turbines will affect birds.

We’d like to lay out some facts:

Most people in the national bird conservation community support wind turbines that are sited appropriately. Our reliance on oil poses serious risks to birds and other wildlife – the current oil spill being but one example on a very long list.

Appropriately sited turbines kill few birds. The figures in the box show that bird mortality rates from existing wind farms (which, with very few exceptions, are not sited in migratory flyways) pale in comparison to other anthropogenic sources.

Government and conservation organizations caution against siting wind turbines in migratory flyways. Results elsewhere in the country have shown unacceptable levels of bird mortality.

Lake Michigan is an enormous migratory flyway. The Illinois portion of Lake Michigan has just been named an Audubon Important Bird Area because of the numbers of migrating and wintering waterfowl. Seven million migratory birds have been estimated to pass through Chicago, and most of them also pass through Evanston and its lakefront.

We do believe it is possible for wind power and migration to co-exist. However, due to the special nature of the threat to migratory birds, a site cannot be selected without very careful study of the ramifications. We are setting precedents in the Great Lakes region. Fortunately, offshore wind turbine regulations are stiffer than for land-based wind farms, and call for a study of environmental impacts. We hope that regulating agencies as well as the City of Evanston will use this opportunity to understand and define which locations in our vast migratory flyway would result in minimum bird mortality. (All involved should recognize that birds will be killed by these wind turbines.)

Often when we think of wind power and birds, we think of collisions. The threat of collision from these turbines needs to be carefully studied. Landbirds of the type that are showing up in your yard now – the warblers, orioles, thrushes and their colorful kin – migrate in a vast blanket over the region, and those flying over the lake head for shore as dawn approaches. On days of poor weather and lowering cloud cover, they are forced to fly at altitudes that would bring them into contact with turbine blades. Questions about how much mortality would be expected from collisions and whether turbines could be stopped in adverse weather conditions need to be answered.

Just as important is the study of the effect of habitat disruption. Lake Michigan’s offshore waters provide habitat for hundreds of thousands of migrating waterfowl, some of which spend the entire winter living on the lake. Yet we know very little about which specific areas they use, except for those visible from shore (such as the spot off the Lighthouse Beach that always hosts a mixed flock of ducks throughout the winter). We also don’t know much about how they use these areas and the particular characteristics that draw the waterfowl to them. We must know much more before we begin building structures in this winter habitat. This is especially critical because studies of wind turbines in the North Sea show that loss of habitat is a bigger threat to waterbirds there than collisions.

At the City Council meeting on April 13, Libby Hill testified that research on effects on bird habitat as well as migration must be included in the environmental concerns and said she did not favor the proposed wind farm, but supported research on the subject. There is a wide gulf between favoring research and favoring a project. To illustrate how controversial the project is beyond Evanston’s borders, on April 15, 2010, the Chicago Audubon Society, a local Audubon chapter affiliated with the National Audubon Society, voted unanimously to oppose wind turbines in the lake. The support of the birding community for the proposed wind farm depends on three things: location, location, location. It will require two to three years of careful research to assure that a particular location is not likely to cause unacceptable levels of bird mortality.