Larger Turbines Pose Peril for Birds

When the U.S. Department of Energy released a report last month championing the construction of larger, more-powerful wind turbines, the wind industry unsurprisingly greeted the news with enthusiasm. With an extension of the “hub height” of turbines to 360 feet, the chief executive of the American Wind Energy Association said, wind energy could expand to all 50 states.

Less ardent was the association’s response to scientists’ well-documented concerns about the half-million birds that die each year from collisions with existing turbines. Some migrating birds, a spokesman said, fly too high to be harmed by rotor blades.

Indeed, some birds do fly very high. But far more travel at the very altitudes that would put them at the greatest risk of colliding with the taller turbines.

The risk is especially high during spring and fall, when migrating birds take to the skies in billions, many traveling vast distances between their wintering and breeding grounds.

A May report from the U.S. Fish and Wildlife Service relied on radar data of fall migration at two locations in Michigan. The greatest density of birds and bats migrating at night occurred from 300 to 500 feet above ground, almost directly at hub height for the new generation of giant turbines.

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