It’s the not-so-green secret of the nation’s wind-energy boom: Spinning turbines are killing thousands of federally protected birds, including eagles, each year.

Each death is a federal crime. And the Obama administration has prosecuted oil and power companies for such deaths.

But the administration has not prosecuted a single wind farm. An Associated Press investigation has found that it shields the industry from liability instead and helps keep the scope of the deaths secret.

The deaths force the Obama administration to choose between supporting wind energy and enforcing laws that could slow the industry’s growth.

More than 573,000 birds are killed by the wind farms each year, according to an estimate in a scientific journal in March.

The industry says more eagles are killed by cars, poisonings and other causes.