Wind power is key to efforts to produce clean, limitless energy and to slow global warming. It's one of the world's fastest-growing energy industries. But there is mounting evidence that expanding "wind farms" are taking a toll on airborne wildlife. Thousands of birds and bats are killed every year by collisions with the the wind towers and their giant blades. As VOA's Zulima Palacio reports, environmental activists are taking the wind energy industry to court to find a solution.