Governor Andrew Cuomo announced April 27 that state buildings will turn off non-essential outdoor lighting from 11 p.m. to dawn during the times of peak bird migration: from April 15 through May 31 and August 15 through November 15. The governor's office says excessive outdoor lighting can cause "fatal light attraction" among birds who use stars to navigate. The U.S. Department of Agriculture says an estimated 500 million to a billion birds annually in the United States die through collisions with windows, walls, floodlights, or the ground.