According to the Audubon Society, exterior lights left on at night are light pollution to animals like migrating birds. The artificial light disorients the birds and gives them a false horizon when flying at night. Often, birds will fly toward backlit windows in order to correct their flight, ultimately ending in death. At least 100 million birds die every year due to exterior lights. How can you help? Turn off your exterior lights between midnight and dawn, the peak migration hours for birds, and close your blinds and drapes. Use timers if turning lights on and off becomes tiresome.