In many cities around the United States, building owners have voluntarily agreed to extinguish their exterior decorative lighting and to dim atrium and lobby lights at key times during the migration season.
Landbirds such as warblers, thrushes, and kinglets migrate at night and can be drawn off course by tall lighted structures in their flight path. Scientists aren’t sure why this happens but it may be related to the fact that among many navigational cues, birds use the stars to stay on course. Lighted skyscrapers may simply confuse them. Birds circle builings and become exhausted. They are then more vulnerable to collisions with windows and other structres, and are easy prey for predators such as the gulls who have learned to patrol urban streets in the early morning hours.
Toronto, Chicago, New York, Minneapolis-St, Paul and Detroit have some of the most successful programs. This action has the potential to dramatically reduce the number of bird fatalities caused by city lights. In addition it will save money and electricity while reducing carbon emissions.