Rfalconcam Forum

Cities help migratory birds by turning off building lights

October 19, 2009, 9:45AM

You've experienced a form of it yourself while driving at night: oncoming headlights make it hard to see. It turns out migratory birds flying at night can be disoriented by building lights and sometimes fly into them.

The American Bird Conservancy reports that numerous states and cities are asking businesses and government agencies to dim or turn off building lights during the spring and fall migratory seasons.

Chicago started the first voluntary "Lights Out" project in the United States, spurred by increasing bird mortality caused by the growing number of tall buildings. Now, all tall buildings in the downtown area dim lights for five months each year, saving an estimated 10,000 birds annually, as well as significant amounts of electricity.

"Many people didn't understand why the birds were dying. Once they learned it was due to the lights, they were happy to help," said Linda Day Harrison, a member of the Building Owners and Managers Association of Chicago.

In 2006, Detroit Audubon's Project Safe Passage inspired Michigan Gov. Jennifer Granholm to proclaim spring and fall migration periods as Safe Passage Great Lakes Days. The San Francisco Board of Supervisors is considering an ordinance requiring all commercial buildings to turn off lights after 9 p.m., or one hour after the close of regular business. "Lights Out" programs now exist in  Toronto, Houston, Minneapolis-St. Paul, Indianapolis, and Boston.

Many bird species migrate at night, orienting to stars and the Earth's magnetic field. Artificial lights can confuse them, particularly on overcast nights when stars are not visible and birds fly low. Birds in large numbers will circle buildings, towers, and other lighted structures until they collide or drop from exhaustion.