Advocates warn of threats to migrating birds in Chicago

CHICAGO (CBS) -- An advocacy group is sounding the alarm about threats to migrating birds through the Chicago area.

Earlier this month, nearly 1,000 birds died on a single day after crashing into the windows of McCormick Place. Experts said lights and glass windows likely confused the birds, which may have been flying lower to the ground than normal due to rain.

The nonprofit organization Chicago Bird Collision Monitors, which tracks bird migrations, said that overnight nearly 70,000 birds would pass through the Chicago area.

They recommended people who live in high rises turn off their lights and close their curtains or blinds at night.