Science & Nature
‘Lights Out,’ Chicago. Bird Migration Will Be Intense Thursday Night and Millions Need Safe Passage
(iStock)
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Half a billion birds will be on the move across the U.S. tonight as migration begins to hit its peak, with some 25 million expected to pass over Illinois, putting the entire state on high alert to reduce collision risks.
That means “lights out” for all non-essential outdoor lighting between 11 p.m. and 6 a.m. Shades should be closed, as well.
Van Doren, B. M and Horton, K. G. 2025. BirdCast, migration forecast map. Cornell Lab of Ornithology and Colorado State University. birdcast.info. 09/25/2025)
Already this week, an estimated 9 million birds crossed Cook County on Tuesday night and another 5.4 million flew over Wednesday night as they make their annual journeys south.
(Courtesy of Purdue Aeroecology Lab)
Birds typically take flight after sunset and are often drawn off course by Chicago’s bright lights. An untold number wind up dead after colliding with window glass, with Chicago Bird Collision Monitors reporting hundreds of dead and injured birds on Monday alone, from falcons to hummingbirds.
While a mass casualty incident in fall 2023 at McCormick Place Lakeside Center drew global attention — where nearly 1,000 birds were reported dead from collisions in a single day — bird advocates say the equivalent of that event occurs routinely across Chicago during peak migration.
“This isn’t a new or different or worse problem — it is a continuing problem,” said Annette Prince, director of Chicago Bird Collision Monitors.
Nor is it just a Downtown problem, she added.
“We receive reports and retrieve birds from every neighborhood in Chicago,” Prince said.
McCormick Place has since voluntarily added bird-friendly window film to Lakeside Center, dramatically reducing collisions. Advocates continue to call on City Council to enact a bird-safe building ordinance that would mandate such precautions.
“Of all cities, we in Chicago should see our obligation to provide safe passages for these amazing birds that are critical members of the healthy environment we all rely on,” Prince said.
Contact Patty Wetli: [email protected]
