Advocates and volunteers say over 1,000 birds were killed or injured after colliding with buildings in the Chicago area during fall migration this past weekend.
Most birds were rescued or recovered in and around downtown Chicago and on Northwestern University’s Evanston campus Saturday and Sunday, according to Chicago Bird Collision Monitors.
Volunteers were anticipating that north winds on Friday night would encourage many migratory songbirds to fly south that evening so as to not overexert themselves as they burn up large amounts of energy while they travel hundreds of miles.
The DuPage Wildlife Conservation Center received 274 birds on Saturday alone from building collisions in downtown Chicago, and 60 more Sunday, according to a spokesperson from the county’s Forest Preserve District. Their new patients represented over 20 bird species, including 80 golden-crowned kinglets and 73 brown creepers.
“Birds were falling every five seconds,” said Jennifer Bell, a volunteer with the collision monitors, who was out checking downtown sidewalks for birds between sunrise and 1 p.m. on Saturday, and later in Fulton Market. She picked up 22 live but injured birds and 40 dead ones.
Advocates say the devastating toll highlights the urgent need for “effective, preventive measures,” specifically a Bird-Friendly Building Design Ordinance to establish protections for qualifying new buildings in Chicago. Besides policy-level action, they say design choices and reduction of light pollution in existing buildings can address preventable collisions.
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Allison Sloan, a volunteer with Bird-Friendly Evanston, bags 42 live, injured birds as dead birds lie on the pavement on Northwestern University’s Evanston campus Oct. 17, 2026. Building collisions killed or wounded over 1,000 birds in downtown Chicago and Evanston. The injured birds were taken to DuPage Wildlife Conservation Center for examination and treatment. (Holly Greenberg)
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Allison Sloan, a volunteer with Bird-Friendly Evanston, bags 42 live, injured birds as dead birds lie on the pavement on Northwestern University’s Evanston campus Oct. 17, 2026. Building collisions killed or wounded over 1,000 birds in downtown Chicago and Evanston. The injured birds were taken to DuPage Wildlife Conservation Center for examination and treatment. (Holly Greenberg)
Chicago, which sits along a major migratory route — the Mississippi Flyway — is the most dangerous U.S. city for millions of birds migrating in the spring and fall, according to Cornell University’s renowned Lab of Ornithology. According to the lab’s BirdCast, over 5 million birds crossed Cook County on Friday night.
“We are such an important place on migratory routes that they’ve evolved to travel on for decades, tens of thousands of years, even before there was a city here,” said Annette Prince, director of the collision monitors. “Birds use this as a place for safe passage, and we want to make sure that Chicago has beautiful architecture, beautiful buildings, but also can keep the beautiful birds that we’re really privileged to host.”
Experts estimate that a billion birds die crashing into windows in the United States every year. For context, BirdCast estimates that about a billion birds were in flight over the contiguous states Friday night.
Another such night in the country also led to a similarly deadly mass collision in Chicago three years ago when, in early October 2023, 960 birds died at McCormick Place Lakeside Center. Experts say it marked the most bird collision deaths ever recorded in the country in a single event.
“It felt like that. It had that feel to it, on Saturday,” Bell said.
So far this fall migration, she has rescued 350 birds through her involvement with the collision monitors. “And that’s just me,” she said.
“This time it wasn’t, like, at one location, like one place, but everywhere,” Prince said. “We were getting a call every 30 seconds on our hotline. We must have gotten — I can’t imagine how many calls we got. We must have gotten at least 200 calls that day. Birds everywhere.”
That’s the issue, she said: The problem is not limited to a downtown area or to tall buildings. Rather, birds collide with glass of any kind, particularly in the first 100 feet above the ground.
“And that gradual accumulation can get you 1,000, as we found downtown,” she said. “If you extrapolate that to the entire 230 square miles of Chicago — and we looked in just 2 square miles — those numbers can multiply into the tens of thousands of groups that must have gotten hurt over the weekend.”
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Glass buildings are particularly deadly to birds, advocates say, as the reflections of trees and the sky — or transparent glass that is essentially invisible — can trick them into thinking it’s safe. Birds often strike glass flying as fast as 30 mph, suffering fatal brain trauma or devastating injuries. In cities, they can also become disoriented at night by artificial lights.
At the Northwestern campus Saturday, volunteers rescued over 40 live, injured birds, including 35 by the Kellogg School of Management Global Hub, said Allison Sloan, a volunteer with Bird-Friendly Evanston. The building has a curved glass exterior to echo the rolling shoreline, according to the school’s website, “while the glass mirrors the water and sky in every direction.”
In a statement Tuesday, a spokesperson said the university is committed to being a good neighbor and community partner.
“This includes implementing active and passive strategies to reduce bird collisions on campus, an issue we have been working on for the past decade,” the statement read. “Despite these efforts, there regrettably was an increase in bird strikes at some of our buildings over the weekend, which we believe was due to a windstorm. We continue to monitor the situation.”
Bird-friendly measures on campus have included installing window film on existing glass in parts of the Kellogg Global Hub and other lakefront buildings. The Ann McIlrath Drake Executive Center is under construction and set to open in 2027, and will have a glass façade. The spokesperson said it will have ceramic frit, a pattern baked into the glass during manufacturing. In 2022, Evanston adopted a bird-friendly building design ordinance.
The university has also established guidelines for buildings that have had bird collisions during migration periods to turn off lights and lower shades.
“A steady drip of birds being killed at lots of buildings is what causes the problem,” said Doug Stotz, who recently retired from his role as senior conservation ecologist at the Field Museum. “The big nights are particularly unfortunate because … these birds are getting a chance finally to move because the weather is right, and then they run into a building and die. It just feels so cruel.”
In March, Ald. Maria Hadden, 49th, introduced an ordinance to amend the city’s building code and require bird-friendly design on non-residential and high-rise buildings. It was sponsored by Brian Hopkins, 2nd, and Ruth Cruz, 30th, and co-sponsored by 18 other City Council members.
“Another migration season has passed without any standards in place to prevent unnecessary bird deaths,” Hadden said in an emailed statement to the Tribune. “It’s time for the development community to do the right thing for Chicago and our environment and support the Bird-Friendly Design ordinance so we can catch up with other major cities, including New York and San Francisco.”
The proposed ordinance moved this summer from the rules committee to the zoning committee led by Ald. Gilbert Villegas, 36th, whose office said discussions regarding language remain ongoing.
“It’s just been sitting for a long time,” said Robyn Detterline, the advocacy chair of the Chicago Ornithological Society, which she represents in Bird Friendly Chicago, an alliance of four local groups, including the collision monitors, the ornithological society, the Chicago Bird Alliance and the Feminist Bird Club’s Chicago chapter.
Bird Friendly Chicago is supported by the broader Chicago Collisions Coalition, made up of over 40 local, state and regional organizations.
Prince said bird-friendly buildings can be the difference between life and death for living creatures, “the way any safety feature on a building would do,” such as a smoke detector or a sprinkler system.
“These are unnecessary deaths,” she said. “That’s what makes it even more heartbreaking: That we know what to do, but we still aren’t implementing it.”
Opponents of the ordinance have claimed it would stall development and increase the cost of construction. But proponents say including bird-friendly glass from the beginning can increase a large development’s total budget by less than 1%.
“If you do it from the start, it can add almost no additional cost,” Prince said. “It can be a minimal design material investment.”
Some design measures to prevent bird collisions include patterned glass, exterior screens or other visible treatments that can help birds recognize windows as a barrier.
The windows at McCormick Place Lakeside Center encompass an area of 120,000 square feet. After the 2023 carnage, the Metropolitan Pier and Exposition Authority (which owns and operates the center) applied visible markers — a film of tiny dots — to the glass, reducing bird collisions by 95%, according to an analysis by the Field Museum.
For decades, the convention building caused about 1,000 deadly collisions per year. Since the film was applied, the deaths reportedly plummeted to 18 in the fall of 2024.
But this weekend, Stotz said, showed “that fixing McCormick Place hasn’t fixed the problem.”
“And I think this is just another indication (that) we really need the ordinance,” he said.
Beginning in October 2023, the convention center also reportedly implemented additional new bird-safe measures, including closing drapes and blinds overnight and turning off non-essential exterior lights.
The city of Chicago, alongside the Chicago Bird Alliance, the Chicago Bird Collision Monitors and the Building Owners and Managers Association, has since 1995 encouraged buildings — either tall or located alongside the Chicago River and Lake Michigan — to participate in the Lights Out Chicago program and turn off or dim decorative and non-essential lighting every night in the spring and fall, from 11 p.m. until sunrise.
“When I come into the city in the dark on Saturday morning, every major building with major lighting has its lights either extinguished or dimmed,” Prince said. “We imagine that many, many birds were saved by the fact that they weren’t drawn in by the bright lighting that a lot of cities have. Chicago has been a success in that.”
She hopes the city can replicate that success again and that, by requiring bird-friendly features in new buildings and major renovations, the move will lead the way for existing buildings to retrofit on their own.
“The sooner we do this, the better,” Prince said. “We can’t afford to wait longer and have more and more unprotected buildings going up, because we will have to live with the consequences for decades to come. So it cannot happen soon enough.”