As dawn broke over the Loop, Annette Prince patrolled the streets armed with a lime green net, racing to collect four colorful birds lying dead under glass skyscrapers before seagulls could snatch them up.
It’s like an Easter egg hunt, she said — just not the fun kind.
Every morning during the spring migration season of March to June, Prince, director of the Chicago Bird Collision Monitors, leads hundreds of volunteers who scour downtown Chicago searching for migratory birds that have collided with windows.
Their busiest period is right now: Mid-May is the peak time for migratory birds to fly north through Chicago. And while millions of birds fly through Chicago this spring, conservationists, architects and city leaders are grappling with how best to protect hundreds of species, as the city serves as both a critical stopover site and a dangerous obstacle along that migration route.
“I came to Chicago because of the beautiful architecture, it’s got one of the most beautiful skylines in the world,” Prince said. “I stayed to help the birds that were being hurt by the skyline.”
Some birds survive window collisions, either stunned or injured, but most die after striking the hard-to-see glass of downtown skyscrapers. The Bird Collision Monitors bring deceased birds to the Field Museum for research and any survivors to the DuPage Wildlife Conservation Center for rehabilitation and release back to the wild.
Between Saturday and Tuesday alone, Prince said her group collected more than 900 birds within a 1.5-square-mile stretch of downtown Chicago, including yellow-bellied Canada warblers and the bright blue indigo bunting. More than 650 of those birds were dead.
“Don’t go to the windows,” Prince told a living warbler perched in a tree at Federal Plaza during a recent morning patrol.
More than 8 million birds representing roughly 250 species travel along the Great Lakes through the bird migration route known as the Mississippi Flyway each year, according to Martin Harper, chief executive officer of BirdLife International, a global conservation network.
Thousands of migratory birds die each year after colliding with the city’s glass towers, and up to a billion across North America, posing a major threat to already declining migratory bird populations worldwide, he said.
Prince estimated that her group recovers up to 10,000 birds annually in the Loop alone. About one-quarter are injured; the rest are dead.
“When we’re looking at 8,000 to 10,000 birds (struck) because the windows aren’t safe, that’s a lot of lives that are needlessly lost, that can’t be replaced,” Prince said. “Most of them are declining species that can’t afford to die because they’ve traveled through Chicago.”
Now, bird advocates across Chicago are pushing for stronger protections, hoping to raise awareness about window collisions and pressure city leaders to follow in the path of other major cities in adopting bird-safe building policies.
An urban journey
During their long migration north, birds such as warblers arrive exhausted and underfed, searching for places to rest and refuel, Harper said.
Chicago’s geography creates a bottleneck for birds traveling along the Mississippi Flyway, as the vast expanse of Lake Michigan to the east and the sparse, open farmlands and prairies to the west leave the lakefront as a primary refuge. This makes Chicago’s parks and shoreline essential resting points for migratory birds.
“It’s like a mecca for birders,” Harper said.
At Montrose Point Bird Sanctuary, Harper joined local bird-watchers at sunrise to observe the migration. He saw everything from Canada warblers to the federally protected piping plovers that nest along Montrose Beach.
Dozens of birders with binoculars lined the sanctuary trails as colorful songbirds moved through the trees. Among them was Miguel “Mikko” Jimenez, a postdoctoral researcher at Lincoln Park Zoo’s Urban Wildlife Institute.
Jimenez studies migratory birds using weather surveillance radar to determine where they stop along their migration routes. In a study published in February, he found birds disproportionately use dense urban areas such as Chicago for stopover habitat.
“The high-level takeaway there is that birds are definitely using cities,” he said. “Whether that’s a result of light pollution drawing them in, or whether it’s the result of urbanizing areas that birds were already using, like coastlines and along rivers and along the Great Lakes, I don’t know. But I know that birds are definitely using cities.”
Earlier that week, Harper accompanied Prince during one of her downtown walks to see firsthand the dangers these birds face.
“The fact that (Chicago) has so many tall glass buildings, that has proved to be particularly problematic for migratory birds,” Harper said.
Prince said migratory birds are especially vulnerable because they are unfamiliar with urban environments, unlike resident native species such as pigeons or sparrows.
“They live here, they’ve learned what buildings are like, they know what glass is,” she said. “But that little (migratory) bird spent his winter down in the rainforest, or natural area with no buildings in it.”
As birds move through unfamiliar cities, she said, they face dangers they cannot adapt to quickly enough.
“A hundred years ago, we didn’t have wall-to-wall glass everywhere,” she said. “They’ve traveled safely to Chicago, had a nice lakefront and had nice green spaces. And now within the last 100 years, we’ve got dangerous obstacles in their way.”
Glass windows confuse birds because they either appear transparent or reflect trees and sky. Birds often perceive reflections as safe habitats and fly directly into them.
Newer building designs can be especially deceptive. Interior trees visible through lobby windows may appear to birds as inviting places to land, Prince said.
During her patrols, she pays close attention to buildings surrounded by landscaping or green plazas, where migratory birds tend to gather.
As she walked through downtown Monday, office workers and maintenance crews frequently stopped her to point out dead or injured birds nearby. Outside 123 North Wacker, a 30-story commercial tower, a maintenance worker directed Prince to a dead Canada warbler and indigo bunting near the building’s glass facade.
“(Chicago) has obviously a vibrant economic scene, but it’s also got a very vibrant birding scene,” Harper said. “So we need to find a way for business and nature to coexist.”
Building a bird-friendly city
The push for bird-friendly architectural standards gained significant traction following a grim milestone in 2023, when nearly 1,000 migratory birds died during a single night of collisions at the McCormick Place Lakeside Center. In response, the facility applied specialized window films the following year, which cut strike-related fatalities by 90%, according to earlier Tribune coverage.
The dramatic reduction in deaths at McCormick Place underscores the high stakes for wildlife along the lakefront, said Gina Parra-Hughes, deputy director of policy and outreach for the City Council’s Committee on Environmental Policy and Energy.
Since then, groups like the Bird Collision Monitors have amplified their demands for a municipal mandate requiring bird-safe glass in new developments and significant building updates.
During a City Council session last July, Parra-Hughes and Committee Chair Ald. Maria Hadden, 49th, listened to testimony from conservationists like Prince regarding the need for legislative action. Parra-Hughes recalled being deeply affected by the revelation that collisions often claim the most healthy birds of migrating populations.
“The best of the best are flying to Chicago and we are killing them,” Parra-Hughes said. “We need to continue being aware that when humans build, that modifies the existence of other animals and ecosystems. I think it’s time to keep that in mind.”
Working alongside Hadden, the lead sponsor of the legislation, Parra-Hughes helped reintroduce the Bird-Friendly Building Design Ordinance, mandating bird-safe materials be used on new constructions, to the City Council this past March. This marks the second attempt to pass the measure after years of delays.
“Making buildings safer for migrating and resident birds will ensure their place in Chicago,” the ordinance’s co-sponsor Ald. Ruth Cruz, 30th, said in a statement to the Tribune. “After all, this is their city, too.”
Prince said Chicago is overdue to adopt standards already implemented in cities such as New York City, San Francisco and Portland, Maine. Nearby suburbs including Evanston and Skokie have already adopted similar bird-safe requirements for new buildings.
For opponents of the ordinance, Prince argued bird-safe design doesn’t need to sacrifice architectural aesthetics.
“Some people may object to it, but if you’re a creative architect, you can do things that are very unapparent,” she said. “A lot of the window films you put on have striping that’s so subtle, if you step back even a little bit, you can’t even see it. It doesn’t affect anything.”
Still, Prince said resistance remains strong among developers and some city officials who worry additional regulations could complicate construction projects and add expense.
“It’s very hard to convince the city,” Prince said. “Developers think it’s going to cost them more or a hassle to have to apply another code to their building. But there are hundreds of building codes, and this one is going to make a difference whether something lives or dies.”
But Parra-Hughes argued the cost burden would be minimal for developers. The working group, which includes the Collision Monitors and the Chicago Bird Alliance, estimates adding bird-friendly glass materials to new construction would cost between 3% and 10% of the total cost of a building project, she said.
The ordinance will also only require bird-friendly glass for the first 100 feet of a building, where most bird collisions occur and “where they spend the most time,” Parra-Hughes added.
The ordinance is currently assigned to the City Council’s Rules Committee.
‘Flyway City’
While lawmakers debate the ordinance, the Chicago Architecture Center plans to spend much of 2026 showcasing the city’s complex relationship with migratory birds and urban design.
On June 11, the center will open an exhibit called “Flyway City: Architecture for a Flourishing Ecosystem” in collaboration with architecture firm Studio Gang. The exhibit will feature examples of bird-safe design and encourage policy changes to make Chicago safer for migratory birds.
“It’s a wonderful opportunity to observe nature in our city and we have a responsibility to better protect birds from colliding with buildings,” lead architect Jeanne Gang said in a statement. “I hope Flyway City inspires a new class of bird-safe design advocates and helps our city advance its legacy of innovative architecture.”
The exhibit will highlight successful examples of bird-friendly architecture, including Studio Gang’s curvy-designed Aqua Tower in downtown Chicago.
Parra-Hughes expressed hope that lawmakers would visit the center’s exhibit to see bird-friendly design implemented in practice while they deliberate on the proposed ordinance.
“This is not just like a city hall issue,” she said. “There are architects, there are designers, there are advocates that are already doing the work.”
Harper said bird-safe architecture ultimately benefits both wildlife and residents.
“People don’t want to be living around buildings with lots of dead birds, and at the same time, people want to have contact with nature and this vibrant birding community,” Harper said.
“Let’s make Chicago safe for all birds,” he added. “Hopefully all those amazing volunteers who tread the streets for hours on end, pick up fewer and fewer birds over the next few years.”
For Prince, the work continues while she waits for the city to act on the ordinance.
“I can’t help them migrate,” Prince said. “(But) I can make sure they have safer passages, and they deserve a better fate than this. Those little birds should have done better.”
As warblers and buntings continue their migration north this spring, Prince and her volunteers will be out in the Loop at 5 a.m. every day, searching sidewalks for fallen migratory birds.
“This is something that’s affecting the global bird population, and yet I can do it right in my own backyard,” Prince said. “We’re in the path of protecting birds that are critically important to the entire planet. It’s right here where we can take action.”
