Up to one billion birds die from building collisions every year in the U.S. In downtown Milwaukee alone — hundreds of birds die from flying into glass buildings each year.
But one local program is working to change that.
Wisconsin Night Guardians for Songbirds, also known as WINGS, has volunteers document bird collisions downtown during spring and fall migration. They bring injured birds they find to the Wisconsin Humane Society’s Wildlife Rehab Center.
All of the data WINGS volunteers gather is used to better understand the scale of collisions and help building managers reduce them.
To learn more about the WINGS program, Lake Effect’s Xcaret Nuñez spoke with Urban Ecology Center’s GIS and Field Data Manager, Amanda Tokuyama, and Research Manager, Maggie Steinhauer, for this month’s Chirp Chat.
You can learn more about volunteering as a WINGS Bird Collision Monitor by visiting the Urban Ecology Center’s website and emailing Steinhauer.
This interview has been edited for length and clarity.
Xcaret Nuñez: How did the idea to create this program start in the first place?
Maggie Steinhauer: The project originated nearly two decades ago with the Wisconsin Humane Society. About three years ago, Urban Ecology joined forces to manage more of the volunteer side of things, the data collection and data analysis, so that the Wisconsin Humane Society could focus on the rehabilitation of birds.
This season we have close to 30 volunteers, comprised of people who are new to birding or seasoned birders. We provide training and materials to make it accessible to folks who are new to birds, or if you're looking to expand your identification skills or get deeper into the birding collision world. We're excited to have seasoned birders as well. So pretty much anyone can volunteer if you have an interest in helping with this project… You don't need to have prior birding experience.
XN: Why is it so common for birds to fly into glass windows?
Amanda Tokuyama: There are two big reasons that birds will collide with glass. One is the glass itself. It’s not easily seen by birds because of how see-through it is. Other times, the glass can reflect habitat back… and they might try to fly into it to land, and they'll hit the window. But one of the big reasons that they might end up around glass buildings, particularly downtown, is because of light at night. It can disorient and confuse birds. When that happens, sometimes they will land and hang out until the sun comes up. But we have the issue of the glass looking see-through; the glass looks like habitat, so they might hit it while they're trying to recover and seek refuge for the day before they migrate again in the evening.
XN: Volunteers go out and monitor the window collisions during spring and fall migration. Why that particular time of year?
AT: Collisions can happen anytime, but migration is when we see a huge volume of birds passing through the area. I think around 900,000 birds crossed Milwaukee County last night. That will continue from [September] through early November pretty much.
Milwaukee and Chicago really are really, really interesting and important when it comes to collision monitoring and research because we lie at the intersection of two major flyways. So we're right along the Mississippi Flyway and the Eastern Flyway; both of those kind of intersect at Lake Michigan, pretty much. So a lot of birds are funneled down along the lake shore, along that Western edge of Lake Michigan through Milwaukee, through Chicago. That's why we get so many [migratory] birds.
General research shows that white-throated sparrows are among the top colliders. It's actually thought it’s because they migrate in groups and use nocturnal flight calls to tell each other where they are, so they often collide in large groups.
But overall, we’ve documented around 3,000 birds having collided with various buildings since we partnered on the project.
XN: What are WINGS volunteers taking notes of when they monitor bird collisions?
AT: Volunteers take note of a couple of different things. One, the most important piece of data that I always request is that they prioritize a very specific location. I basically want to know which pane of glass [a bird] hit. They also collect data the disposition [of the bird]. So whether it's dead when they show up, whether they see just like a smear on the window, where the bird hit and maybe flew away. Or if they had to take it into the Humane Society. They also collect information on species, but that’s an optional field. For people who aren't sure of the bird’s ID, we have them submit photos of the bird. We'll have them take a photo of the back, the belly, and the side of the birds, and so we can go back and identify the birds later or confirm if they're unsure.
XN: What do you do with all of this data?
AT: On a very basic level, we can use this data to show building managers where we recommend that they install mitigation. But at a government level or even an urban policy level, we're informing architects that there are risks to having this much glass. It can also inform government policy — In Madison there’s legislation, as well as in Chicago, where any retrofit above a certain percentage of glass on a building or a new construction is required to have decals pre-installed or fritted glass installed. And just from a broad, conservation perspective, [documenting this data] shows us how big this problem actually is, how pervasive it is and what species are most at risk. We've documented 90 species, which is not nearly as many species that have been documented in general in Milwaukee – it's only about a third – but 42 of those birds are on some kind of regional, international, or statewide conservation plan. So they're at risk, and having this data helps us conserve birds.
Chirp Chat’s Bird of the Month for September 2026
Ovenbird
“It's not the most common one to collide with windows, but it is one of the common ones,” Tokuyma says. “It’s also one of my favorites. Ovenbirds are a type of warbler, so they're pretty small, but unlike a lot of the warblers, they would be considered very plain. But probably my favorite part about them is that they have these stripes on their head that kind of look like a slice of pizza, if you squint your eyes. They have an orange and olive-y colored crown. And they're called oven birds because their nests look like a pizza oven.”
