There’s a certain magic to Madison in May. Campus exhales, nature shows off, and for a few weeks, the whole city seems to shift. It’s graduation season, and peak spring migration. And while the spotlight tends to fall on those moving on, it’s also a good time to notice who’s passing through.
Each spring and fall, thousands of birds fly through UW–Madison, tracing migratory paths older than the campus itself. Many of the same places we flock to in spring—Picnic Point, Lake Mendota, the UW Arboretum—also offer food, cover, and rest for birds traveling the Mississippi Flyway, a major avian superhighway.
Some of our most iconic Madison moments happen right where city and nature meet, but that overlap also comes with risk: each year in the U.S., more than a billion birds die after colliding with windows.
“Bird-window collisions are one of the biggest conservation challenges for birds,” said Brenna Marsicek, Director of Outreach for the Southern Wisconsin Bird Alliance (formerly Madison Audubon). “It’s a shockingly enormous number, almost too large to fathom.”
At UW–Madison, collisions are most likely to happen where glass meets green: lakeside residence halls, mirrored facades near trees, and glass that reflects a false sky.
“Birds did not evolve with windows, so [they] have little to no ability to identify them as solid, transparent objects,” said Marsicek. “Instead, they see the reflection of the sky or habitat and fly at it, thinking they’ll land in a shrub or continue flying through clear blue sky.”
Aaron Williams, Campus Planner and Landscape Architect for UW–Madison’s Division of Facilities Planning & Management (FP&M), points out that people and pets don’t instinctively recognize glass either.
“Children often bump into glass when learning their environment,” he said. “Birds, while able to learn cues, unfortunately often do not survive the first collision due to the speed of flight.”
For migrating birds like warblers, thrushes, and flycatchers, that makes urban-natural areas like UW–Madison especially hazardous.
Recognizing this risk, Williams, faculty in the Department of Forest and Wildlife Ecology, and the Southern Wisconsin Bird Alliance began a volunteer monitoring effort in 2018 to track bird-window collisions on campus. That effort grew into the Bird Collision Corps (BCC), a now city-wide citizen science project that tracks where collisions happen during migration and looks for ways to prevent them.
For the volunteers, it’s emotionally challenging work. “It’s really, really sad to pick up a tiny bird that died in such a preventable way,” Marsicek said. “As you pick up the bird, you notice how light it is, what beautiful coloring it has that you hadn’t noticed before, how perfectly designed the feet are.”
Though it’s hard work, the data volunteers collect helps campus planners prioritize where changes are needed most.
One of those locations was Dejope Residence Hall, named in reference to the Ho-Chunk word for the “Four Lakes” that define this region. Set just uphill from the Lakeshore Nature Preserve—part of a designated Important Bird Area—the building offers students a powerful sense of place. But the same windows that bring students closer to the landscape also make the building more dangerous for birds.
To address this, UW–Madison installed bird-safe decals on Dejope’s most hazardous windows last summer. Spaced two inches apart and applied in a subtle grid, the small white dots help birds see the glass as a barrier without disrupting the view from inside.
The impact was immediate: during the fall 2024 migration season, recorded bird strikes at Dejope dropped by 75%.
The retrofit was made possible through the UW–Madison Green Fund, which supports student-led environmental initiatives, in collaboration with faculty from Forest and Wildlife Ecology, students from Audubon Society UW–Madison, BCC volunteers, and staff from University Housing, FP&M, and the Southern Wisconsin Bird Alliance.
UW–Madison first piloted this approach in 2020 at Ogg Residence Hall after BCC data flagged the building as a high-collision site. Following the completion of that Green Fund project, bird strikes decreased by 90%, catching the city’s attention and inspiring action for broader change.
Later that year, the City of Madison passed Wisconsin’s first Bird-Safe Glass Ordinance, requiring all new buildings over 10,000 square feet to incorporate bird-friendly designs. The policy was shaped in part by UW–Madison’s pilot project and moved from concept to adoption in just a few months—an impressively quick timeline for municipal policy.
“I am so proud of the fact that we helped pass Madison’s Bird-Safe Glass Ordinance,” Marsicek said. “These community-level changes go a long way for birds and the people who love them.”
Although the City of Madison ordinance marked a major step forward, it applies only to new construction. In many cases, this takes the form of windows that are permanently etched with a dot pattern before installation. There are no requirements, though, for retrofitting existing buildings that pose a threat to birds.
That gap is where the work continues on campus. Williams has remained a steady presence in this effort, acting as “the glue” between BCC volunteers and campus decision-makers. Each migration season, he helps coordinate surveys, interpret data, and guide conversations about what’s possible.
“The BCC has reinforced the idea that collective collaboration will carry ideas much further than individual pursuits,” Williams said. “The ability for FP&M as a staff unit to collaborate with faculty and community is an incredibly powerful tool.”
Most recently, the team is collaborating with the Green Fund on a new project at the Microbial Sciences Building, where BCC data has shown that the large glass atrium poses a particular risk. This time, however, the team is looking into testing an innovative system trialed by the Cornell School of Ornithology and others that suspends long lengths of vertical cord across windows to increase visibility for birds. They anticipate this approach could be more affordable than the decals and just as effective.
If the pilot is successful, it could lead to more retrofits across campus and, as Marsicek points out, cascading ecological benefits.
“If billions of birds die after hitting windows, the ecological impact of that loss is significant,” she said. “If those birds hit windows, it is likely to kill the bird, which is a loss in and of itself, but also eliminates the potential for that bird to reproduce, eat insects, spread seeds, pollinate, etc.”
For Williams, that kind of impact reflects the broader role a public university can play, not just in supporting students, but in stewarding the spaces it shapes and the communities it serves.
“Personally, this initiative supports what is good about planning and landscape architecture in that a campus is not the way it is because it has to be,” he said. “It is just how far we’ve gotten at making it.”
Your generosity helps student-led sustainability solutions take flight! To support the Microbial Sciences retrofit and other high-impact projects, contact Ian Aley, Green Fund Program Manager, at iraley@wisc.edu or make a gift below.