Annually, two significant migration cycles occur, where birds, insects, fish, and many mammals travel north in spring for nesting and breeding, then head south in winter to feed and rear their offspring. Utilizing BirdCast, a seasonally active tool providing bird migration “heat maps” across the U.S., ornithologists observed an unprecedented migration of one billion birds on a single night in October 2023. The previous year saw 1.2 billion birds migrating. However, on the night between October 4 and 5, nearly 1,000 birds perished in Chicago after colliding with a single building.
The McCormick Place Lakeside Center, located along Lake Michigan’s shoreline, stands isolated in a park-like setting and features windows spanning the equivalent of two football fields. Birds flying along the shore often mistake the glass reflections of nature for reality. On the morning of October 5, hundreds of birds tragically succumbed to this architectural illusion.
Artist and educator Holly Greenberg was shocked by this news. Although familiar with nature and passionate about sustainability, she was unaware of the extent of bird collisions in the U.S. While on sabbatical from Syracuse University, Greenberg joined a group removing invasive buckthorn at a Chicagoland arboretum to make room for native trees. A fellow volunteer lamented the irony of creating new bird habitats while birds mistakenly fly into reflective glass.
“That was the first time that I’d heard that these birds were crashing into windows in Chicago,” Greenberg recalls. After reading about the massive collision at McCormick Place, she thought, “Oh man, something needs to be done.” This realization led to the creation of the multi-year project Bird Collisions in the Anthropocene.
In 2024, Greenberg launched the initiative to raise awareness and educate people on preventing such incidents. With data from the Chicago Field Museum and the assistance of lead ornithologist Dave Willard, Greenberg identified that 10,863 birds were found dead after striking Chicago buildings in 2023.
Annually, an estimated one billion birds die from window collisions across North America. The Chicago Bird Collision Monitors (CBCM) program works to gather this data while striving to protect, rescue, and advocate for birds. Volunteers walk the city’s streets every morning to collect fallen birds, aiming to rehabilitate them at wildlife sanctuaries when possible. Unfortunately, most do not survive the impact.
Paul Groleau, president of Feather Friendly, a company specializing in bird-safe window treatments, believes that more birds die from window impacts than is generally recognized. Greenberg often hears workshop attendees say, “I heard a bird hit my window, but it flew off, so it’s fine.” However, Groleau asserts that approximately 60 percent of stunned birds do not survive. Their delicate skulls make them vulnerable to injury, and if they don’t recover, they might become easy prey.
When CBCM volunteers find deceased birds, they deliver them to the Field Museum, where the specimens become part of an archive Willard has curated for decades. Many are preserved in the museum’s collection, tagged and identified, or at least recorded in a detailed data set documenting window collision fatalities.
The number 10,863 reflects the birds Willard documented in 2023. While the actual number of collisions is likely much higher, this figure represents those the CBCM volunteers found. Greenberg engages thousands in recreating these birds using fabric and glue while educating them about bird collisions through craft, science, advocacy, and social practice.
Starting with a small grant and interns from Syracuse University, Bird Collisions in the Anthropocene began with a list of birds from the Field Museum, basic crafting supplies, and photographs to replicate the species. Greenberg eventually moved to Evanston, Illinois, where she opened a studio to host workshops and process birds sent from across North America.
Workshops have been conducted throughout the U.S. and Canada, totaling over 140 sessions. Materials are available for download on the website, allowing anyone to host a workshop. Popular venues include public libraries and schools. The Cornell Lab of Ornithology, creator of the BirdCast tool, launched a pilot program distributing sew-a-bird kits to New York State biology teachers to help students meet core education requirements.
The hands-on, communal nature of the workshops is vital to the project. Greenberg opens her studio to the public monthly as part of the Evanston Made program, and private gatherings can be arranged. “People get into the flow, no one is touching their phone, and everyone is super concentrated,” Greenberg notes. “They’re working with awkward materials, and it’s a mess, but it’s a good creative mindset.”
Studies on experiential learning indicate it enhances knowledge retention, attentiveness, and experimentation. As participants create birds like house sparrows, dark-eyed juncos, and golden-crowned kinglets, a sense of camaraderie forms. Greenberg provides information on preventing bird collisions, including remediation technologies.
Companies like Feather Friendly offer products for windows, commonly in the form of small vinyl dots. Another option is Bird Divert, which uses clear dots that are hard for humans to see but help birds distinguish glass from nature. Fritted glass, featuring ceramic details baked into the surface, is another solution.
Greenberg appreciates the artistic potential of remediation window coverings and previously invited artist Taro Takizawa to adorn her Evanston studio’s windows with hand-cut vinyl designs. This summer, Greenberg plans a social project to install various remediation dots on her studio’s large windows, complemented by an installation from artist Alice Hargrave, who works with bird call sound waves.
The project has completed 3,451 fabric birds, with an estimated 1,000 more awaiting tagging and cataloging in a handwritten ledger reminiscent of pre-computerized museum records. With the help of interns, each bird is labeled with its species, artist, and origin. Installation opportunities are plentiful.
Eventually, these birds will form a massive “carpet” to emphasize the urgent issue of bird collision deaths and the effectiveness of collective action. Some groups of fabric birds are displayed in exhibitions, such as the Chicago Architecture Center‘s upcoming show, Flyway City, which promotes the creation of more bird-friendly and wildlife-welcoming urban environments.
The exhibition, organized by Studio Gang, features Jeanne Gang, who has advocated for bird-friendly building codes in Chicago. Although Evanston has such an ordinance, Chicago does not, despite several proposals. Greenberg hopes continuous advocacy and information-sharing will inspire similar initiatives across North America.
Flyway City will be exhibited from June 11 to January 3, 2027, in Chicago. For updates on workshops and participation opportunities, follow Greenberg’s Instagram.
