As deadly bird collisions with buildings mount, cities look for solutions

On a crisp fall evening last October, close to 1,000 birds died after flying smack into McCormick Place, a convention center in Chicago abutting Lake Michigan. The building’s massive glass facade was lit up, disorienting birds who were already flying low to the ground from rain earlier that day.

The event was shocking. For members of the Chicago Bird Collision Monitors, it was the worst day in their 40-year history. Instead of picking up injured birds, monitors were filing garbage bags. 

But what wasn’t shocking to the volunteers walking around Chicago that day was the cause of the carnage. The story of how the birds met their demise is all-too-familiar to bird groups and the Chicago Bird Collision Monitor: According to recent studies, buildings in the U.S. kill more than 1 billion birds each year (although some studies put the number lower).

Unchecked, that number could grow worse, said Tara Zuardo, senior advocate at the Center for Biological Diversity. Already, U.S. bird populations have declined by almost a third, or nearly 3 billion birds, since 1970, according to a large-scale analysis of national bird surveys. Second only to cats, glass buildings are among the biggest killers of birds. 

Last week, Zuardo’s group and more than two dozen other bird and wildlife conservation organizations from 23 states sought to forestall further bird declines by filing a legal petition asking the U.S. Fish and Wildlife Service to establish a permitting process for commercial buildings to protect birds from deadly window collisions.

“More than 1 billion birds every single year are injured and die from these collisions. I would call that egregious,” Zuardo said. “Some of these birds are already endangered. The federal government is responsible for preventing take.”

The petition proposes that the agency create a permitting process under the Migratory Bird Treaty Act that would require building owners to use proven measures to reduce collisions, such as films, curtains or other means that make glass visible to birds.

Zuardo calls the request “low-hanging fruit.” She says the agency started drafting migratory bird protection rules a few years ago, but abandoned the effort last December. “I think we are on the precipice,” she said. “The regulatory structure exists. It is really past time for U.S. Fish and Wildlife to take action.”

The regulatory structure that Zuardo is referring to is the permitting process administered to reduce harm to bald and golden eagles. Last week’s petition asserts that if the agency can create a permitting process for eagles, it can also do so for migratory birds.

Following last October’s incident at McCormick Place, the owners of the building decided to take action. They’ve begun installing decals with little polka dots on the windows in the hopes of reducing bird collisions with the convention’s two football fields’ worth of glass.

According to the American Bird Conservancy, some bird-friendly alternatives to traditional glass include angled glass, ultraviolet patterned glass and opaque glass. Alternatively, developers can add netting, screens, cords or decals to make a window more bird-friendly.

Increasingly, cities and states from San Francisco to Minnesota are establishing ordinances that call for these alternatives. Earlier this summer, Portland, Maine, adopted bird-friendly requirements for buildings of more than 10,000 square feet.

In Chicago, where the issue is particularly acute as it is located along a key bird migration route called the Mississippi Flyway, the city has a voluntary ordinance in place that encourages buildings to limit their use of transparent and reflective glass, use patterned glass in high-risk areas and reduce the interior lighting that can lure birds to their death.

In 2021, Illinois Gov. JB Pritzker took it a step further and signed a law requiring new state-owned buildings to incorporate netting, screens, shutters and other bird-friendly features.

These ordinances are either voluntary or have low compliance, according to Zuardo. While she praises the policies, she pointed to three ordinances in California that go a step further and mandate bird-friendly designs for new construction. 

Oakland, for example, got the ball rolling in 2013 when it became the third major U.S. city to adopt bird safety building standards. Its ordinance, among other things, mandates that new buildings apply bird-friendly glazing to at least 90% of windows and glass between the ground and 60 feet above ground, turn out nighttime architectural lights, install motion sensors or timers so that they can be programmed to turn off between 11 p.m. and sunrise, and minimize roof antennas and other rooftop structures that create additional collision risks.

The ordinances in Alameda and Emeryville mandate similar bird-friendly procedures on new construction. The American Bird Conservancy highlights these ordinances as best practices. “My only complaint,” Zuardo said of them, “is that they only apply to new buildings.”

One approach that has been around for a while is the Lights Out program. The Chicago Audubon Society launched just such a program in 1999, building on an effort in Toronto. Lights Out programs challenge tall buildings to dim or extinguish lobby, exterior and decorative lighting between 11 p.m. and sunrise during migratory seasons—March through May and September through November—and to revise layouts that might be confusing to birds, such as green roofs that might have tall trees.

Cities could also consider encouraging bird-friendly approaches through tax incentives, Zuardo said, especially as it pertains to residential buildings—the next front in efforts to reduce bird collisions. But Zuardo says that getting the federal government to move on the issue is key to inspiring more cities and states to adopt bird-friendly policies.

“We already have the permitting process in place,” Zuardo said. “It is time for U.S. Fish and Wildlife to take this step. And when they do, I think you’ll see a lot of states and cities step up.”