Sister Cities Cafe Makes Windows Safer for Birds

Windows of any size can kill birds, but those at Sister Cities Cafe in Center City were particularly lethal. “It’s essentially a glass cube with three sides that are full windows top to bottom,” says Stephanie Egger, a volunteer with Bird Safe Philly. “The problem here is twofold: its transparency, so the birds can see actual habitat through the glass, or its reflective issues.” The cafe is surrounded by trees, an artificial stream, and a pollinator garden, all of which look to a bird like nice places to land.

Indeed, a songbird smacked into the glass and fell to the ground, dead, as workers finished installing a bird-protective window film at the cafe. “They were saving the windows with the logo [of the cafe, above the door] and the doors for last so people could get in and out,” says Stephanie Egger, a volunteer with Bird Safe Philly. “Ironically, a black and white warbler struck the logo window and dropped to their feet during the installation —pure evidence for why this is necessary.”

The warbler was one of an estimated 599 million birds that die in the U.S. each year by collisions with glass windows, confused by habitat they either see through the glass or reflected by it. Window collisions rank only behind house cats (which kill about 2.4 billion birds annually) as a top way that humans cause wild bird deaths.

Bird Safe Philly dates back to October 2, 2020 when volunteer bird-window collision monitor Stephen Maciejewski found hundreds of dead and stunned birds on a particularly deadly morning. Most migrating songbirds travel at night, and they can be drawn into cities by artificial lights, particularly when a low cloud ceiling results in poor visibility. Such conditions led migrating birds to land in the city at dawn, where they then ran into windows.

The shocking images of piles of dead warblers taken by Maciejewski led local conservation organizations to partner with commercial building owners to form Bird Safe Philly. The partnership launched a campaign to encourage building managers to turn down lights at night during spring and fall migration. It also organized additional window collision monitoring to identify particularly lethal windows.

At Sister Cities Cafe, volunteer bird window collision monitors documented 78 collisions in which birds died or were stunned from 2021 through the spring of 2023, according to Maciejewski. That number understates the true total, according to Egger. Bird Safe Philly volunteers check the ground near buildings during spring and fall migrations, when most collisions take place, but birds still run into glass other times of the year.

“The science [of window collisions] is known. The way to solve it is well known,” says Leigh Altadonna, president of Wyncote Audubon. Windows can be made safer for birds by hanging netting or string in front of the glass, or by adding patterns directly to the surface.

Egger says Bird Safe Philly approached the Center City District, which owns the cafe building, in the spring of 2023 to discuss how they might be able to reduce bird collisions there. They settled on a window film with a pattern of dots produced by Feather Friendly, a Canadian company. Installation took place in September, conducted by Street Media. The project cost about $8,000.

“I just feel like it’s a great new poster child for the city,” Egger says. “We can coexist with birds and protect them as much as we can. And it looks great.”