A Video Captures the Dreadful Toll Window Strikes Take on Migrating Birds

Grisly visuals from New York City show mass bird death, but they're just a glimpse of what happens in cities nationwide.

Melissa Breyer had a bad feeling. On Monday evening, she received a local alert through BirdCast, a tool that predicts bird movements based on radar: More birds than usual would be making their way that night through New York City and its gauntlet of skyscrapers. Breyer, who spends five mornings a week during spring and fall migration picking up birds that have crashed into buildings as a volunteer collision monitor for NYC Audubon, knew not all of them would make it.

Breyer wanted to be prepared for the worst, so she packed extra bags—paper for injured birds, and plastic for dead ones. She arrived at the World Trade Center complex, a usual monitoring spot, around 6:15 on Tuesday morning. As she neared, she saw small bodies dotting the sidewalk. “Usually, I approach a building, and maybe I'll see a bird or two, but I saw more birds than I could count for as far as I could see,” Breyer says. “I just saw birds everywhere. Just everywhere.”

An average day in migration season might find Breyer picking up around 20 strike victims. But by the end of her shift that morning, she’d filled her bags with 226 dead birds. Of those, she found 205 at 3 World Trade Center and 4 World Trade Center alone. Others were too mangled to collect or out of reach on glass awnings, where she photographed them to count later. Breyer also took 30 injured birds to Wild Bird Fund, a wildlife rehab center. While collecting the bodies, she took a short video and posted it to Twitter.

Breyer’s video is hard to watch, but similarly gruesome scenes unfold off-camera in metro areas nationwide. City lights can disorient migrating birds, causing them to hit buildings or become exhausted from flying around in confusion. And birds may try to fly through glass, not understanding that what they’re seeing is just a reflection. Between 90,000 and 230,000 migrating birds die from collisions with glass in New York City each year, according to NYC Audubon. Nationwide, the death toll is as high as 1 billion

NYC Audubon has been monitoring these incidents through Project Safe Flight since 1997 to help reduce future collisions. The group uses volunteer-collected data to make their case that building managers should dim lights at night or fix reflective glass. Volunteers don’t typically encounter so many casualties at a single site, but scenes like the one Breyer witnessed are not unheard of.

“We tend to get maybe one or two of these big mass mortality events a year, and they seem to be correlated with a heavy pulse of migration paired with certain weather patterns, like low cloud ceilings,” says Kaitlyn Parkins, associate director of conservation and science with NYC Audubon. “I suspect the storm that we had the night before likely had something to do with it as well.”

In a sad irony, Tuesday's incident arrived just after NYC Audubon staff and volunteers stayed up all night to protect migrating birds at the World Trade Center site. Each year, the group monitors birds that are attracted to—and can become disoriented by—the beams of the Tribute in Light, an annual art installation to honor those killed on 9/11. When more than 1,000 birds gather in the beams, the lights are shut off temporarily to give the migrants time to disperse and continue their journeys. Parkins says the Tribute in Light hasn’t caused any bird deaths so far, thanks, at least partially, to this monitoring.

Parkins and other advocates note that simple actions can help to reduce bird collisions. Building managers can turn off non-essential lighting during migration. Individuals, too, can turn out lights in their homes and at work. But with the large number of artificially lit buildings in New York City, Parkins says solving the problem will require a combination of collective action and policy change.

Along with turning off lights, modifying windows can also prevent bird deaths. In 2019, New York City passed a bill that required bird-friendly materials, such as dotted patterns or tinted glass, on the lower 75 feet of all new buildings. Similarly, the national Bird Safe Buildings Act would require that any new or significantly altered federal buildings use bird-safe designs. The bill passed the House last year, and supporters are hoping it will gain traction in both chambers of Congress after it was reintroduced in March. “It would set a precedent,” Parkins says. “And I think that's the most important part.”

For existing buildings, one solution is to retrofit windows with treated glass that deters collisions and to turn off bright lights. Collision data points to hotspots in New York where birds consistently crash into windows. Rita McMahon, director of Wild Bird Fund, calls these places “killer towers.” These include the World Trade Center complex and Circa Central Park, among others with facades made largely of glass.

Silverstein Properties, the developer that oversees 3 World Trade Center and 4 World Trade Center, said in a statement to Audubon that the company is grateful to NYC Audubon and other advocates for bringing the issue of bird collisions to their attention. “We care deeply for wild birds and protecting their habitat in the five boroughs,” a spokesperson said in an email. “Understanding that artificial night-time lighting in general can attract and disorient migrating birds, we are actively encouraging our office tenants to turn off their lights at night and lower their blinds wherever possible, especially during the migratory season.” 

Thanks to collision monitors and wildlife rehabilitators, some of the window-strike victims will get a second chance: Wild Bird Fund tweeted that it was caring for 74 birds injured in collisions Tuesday. The rehab center doubled its workers on Tuesday in anticipation of a large influx of birds, which they gave food, water, and anti-inflammatory medication. Already, some of these birds have been released, McMahon says.

At the same time, Breyer thinks it’s necessary for the general public to understand how many birds die preventable deaths as they navigate cities.

“I think awareness is really, really important, especially on such a bad night,” Breyer says. She took the video so that she could have a record of that day’s carnage. “It's not something that your brain really wants to allow you to remember.”