The Washington PostDemocracy Dies in Darkness

Crows took over a Silicon Valley city. Officials hope green lasers will get them to leave.

Crows perch in Sunnyvale, Calif., one of multiple U.S. cities dealing with large roosts of the birds. (KPIX)
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When Sunnyvale, Calif., Mayor Larry Klein goes out for his morning jog downtown, he is transported into a scene from Alfred Hitchcock’s 1963 film “The Birds,” in which flocks take over a coastal California town, perch and glare at residents, and go on the attack.

Perhaps the Sunnyvale crows are not quite that sinister — these birds don’t attack people — but they sure are annoying, Klein told The Washington Post in an interview. They perch in trees and squawk in an early dawn cacophony that rouses residents from their sleep. They also poop in great volumes on the sidewalk.

“I'm often running far into the middle of the street just to make sure that I and my dog aren't going through the white sidewalk, which has been coated” in feces, Klein said.

For going on six years, Klein said, the crows have made something of a home in downtown Sunnyvale, a small city in the heart of Silicon Valley, less than an hour’s drive south of San Francisco. At first, the crows numbered in the high dozens. But the group has since swelled to more than 1,000, a number Klein considers a nuisance.

When the birds first appeared, the city hired a falconer to scare them away using a hawk, with limited success, Klein said. The city has also put reflectors in the trees that are supposed to repel the crows. But that, too, has not done much.

“They're very intelligent birds,” Klein said. “I wish we could reason with them to just disperse a little bit.

Instead, the city is taking a different tack: green laser pointers. Starting next week, Klein said, several city workers will head out for two hours around dusk and harass the birds with the lasers, hoping they’ll fly away and roost somewhere else. The team will also carry around a boombox to play distressed crow noises, which may scare the birds. A third measure involves hanging crow effigies in the trees, but Klein acknowledged the crows may soon wise up to the ruse and ignore them.

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Klein said the city had not yet calculated the cost of the program, but he said it was much cheaper than the “thousands and thousands of dollars” the city has spent spray-washing crow poop off the sidewalk. The laser pointers cost $20 apiece, he said, and the boombox belongs to a city staffer.

Similar efforts have been attempted in other cities, some with roosts far larger than the one in Sunnyvale. Officials in Trenton, N.J., have employed lasers, pyrotechnics and spotlights to disperse some 20,000 crows that settle downtown each winter, reported. In 2014, Penn State University employed a combination of lasers and loud fireworks, attempting to displace the roughly 3,000 crows that roost on campus, though the birds continue to come back, reported.

Scientists believe crows mainly roost in groups as protection from predators, said Douglas Wacker, an associate professor who studies crows at the University of Washington at Bothell. For one thing, there is “safety in numbers” in roosting together, he said. It can also act as an “early warning system” in which one crow can tell the others if an area is unsafe. Crow roosts can range from several hundred to 2 million, according to the Cornell Lab, and in recent decades, they have taken place in urban areas.

There’s a fairly simple explanation for why crows are flocking to cities, said Kaeli Swift, a postdoctoral wildlife researcher at the University of Washington and an expert on crows.

“People and crows have a lot of overlapping interests in how they like their environment structured,” Swift told The Post. “So any time we cut down intact tracts of forest and replace it with neighborhoods, we are creating a much more appealing environment for a crow.”

Well-lit areas help the birds avert predators, and they build their nests in large trees that dot an urban landscape, Swift said. Crows also like industrial lawns that provide a steady source of bugs to eat, as well as the “predictable garbage buffets” humans provide.

“Downtowns in a town like Sunnyvale are designed for crows,” she said.

Yet Swift expressed wariness about efforts to remove the roosts. Often, the strategies don’t work, she said. And if they do, the effects are rarely permanent.

“The reality here that faces municipalities is that the crows aren't doing something weird,” she said. “This isn't caused by the pandemic. This isn't unusual behavior, which means it's going to happen somewhere.”

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Wacker said multiple techniques would probably have to be used “over a longer period of time” for a city to stand a chance at displacing a crow roost. He cited a 2002 study that found lasers alone were ineffective. While the crows in the study flew away when researchers shined the lasers in their direction, the birds returned after 15 minutes.

“If there was a magic bullet to get rid of these crows, somebody would have already known what it was and would be doing it right now,” Wacker said.

There is another solution, he said: “People largely just need to learn to start living with nature versus against nature.”

Swift agreed, noting that it is important for cities to invest in designated green spaces where crows can hang out. She also suggested Sunnyvale might think about making the crows a part of its identity.

Similarly, Wacker referenced a Twitter poll by Sunnyvale’s vice mayor asking if anyone would come to an annual crow festival in the city. Out of 452 votes, more than 87 percent said they would.

“It would probably bring money in,” Wacker said. “People would come and … you could bring in [experts] to give a talk, and it probably would be quite popular.