A crow perches on a gravestone in Ukraine.
Don't mess with me. Gleb Garanich/Reuters

One man is on a mission to map bird-on-human aggression around the world.

There’s a reason Jim O’Leary goes outside wearing a hat. That reason was demonstrated last month in Vancouver when he was walking to work and heard a screech, then felt something suddenly swoop over his shoulder.

It was a marauding crow. “Invariably, they attack you from the back and hit your head,” says O’Leary, a GIS instructor at Vancouver’s Langara College. “If you’ve got a hat on it’s a different story. But it’s still kind of terrifying—there’s a SQUAWK! and this bird goes right by you.”

O’Leary takes defensive action when out and about because, as the operator of CrowTrax, he’s read thousands of crowdsourced reports about crows clawing people’s heads. O’Leary debuted the map last year with coworker Rick Davidson as a response to crows dive-bombing folks in front of their building. “There was a crows' nest in a tree, and it was a battleground,” he recalls. “The crows were attacking everybody on both sides of the street. I thought, Is there something we can do about this?

CrowTrax sources crow attacks on humans in Vancouver and all over the world. (CrowTrax)

O’Leary responded in the only way a GIS instructor could: by making a map. With Davidson, he created CrowTrax, a GIS tool that keeps tabs on the whereabouts of Vancouver’s angry crows. Since then it’s gone global, showcasing roughly 4,500 reports from Seattle, Portland, St. Louis, Florida, New Mexico, Guatemala, India, and elsewhere. “I didn’t think it would take off quite like the way it did,” O’Leary says. “People are putting down things that’ve happened [way back] in the past. In a way, it’s kind of like a therapy site where people have the need to tell their stories.”

As the tool reveals, reports of crow-on-human aggression generally occur during a few months in the spring, when the otherwise copacetic creatures become extremely protective of their chicks coming out of the nest. Adult crows will defend their brood by ambushing any human, dog, cat, or rival bird in the vicinity.

If you think getting beaten up by a crow sounds ridiculous, you might need to re-watch the Hitchcock movie. These are large and formidable birds; their assaults are sudden, brutal, and often frightening. (They can also be intense but kind of cute, as seen in the below video of a curious crow.)

“It’s traumatic because it happens unexpectedly and from above,” says O’Leary. “I frequently get reports where they break the skin. They do draw blood at times. I’ve had other reports with women where the talon gets stuck in the hair. That’d be kind of a terrifying thing, if a crow attacks you and then the crow can’t get out of your hair.”

Most of CrowTrax’s mayhem falls inside urban boundaries, which speaks to dense human populations reporting stuff more often but also to the fact crows love cities, which offer protection from wild and human predators. (Hunters don’t often venture to downtown boulevards and plazas to plink at birds, after all.) And some cities frown on crow-control efforts. Vancouver has said it won’t remove crow nests or eggs, instead advising people under bombardment to “take an alternate route or use an umbrella.”

Food waste is everywhere in cities; a hungry crow need only find a trash can to get a nibble of doughnut or old meat. Cities are also more hospitable during wintertime due to the heat-island effect. There’s a reason the numbers of crows are swelling in urban areas—as Ariel Aberg-Riger noted in her illustrated CityLab story this week, recent decades have seen crow populations rise 425 percent in Albuquerque, 122 percent in Sacramento, and 187 percent in Hartford, Connecticut.

That means the future is looking bright for CrowTrax. Indeed, O’Leary plans on conducting some kind of analysis on its trove of data, and at least on other Canadian researcher wants to exploit it as well. “It could be interesting to relate the location of crow attacks to some extra covariate,” says Jean-François Coeurjolly, a Université du Québec at Montréal professor who’d like to use CrowTrax for a spatial-statistics course. “For instance, could we explain the attacks by the density of the population—or even more interesting, by the density of the young population that is more sensitive to using smartphones—or by the proximity to parks?”

O’Leary hopes to solicit more international data soon, but at the moment that poses a burdensome side-gig. “I have to vet every CrowTrax report,” he says. “Some people put in ridiculous things and it takes away the credibility. People say, ‘A crow followed me into the bar and ran away with my girlfriend,’ that sort of thing.”

Here are a few sample incidents that seem more plausible, though:

Montreal, 6/4/17: “I was going to sit outside for my lunch break, as per usual when it is nice out when I was chased by 3 very large crows. I had my hair pulled and the earring pulled out of my ear painfully.”

Toronto, 6/29/17: “THE BACK OF MY HEAD WAS CLAWED AT AND I RAN AWAY IN TERROR”

Portland, 7/23/17: “A crow swooped to attack me on my balcony. Totally scared to water my plants now. Constant cawing all day as well.”

Vancouver, 4/29/16: “This crow terrorizes me. Every time I leave my house and it's around, it tries to jump on me (and has before). It has waited on my car windshield for me when I leave and arrive... ready to pounce. I literally run in and out of my house.”

Has O’Leary encountered any bird-lover blowback for blaming an animal just trying to protect its young, or for trying to further inflame interspecies tension?

“No, because I’m always very careful to say [in interviews] that I do like crows,” he says. “They are a very smart bird. They’re one of the few animals that use tools; they will take a twig and they will hone it, then put it in a crevice to draw out ants. They remember you. They’re social creatures, work together in a team, and are very intelligent. I want to say nothing negative about the crows, except I wish they would not attack us.”

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