In Canada, there is a city where crows attack people every spring, and residents rely on a live map to avoid them

Picture this: you're walking down a sidewalk in Vancouver, minding your own business, sipping your coffee, and then something smacks you in the back of the head. No warning, no noise; just a straight hit from above. Welcome to crow attack season, a very real, very weird annual event in Canada's Vancouver.

Every spring, roughly April to July, crows all over Metro Vancouver transform into little fighter jets. They swoop. They scratch. Sometimes they draw blood. It’s so predictable on the calendar that a local college instructor has even built an actual live map so people can check which streets to avoid before they leave the house. This CBC News report says the tool, called CrowTrax, was developed by Jim O’Leary, a geographic information systems instructor at Langara College, and fellow instructor Rick Davidson.

Meet CrowTrax, the app tracking the angry birds
CrowTrax is exactly what it sounds like: a crowdsourced map where anyone who gets divebombed can drop a pin and describe what happened. Since its launch in 2016, the map has received thousands of reports. According to this piece from Vancouver Is Awesome, O’Leary now receives about 1,500 reports of “human-crow interaction” every year, with the biggest hotspots being downtown Vancouver and the West End, areas with narrow sidewalks, leafy trees, and lots of restaurant food scraps that crows have grown to love.

This is not a tourist gimmick or folklore for anyone visiting. It’s a well-documented ongoing pattern that locals plan their walks around, just like you would check a weather app before deciding if you need to bring an umbrella. In fact, some West Vancouver residents in the Dundarave neighbourhood have literally put up handwritten signs warning pedestrians about swooping birds, according to a Global News story.

So why are the crows so mad?
Here's the part that actually makes crows look less like villains and more like exhausted parents. Spring is nesting time, and by late April or May, crow parents have fledglings, baby crows that have left the nest but are not good at flying yet. Often, these babies are hopping around on the ground, completely helpless. Naturally, mom and dad crow are on high alert, and anyone who walks too close to a hidden fledgling gets treated like a threat.

Male and female crows take turns dive-bombing passersby to protect their young, and the aggressive phase usually eases up once the fledglings can fly on their own, according to CBC News. As a UBC zoology professor put it simply: It’s less “horror movie” and more “overprotective parent having a rough week.”

Crows never forget a face
Crows are known to possess sharp memories, especially for human faces. In a now-famous experiment, researchers at the University of Washington trapped and banded wild American crows while wearing a specific “dangerous” mask. Years later, those same crows, and even crows that had never been personally trapped, would scold and mob anyone wearing that same mask. In the peer-reviewed study ‘Lasting Recognition of Threatening People by Wild American Crows,’ led by Dr. John Marzluff and published in Animal Behavior, researchers found that crows recognized the “threatening” face for at least 2.7 years after the initial encounter.

Even more impressive, a follow-up study found that crows not only remember threats themselves, but they also teach other crows to recognize the danger too, essentially passing the information down through the flock. The research, ‘Social learning spreads knowledge about dangerous humans among American crows,’ published in Proceedings of the Royal Society B, suggests that crows can identify people who might harm them by both personal experience and social learning.

What to do if you're ever caught in the crossfire
If you ever find yourself in Vancouver during crow season, locals swear by a few simple tricks: wear a hat, carry an umbrella, and whatever you do, don't run. O’Leary also says that if you run, a crow will think that you are an active threat worth chasing, but if you walk away calmly, the encounter will usually end sooner.

It’s almost absurd, an entire city changing its daily rhythms for the sake of birds, but it’s a small, oddly endearing reminder that wildlife and city life are still intertwined, even in a modern North American metropolis. So if you are planning a trip to Vancouver this spring, maybe just check the map first.