The Crows Never Forget
Crows turn out to spread warnings about one human face through a whole neighbourhood, parent to chick, which is a neat way to talk about how we all learn fears from each other.
- • University of Washington researchers wore a caveman mask while trapping and banding wild crows at five sites near Seattle; a Dick Cheney mask was the harmless control.
- • At one site, about 1 in 5 crows scolded the caveman mask at first; five years later it was 3 in 5, and the scolding had spread at least 1.2 km.
- • Crows that were caught themselves told the masks apart more precisely than crows that only learned from others.
Would a bird remember your face? Not for a day. For five years.
Scientists in Seattle, in the US, tested it. They put on a scary caveman mask, caught some wild crows, put a tiny band on each leg and let them go. Nobody was hurt, but for a crow, being grabbed is terrifying.
Then they walked around in masks again. Watch how the news spread.
Step one: crows that had been caught saw the caveman and went wild. Screeching, scolding, dive-bombing. A different mask? Mostly ignored. It didn't matter who wore it. They even flipped the mask upside down. The crows tilted their heads... and screamed anyway.
Step two: crows that were never caught joined in. They had watched the fuss and learned: that face means trouble.
Step three: chicks learned it from their parents.
At one spot, about 1 in 5 crows scolded the caveman at the start. Five years later? 3 in 5. Three times as many, and most had never been grabbed. The warning travelled more than a kilometre.
Now the twist. The crows that were actually caught were the best at telling the masks apart. The ones who only heard the rumour were sloppier.
Sound familiar? Think how a little kid learns what's scary: not from the dog, but from your face when it barks.