Crows remembered one dangerous mask for eight years

The man in the caveman mask came to catch crows. On a university campus, he and his team pulled on the rubbery, heavy-browed face, grabbed seven birds, and then let them go. It was not a procedure the birds enjoy, and the researchers made no effort to look normal while doing it.

John Marzluff, a University of Washington professor who studies crows and their relatives, wanted to test whether the birds could learn a single dangerous human face. For comparison, his team also walked the campus in a mask of former Vice President Dick Cheney, and did nothing harmful while wearing it.

At first, the crows did not care. Before any captures, Marzluff showed, neither mask drew much response. Weird looking people were not unusual on campus, and the birds largely ignored them both.

That changed after the seven birds were caught. When someone later walked the campus wearing the caveman face, crows scolded loudly, dived at him, and chased him down the path. They recognized the face upside down, with a hat, and without one. When the same walker wore the Cheney face, or no mask at all, the birds stayed quiet.

The point was survival. Crows live around people with different attitudes, some who feed them and some who chase them, so telling one person from another matters.

What surprised Marzluff was what happened next. Over eight years, scolding of the caveman roughly doubled, and it continues today. Almost every bird in the mob had never been touched or harmed by the masked catcher. Many of the birds scolding now were not even born when the first captures happened seven and a half years earlier.

They had learned by watching. A young crow sees older birds screaming and diving at that one face, and joins the attack. The grudge spreads from bird to bird, without each bird having to be caught itself.

Eight years later, the caveman still cannot walk in peace.