Crows’ excellent memory helps them tell human friends from foes

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They may not crow about it, but if you get on the wrong side of them, they’re not going to forget it in a hurry.

Crows have an excellent memory for human faces, a study has revealed.

They can tell the difference between a friendly face and a dangerous one, and can warn each other which is which.

And the birds – which are said to be as intelligent as chimpanzees – will remember the face of someone who poses a threat to them for at least five years.

Dr John Marzluff, of the University of Washington, said: ‘Our findings add to the evolving view of large-brained, social and long-lived birds like crows being on a cognitive par with our closest relatives.’

A team of scientists from the university exposed crows in Seattle to a ‘dangerous face’ by wearing a mask while trapping, banding and releasing birds at five sites.

Over a five-year period after the trapping had stopped, they found that the mask received an increasingly hostile response from birds in the area – suggesting that the captured birds had been able to warn others.

Dr Marzluff added: ‘Because human actions often threaten animals, learning socially about individual people’s habits would be advantageous.

‘The number of crows scolding the dangerous mask continued to increase for five years after trapping, as expected if social learning or social stimulation were present.

‘As we conducted trials, walking with the dangerous mask along the route, our actions presented opportunities for crows to observe or be stimulated by scolding.

‘The number of crows encountered was consistent across trials, but the number that scolded the dangerous mask increased steadily.’