Can crows recognize and remember individual human faces?

Answer

In University of Washington studies led by John Marzluff, crows scolded people wearing a mask that was worn when the birds were trapped, and kept doing it for years while mostly ignoring other masks.

Context

The research began in 2006 at the University of Washington. Seven crows were trapped, banded and released by researchers wearing a threatening mask, while a neutral mask, a mask of former US vice president Dick Cheney, was used as a control and worn by people who fed crows without harming them. The birds learned to treat only the threat mask as dangerous.

The response outlasted the original captives. Birds that had never been trapped also scolded the threat mask, which suggests that crows learn about danger from others, through observation or calls. On one later campus walk, 47 of 53 crows scolded the person wearing the mask. Scolding peaked around 2013 and then faded, and on one walk in September 2023, 17 years after the start, no scolding crows were heard.

A 2012 study in PNAS imaged crow brains and reported circuitry involved in perceiving human faces, with threatening faces engaging regions linked to fear and learning.

The word grudge is a human shorthand. What the work shows is learned recognition of a specific threat and a long-lasting avoidance or mobbing response, and the studies do not claim that crows feel resentment as people do.