Crows Hold Grudges and Never Forget Your Face

Upset a crow, and you may be remembered for a very long time. In a long-running study at the University of Washington in Seattle, wild crows learned to recognise one particular human face, linked it to a bad experience, and went on scolding it for years. The birds even passed the grudge on to others that had never seen the original event. It is one of the clearest demonstrations that crows notice individual people, and that their memories are far longer than most of us would guess.

The project began in 2006. Researchers wore a mask designed to look threatening, a rubber caveman face, while they trapped wild crows, fitted them with leg bands and released them unharmed. As The Conversation reported, the team also used a neutral control mask so they could compare reactions, and carried out the work at five sites. The idea was simple: if crows really recognised faces, they would react to the caveman mask and ignore the other one. On the university campus itself, seven crows were trapped and banded by a researcher wearing the caveman mask.

Afterwards, people walked through the crows’ neighbourhoods wearing the masks while doing nothing threatening at all. The crows did not care about the neutral face. The caveman face was another matter. According to the university’s Urban@UW programme, on one later walk wearing the dangerous mask, 47 of the 53 crows encountered scolded the wearer loudly, far more birds than had ever been trapped. The crows had not only remembered the face; they had spread the word.

That spread is the most surprising part of the study. At one site, The Conversation reported, about 20 percent of crows reacted angrily to the caveman mask shortly after the trapping; five years later, the figure had risen to 60 percent. Young crows scolded the mask on their own, having learned from their parents that it meant danger. Researchers describe this as social learning passed down the generations, so a bad afternoon in 2006 became family knowledge for birds hatched long afterwards.

How do we know how long it lasted? Because the researchers kept checking. The university reports that the grudge held for about 17 years: by September 2023, on a masked walk across the campus, not a single scolding crow was heard. The memory had finally faded from the flock. Even so, that is an extraordinary length of time for a wild bird to hold onto a single human face.

The lesson is not that crows are simply vengeful, but that they pay close attention. As The Conversation put it, crows possess an unusually good memory for human faces linked to a stressful event, and a warning learned by a few birds can travel through a whole community of them. So if crows live near you, it is worth being a calm and predictable neighbour. They may already know your face, and they are very good at telling their families about it.