We have all heard how elephants never forget, but it seems that some of our feathered friends also have long memories.
New research suggests that crows can hold grudges for up to 17 years against those who anger or threaten them.
The birds – long considered amongst the most intelligent of the avian species – were also found to be very good at recognising faces.
The study began in 2006 when Professor John Marzluff, an environmental scientist at the University of Washington, put on a scary mask and captured seven crows in a net. Before releasing them unharmed, he put identification rings on the birds’ legs.
Professor Marzluff told the New York Times that he and his assistants would occasionally wear the mask in subsequent years as they walked around campus feeding the resident crows and recording their reaction.
New research suggests that crows can hold grudges for up to 17 years against those who anger or threaten them (stock photo)Â
The study began in 2006 when Professor John Marzluff, an environmental scientist at the University of Washington, put on a scary mask and captured seven crows in a net (stock image of a man wearing a scary mask)Â
On one occasion, Professor Marzluff recalled, he was subjected to aggressive ‘scolding’ caws from 47 out of 53 crows he encountered.
He said that as the number of crows was much higher than the original group that were captured, that the crows somehow learn to recognise threatening humans from their parents and relatives.
After peaking in 2013, the number of aggressive caws started to fall until no scolding calls were logged at all during one walk in September 2023 – 17 years after the experiment began.
As part of the study, members of the research team also used a ‘neutral’ mask resembling Dick Cheney, then vice-president of the US.
Those wearing the Cheney mask fed the crows without subjecting them to any trauma – and were not subsequently subjected to avian abuse.
In another part of the experiment, students used a different set of masks while trapping crows around Seattle.
Volunteers were then asked to wear the masks without knowing which were deemed ‘dangerous’ or ‘neutral’ by the crows.
One volunteer who put on a ‘dangerous’ mask, Bill Pochmerski, said: ‘The birds were really raucous, screaming persistently, and it was clear they weren’t upset about something in general. They were upset with me.’
As part of the study, members of the research team also used a ‘neutral’ mask resembling Dick Cheney (pictured), then vice-president of the USÂ
On one occasion, Professor Marzluff recalled, he was subjected to aggressive ‘scolding’ caws from 47 out of 53 crows he encountered (stock photo)Â
Separately, people living in Townley and Beauval Roads in upmarket Dulwich, south-east London have reported a series of dive-bombing attacks from crows this year.
Local resident Alison Frean, 60, told Mail Online: ‘Last year I was swooped on three times just trying to get out of my car. It was quite traumatising…. I tried to go out again with a bike helmet on.
‘Kids on little scooters are being dive-bombed and people just stay in their houses, looking out.’
Previous studies show that crows’ remarkable intelligence includes the ability to make tools and even count up to four.
