GabyElephants may have the reputation for never forgetting, but crows aren’t far behind. A new study reveals that crows can hold a grudge for up to 17 years against people who anger or wrong them. These birds, already known as some of the smartest in the animal kingdom, also show impressive facial recognition. What did researchers uncover?
In the initial phase of the study in 2006, lead researcher Professor John Marzluff of the University of Washington put on a frightening mask and trapped seven crows in a net. Before releasing them unharmed, he attached identification bands to their legs. Marzluff said that in the following years he and his assistants sometimes wore the same mask while walking around campus, feeding the local crows, and watching how they reacted. On one occasion, 47 of the 53 crows he encountered during a research walk responded with aggressive, “cursing” caws. That number was far higher than at the start of the experiment. Marzluff speculated that the crows had taught their peers to recognize people in threatening masks.
After peaking in 2013, the number of aggressive caws directed at people wearing the “dangerous” mask began to decline, and by September 2023 not a single hostile squawk was recorded during one walk. That marked 17 years since the experiment began. During the study, researchers also used a neutral mask. People wearing the neutral mask fed the crows without harming them and subsequently did not face harassment. For the second part of the experiment, when the team trapped crows on the outskirts of Seattle, they used a different set of masks. The scientists then asked volunteers to wear masks without telling them which ones the crows had associated with danger and which ones had been neutral. One volunteer who wore the “dangerous” mask said, “The birds were very noisy, constantly squawking, and it was clear they weren’t upset about something in general. They were upset with me.”
Meanwhile, residents of the upscale Dalwich neighborhood in southeast London reported a series of dive-bombing attacks by crows this year. Local resident Alison Frean, 60, told the Daily Mail, “Last year, I was attacked three times just trying to get out of my car. It was quite traumatic… Eventually, I tried going out in a bicycle helmet.” Previous studies have shown that crows can make tools and even count up to four.
