They both never forget.
New research has determined that crows will remember distinct human faces for five years or more, especially if it’s the face of a human who has threatened or attacked them. It isn’t just the victimized crow who holds a grudge, either. Other crows in the area will learn to be wary of the dangerous human even if they weren’t personally harmed.
Discovery News reports on the findings, which appeared in a recent issue of the Proceedings of the Royal Society B. Study co-author John Marzluff and his colleagues bagged, tagged and released between 7 and 15 wild crows at different research sites around Seattle. The team did this while wearing special masks. Upon release, the individual crows immediately began making harsh, agitated cries, commonly known as “scolds.”
The scolding “attract[s] other crows who are nearby to join in the mob,” Marzluff, a professor at the University of Washington’s School of Forest Resources, told Discovery News. “The mob of 2 to 15 birds hounds us, sometimes diving from the sky to within a few meters or less — this pursuit lasts about 100 meters (328 feet) as we walk away.”
Later, the team traveled to different areas and donned the same masks. They soon found themselves surrounded by scolding crows — but not the same crows originally captured. This suggests that the big, black birds learn from social interaction and association, not just direct experience. Marzluff and his colleagues were even scolded by crows a mile away from the original site.
If a crow survives to adulthood, it can live between 15 and 40 years in the wild. From the evidence gathered by Marzluff and his team, it’s likely that they remember such strong associations for their whole life.
At the very least, the study “shows the memory lasts at least five years and counting,” Marzluff told Discovery News. He emphasized that crows are notoriously smart birds. “Others have shown that some crows make and use tools, forecast future events [and] understand what other animals know. These are all advanced cognitive tasks shown by only a few animals.”
“In our case [we know that they] learn from individual experience as well as by observing parents and peers,” he added.
So the next time you think about bothering a crow, don’t forget this study — after all, the crows certainly won’t!
Photo credit: malfet_
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