Crows Hold Grudges for 17 Years

Seattle resident Gene Carter spotted a murder of crows encroaching on a robin's nest one day, so he grabbed a rake and swung it at the black birds. For almost a year afterward, the crows would shriek at Carter through his house windows and "dive-bomb" him when he walked to his car. They would even wait for him at his usual bus stop, then "dive-bomb me all the way home," Carter tells the New York Times, which reports the harassment only stopped when the computer specialist moved. What he encountered wasn't fun, but it was business as usual for crows, who are known to hold very long grudges. How long? Around 17 years, according to John Marzluff, a professor at Seattle's University of Washington.

In 2006, Marzluff trapped seven crows on the university campus while wearing an ogre mask. He released the birds soon after, then watched to see how they would respond to the sight of that ogre mask. The peak response came after seven years, when about half the crows who encountered the mask issued aggressive caws, indicating they associated the mask with danger, per the Times. Aggressive caws continued but slowly tapered off up to this September, when, for the first time, all crows who encountered the mask appeared to ignore it, the Times reports. According to KUOW, "the birds who were initially captured are all dead, as are most, if not all, the birds who witnessed the initial capture."

Crows belong to the Corvidae family of birds and are often considered some of the most intelligent birds around. Though a crow's brain is only as big as a human thumb, its size relative to its body is comparable to a primate brain, per Thought Co. That's partly why Marzluff calls them "flying monkeys." They can make tools, count out loud, and recognize and remember human faces in a crowd. But their skills aren't perfect. When Marzluff used a control mask of Dick Cheney, a small number of crows cawed at it, possibly mistaking it for the ogre mask. And if crows can mix up masks, they can mix up people. Blond-haired Lynne Peeples tells the Times she was repeatedly attacked by crows after seeing a man with a blond ponytail kicking birds; she wonders if she was mistaken for him. (More animal behavior stories.)