Crows Hold Grudges and 'Pass Down' Their Hatred: A 17-Year Mask Experiment

In 2006, biologist John Marzluff from the University of Washington donned a caveman mask and captured and banded seven American crows on the Seattle campus. Unexpectedly, this experiment turned one specific mask into a warning symbol for the crows for 17 years. From then on, whenever someone appeared wearing the same mask, the crows would issue warning calls and even gather their companions to drive them away. Even more surprisingly, the warning behavior wasn't limited to the crows that personally experienced the capture; other crows learned to recognize the face through observation, and even young birds born years later joined the warning ranks. This indicates that crows not only possess excellent facial recognition abilities but can also transmit danger information through social learning. In September 2023, about 17 years after the experiment began, Marzluff walked through the campus again wearing the mask, only to find that the crows no longer issued warnings. This might be related to the gradual death of the older crows who experienced the initial event and the failure to continuously pass down the warning behavior. This research reveals that animal memory is not just individual experience but can also spread through observation and imitation within a group. However, as individuals familiar with this experience gradually disappear, the long-standing warnings may also fade away. The story of the crows makes us rethink animal intelligence and reminds us that memory, learning, and cultural transmission are not exclusively human abilities. Wow, holding a grudge for 17 years! No wonder they say crows are vengeful. Spreading that hatred to the whole group for revenge, that's intense😮