Crows Can Recognize Human Faces and Hold Grudges for Years Against Specific People

If you have ever wronged a crow, it might remember. John Marzluff, a wildlife biologist at the University of Washington, demonstrated in a series of experiments that crows can identify and remember individual human faces — and warn other crows about you.

The experiment: researchers wore distinctive masks while trapping crows for banding. The crows that were captured began squawking and dive-bombing anyone wearing those masks. More remarkably, other crows that had not been trapped learned the threat and joined in the harassment. The behavior persisted for over 5 years, even when only the masks (and not the original researchers) reappeared.

How Smart Are Crows, Really?

• Tool use: New Caledonian crows make hooked sticks to extract grubs — a level of tool manufacture rivaling great apes
• Counting: They can count up to about 30, and understand the concept of zero
• Reasoning: They solve multi-step puzzles previously thought to require primate intelligence
• Memory: They remember locations of thousands of food caches for many months
• Social complexity: They have communal funerals, group warnings, and family-based learning

The Cultural Dimension

What is most striking is the social transmission. Crows learn from other crows. A young crow that has never been threatened by a human can be raised by parents who teach it to fear specific faces. Crow knowledge has a kind of cultural memory — passed down generations, carried by individual birds, and updated continuously based on experience.