To the untrained eye, one crow may look the same as any other. However, a new study published in the Proceedings of the National Academy of Sciences demonstrates that crows can remember human faces and past interactions.

Dr. John Marzluff, an avian ecologist and professor at the University of Washington, led a team of researchers to study the ability of crows to recognize human faces. It was the first study to use brain imaging on wild animals behaving normally.

Marzluff’s team members captured wild American crows (Corvus brachyrhynchos) while wearing a “threatening” mask. The mask was a latex copy of an actual face (one of Marzluff’s graduate students) with a neutral expression, but the stressful act of capture represented threatening behavior. Crows were then kept in a lab setting and fed and cared for by a researcher in a “caring” mask, molded from a different face.

Captive birds were then shown images of either a researcher wearing one of the masks or an empty room. Immediately after viewing the stimulus, crows were anesthetized and placed in a PET scan.

Analysis of brain activity collaborated with observed behavior. Crows presented with threatening masks had brain activity in regions associated with fear and blinked less while observing the stimulus. Among the areas elicited by the caring mask were those associated with hunger, suggesting the crows had connected their caregivers with feeding.

As for the ability of crows to recognize individuals of other species, Marzluff says “there is anecdotal evidence for cats and dogs,” whereas the uniformly predatory red-tailed hawk always produces the same response: flight.
Web Bonus: During my interview, Marzluff discussed an earlier experiment conducted in the wild. This experiment involved mostly negative stimuli; the researchers captured and released crows while wearing masks. Marzluff returned to the same site over a period of seven years and the crows continued to recognize and attack anyone wearing the masks. Even crows who had never been captured learned socially to attack the masked scientists. This cruder version of the experiment simply used store bought masks: one a cave man and one of former Vice President Dick Cheney.

Sources:

Phone interview with Dr. John Marzluff (9/19/12).

Marzluff J et al. (2012) Brain imaging reveals neuronal circuitry underlying the crow’s perception of human face. PNAS. doi: 10.1073/pnas.1206109109

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