May 17, 2011 at 3:38 PM ET
Add the black-billed magpie to the list of birds that can recognize individual humans who pose a threat, scolding them when they approach, according to a new study.
The birds are part of the crow family, among the most intelligent animals. Previous studies have shown, for example, that crows can wield tools to find food and American crows have been shown to recognize humans who threaten their nest or captured them.
Until now, however, experimental evidence was lacking that magpies would do the same.
This changed in 2009 when Won Young Lee, a doctoral student at Seoul National University in Korea, was constantly taking eggs out of magpie nests for a long-term survey project and started to be followed and scolded by the nest owners.
He tried to fool the magpie by giving his cap to another person. "This did not work. When I moved away, the bird followed me rather than the fellow observer wearing my cap," he said in a news release.
The researchers followed up on this finding with a controlled experiment. A pair of humans, a climber who went up to nests and a non-climber, wearing the same clothes, were presented to the magpies. All the magpies showed aggression to the climbers, but not the non-climbers.
The researchers suggest the birds learn to recognize the threatening humans by vision, learning over time to distinguish individual faces. If so, magpies would be most likely to recognize humans in urban settings, a theory the team plans to test.
The findings have been accepted for publication in the journal Animal Cognition.John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).