The intelligence of the corvid family—a group of birds that includes crows, ravens, magpies, rooks and jackdaws—rivals that of apes and dolphins. Recent studies are revealing impressive details about crows' social reasoning, offering hints about how our own interpersonal intelligence may have evolved.
One recent focus has been on how these birds respond to the sight of human faces. For example, crows take to the skies more quickly when an approaching person looks directly at them, as opposed to when an individual nears with an averted gaze, according to a report by biologist Barbara Clucas of Humboldt State University and her colleagues in the April issue of Ethology. The researchers walked toward groups of crows in three locations in the Seattle area, with their eyes either on the birds or on some point in the distance. The crows scattered earlier when the approaching person was looking at them, unlike other animals that avoid people no matter what a person is doing.
Clucas speculates that ignoring a human with an averted gaze is a learned adaptation to life in the big city. Indeed, many studies have shown that crows are able to learn safety behaviors from one another. For example, John Marzluff of the University of Washington (who co-authored the aforementioned paper with Clucas) used masked researchers to test the learning abilities of crows. He and his colleagues ventured into Seattle parks wearing one of two kinds of masks. The people wearing one kind of mask trapped birds; the others simply walked by. Five years later the scientists returned to the parks with their masks. The birds present at the original trapping remembered which masks corresponded to capturing—and they passed this information to their young and other crows. All the crows responded to the sight of a researcher wearing a trapping mask by immediately mobbing the individual and shrieking.
Although humans take it for granted, this type of social learning is cognitively complex and rare in the animal kingdom, according to Marzluff. “It's one thing to learn from one's own experience and another to observe that happening to other individuals and infer it could happen to you,” he explains.
A crow recognizes human faces using the same visual pathways in the brain as humans do. A 2012 study using PET scans found that when crows viewed human faces that they associated with threat or care, the birds had increased activity in the amygdala, thalamus and brain stem—areas related to emotional processing and fear learning. In response to threatening faces, areas that regulate perception, attention and fleeing also lit up.
The similarity to human brain activity and the parallels in social intelligence in general are significant because they may have evolved after our last common ancestor existed 300 million years ago. That would make our species' similarities a case of convergent evolution, when two vastly different organisms develop the same traits independently. “Evolution has arrived at the same solution again and again,” says Alex Taylor, a crow expert at the University of Auckland in New Zealand.
Remarkable Abilities of Birds
The woodpecker finch from the Galápagos Islands can use a twig to pry insects out of bark.
Kea parrots are keen problem solvers and can use sticks and string to push or pull food into reach.
An African grey parrot named Alex learned a vocabulary of more than 100 words and the labels of more than 35 objects. He could use words correctly in a sentence, saying “no,” “come here,” “I want a banana,” and “wanna go back,” when he was tired of testing and wanted to go to his cage to rest.
Siberian jays can modulate their alarm calls to warn their peers whether a nearby hawk is perched, searching for prey or attacking.
Ravens can share information about the location of a carcass.
African honey-guides direct humans to bees' nests, which contain honeycomb. When their unwitting accomplices crack open the nests, the birds scavenge leftover treats.
Scrub jays have strong spatial memory and can relocate food they have witnessed others hiding.
Pigeons can learn to distinguish a painting by Picasso from one by Monet.
As with crows, magpies can recognize a specific face out of thousands.