Crows and Other Species of Birds Remember and Share Information About Dangerous Humans

Image Credit: NPS Photo / Rachel Ames

Cody Sanders dives into the world of the birds and finds that resentment is not just beak deep.

Cody Sanders dives into the world of the birds and finds that resentment is not just beak deep.

Throughout history, and even in ancient mythology, crows have been considered highly intelligent creatures. This has led many scientists to wonder exactly how much crows remember and recognise about humans and if they share this information with other members of their species. As shown through different research studies, crows, along with other species of birds, remember the faces of humans. Not only do the birds remember the face of the person, they can recognise it when the person is in different clothes and inform other birds that the person is dangerous and to be avoided.

In one study conducted by Cornell, Heather N., et al in 2011, the researchers found that crows remember the faces of humans who captured the crows. The study was conducted using human face like masks that the researchers would wear when capturing the crows for the study. Through the course of capturing, banding and releasing the bird the captors would wear the same mask so as to insure consistency when working with the crows. The method included using a net launcher to capture the crow, the researcher would then hold the crow for between 10-15 minutes to band and document the bird and then the researcher would release the bird. While the crow was being banded the study noted that other crows would circle in the air around the researcher and offer alarm vocalizations. After the banding and release of the crows the researchers later would walk a 2-3.8km route while randomly wearing one of the masks, including the one that the captor wore, each time they walked the route. Not only would the captured bird remember the face of their abductor, they would inform other birds who would then join in to taunt and dive-bomb that person.

The findings of the study highlight the crow’s abilities to both memorise and identify the mask their captor wore even over a long period of time. Not only that, but the crows also demonstrated an ability to communicate this information to other crows who would then join in on the taunting and dive-bombing of the researchers as they walked along their path. This suggests that the captured crow shared the information that whoever was wearing that specific mask when they were captured was a dangerous human. As such, the other birds responded in turn to attempt to stop the human wearing the mask from coming near.

In a continuation of this same project, the researchers would then show captured crows pictures of random people including the bird’s captor to see how their brain reacted to the images. ‘To see what was going on in the birds' brains when they saw both faces, the researchers injected a glucose fluid into the bodies of fully alert crows. The crows were then put in the presence of someone wearing either the threatening or caring mask for about 15 minutes before the birds were sedated and given a brain scan.’

A lead researcher John Marzluff, of the University of Washington, said in a statement from the school, “The regions of the crow brain that work together are not unlike those that work together in mammals, including humans...These regions were suspected to [react similarly] in birds but [this has not been] documented until now.” This lends strong evidence that crows remember faces and respond accordingly, but what about other types of birds?

Other similar studies have also been conducted with different species of birds including magpies, pigeons and mockingbirds who have all demonstrated similar levels of human face memorization and recognition. Notably, feral pigeons proved to have the best facial recognition skills among wild birds and they did not require any kind of additional training in response to the testing. In a public park in Paris city centre two researchers wore different colour lab coats, one researcher would casually feed the pigeons while the other would actively chase the pigeons away whenever they got near. Sometime later, the researchers exchanged their lab coats for one of a different colour and continued feeding or chasing the pigeons. “The experiment, which was repeated several times, showed that pigeons were able to recognise the individuals and continued to avoid the researcher who had chased them away even when they no longer did so.”

“It is very likely that the pigeons recognised the researchers by their faces, since the individuals were both female and of a similar age, build and skin colour,” says Dr. Dalila Bovet a co-author of this work from the University of Paris Ouest Nanterre La Défense. “Interestingly, the pigeons, without training, spontaneously used the most relevant characteristics of the individuals (probably facial traits), instead of the lab coats that covered 90% of the body.”

In a continuation of this project the scientists say that “future work will focus on identifying whether pigeons learn that humans often change clothes and so use more stable characteristics for recognition, or if there is a genetic basis for this ability, linked to domestication or to having evolved in an urban environment.”

Similarly in yet another study, magpies demonstrated aggressive responses towards researchers who messed with their nests again despite changing their clothing. Researchers would wear different clothes and be lifted up to magpie nests with half the researchers who would touch the birds’ nests and the other half would simply look at it. In response, the magpies would take notice and remember the faces of the select researchers who disturbed their nests. “These results suggest that wild magpies can distinguish individual humans that pose a threat to their nests from humans that have not behaved in a threatening way. The magpie is only the third avian species, along with crows and mockingbirds, in which recognition of individual humans has been documented in the wild.”

Just like the studies involving crows and pigeons, magpies also share the ability to share information about dangerous humans with other birds of their species. This highlights the horizontal learning of birds, within their own species, as they exchange important information especially in relation to specific humans and their recognition of faces.

These three studies highlight the brain power and abilities of birds, including how they learn from each other. Scientists have shown that being aggressive to these kinds of birds lends to aggressive behaviour in return, it appears that birds also follow the golden rule.