In the movie Casablanca, actor Humphrey Bogart toasts actress Ingrid Bergman with the famous line “Here’s looking at you, kid.” His choice of a verb—looking—implies an immediately important, and lasting connection among humans. When we look at others, they have our attention. Our expressive eyes are among our most important organs of non-verbal communication. The degree to which our eyes are dilated or their lids are blinked indicates our mood. Our gaze may portend our attention to a distant object or intention to move in a certain direction.
Given the importance of eyes to our communication, it seems reasonable for other species to notice and react to them as well. Anyone who lives with a pet or tends domestic stock knows that this expectation is met. Try staring at your dog. She may bark, growl, come forward, or shy away in response. She will not ignore your ogling. Scientists have demonstrated that dogs and sheep even pay attention to where we look—they follow our gaze and search where our eyes suggest that a treat may be hidden. Domestic mammals are not alone in being able to read our eyes. A few wild birds that frequently live among us also take note of our gaze, or at least our head direction, as we approach them. Starlings, house sparrows, and jackdaws become wary when we stare. This attentiveness may enhance their ability to survive and reproduce in our cities, towns, and farmlands.
My colleagues, Dr. Barbara Clucas, David Mackovjac, and Ila Palmquist, in a paper soon to be published in the journal Ethology, tested the abilities of Seattle’s crows to attend to human gaze and expression. These birds are supreme city dwellers. As I’ve discussed before, they recognize our faces and remember our past deeds. But do they pay attention to our eyes? By walking toward crows as they fed on the ground, we either stared at them or averted our gaze (but kept our face pointed toward them). As an indication of the crow’s attention, we measured the distance away from the crow and us when the bird reacted to our presence.
We found that looking at a crow put it on edge. If we approached a crow with our eyes averted to the side, we could get 3 meters closer before the bird scurried off than if we looked directly at the crow. And most of the time a stared upon crow flew, rather than walked, away. It did not matter if we smiled or frowned as we walked crowward. It was our eyes, not our mouth that the crows seemed fixed upon.
What does the crow’s attention reveal about its intelligence? Clearly, wild crows keep a careful eye on the people that pass them by, and they ascertain what our intentions may be from our subtle behaviors and hurried glances. They may even know what we are thinking. More likely, they are simply reacting to social cues that they use amongst themselves or perhaps remembering past associations they have learned between a person’s gaze and their subsequent action. Both of these latter ideas may in part be true.
A stare is a prehistoric signal of threat. Iguanas perceive stares as threats. Aggressive and fearful birds stare more and blink less at their flock mates than do passive birds. More collegial behaviors follow rapid blinking, not staring. So crows may be adapting their natural understanding of a fixed gaze to their new, urban world. By watching our eyes, crows can gauge their reactions to a likely threat. And in so doing, use an ancient understanding to guide their modern lives. As we reinforce our signal with action—harassing birds we glower upon, for example—long-lived animals like crows also come to strengthen the connection. They update their basic understanding of a stare to include that of a new species. Here’s to looking at you, crow.