Researchers from the Seoul National University found that wild birds appear to "think faster" when humans, and possibly predators in general, are directly looking at them.
"We started this study from our experience" says Dr. Sang-im Lee, the leader of magpie research team and the first author of the paper. "For a long time we had this impression that somehow magpies know that we are watching them because they often fly away from us when we observe them. But when we don't observe them, we can pass them pretty close-by but they don't fly away!"
The finding that animals notice the gaze of humans is not new. Usually animals use gaze of the conspecifics in social contexts and therefore pet animals pay attention to the gaze of humans – their social mates. Also in the case of predator and prey interactions it is well known that animals such like birds, lizards or deer move away or escape from humans at larger distances when people look directly at them. In these situations it was believed that animals react at larger distance and sooner because the gaze is an indicator to the prey that the predator "wants to catch it". Therefore, when a prey notices the gaze of a predator it moves away from the predator in order to increase safety. Not suprisingly, the researchers found that magpies on the campus of the Seoul National University also flew away at larger distances when humans were directly looking at them.
But this is not the most important finding of this research. When researchers, who were approaching foraging magpies, looked directly at the magpies, the magpies took the decisions faster regardless of whether the final decision was to return to foraging or to fly away and whether the stress or danger perceived by a magpie was low or high. But when the approaching pair of humans did not look at the magpies, the decision to escape or not was taken with a delay. In other words even if the magpies did not perceive the humans as dangerous they still took the decision faster (in this case decision to stay and continue foraging) when the humans were looking at them. This is consistent with the idea that the birds are able to extract more information for their quick decisions from people's faces and/or gaze direction regardless of what kind of information they get. Magpies have lived near humans for centuries or even millenia and such skills might have been important for their survival.
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More information: Lee SI, Hwang SY, Joe YE, Cha HK, Joo GH, Lee HJ, Kim JW, and Jablonski PG.2013. Direct Look from a Predator Shortens the Risk-assessment Time by Prey" PLOS ONE ; dx.plos.org/10.1371/journal.pone.0064977