"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.