Jackdaws Respond to Human Attentional States and Communicative Cues in Different Contexts

Humans communicate their intentions and disposition using their eyes [1, 2], whereas the communicative function of eyes in animals is less clear [3]. Many species show aversive reactions to eyes [4-6], and several species gain information from conspecifics' gaze direction by automatically coorienting with them [7]. However, most species show little sensitivity to more subtle indicators of attention than head orientation [3, 8] and have difficulties using such cues in a cooperative context [9, 10]. Recently, some species have been found responsive to gaze direction in competitive situations [11-13]. We investigated the sensitivity of jackdaws, pair-bonded social corvids that exhibit an analogous eye morphology to humans, to subtle attentional and communicative cues in two contexts and paradigms. In a conflict paradigm, we measured the birds' latency to retrieve food in front of an unfamiliar or familiar human, depending on the state and orientation of their eyes toward food. In a cooperative paradigm, we tested whether the jackdaws used familiar human's attentional or communicative cues to locate hidden food. Jackdaws were sensitive to human attentional states in the conflict situation but only responded to communicative cues in the cooperative situation. These findings may be the result of a natural tendency to attend to conspecifics' eyes or the effect of intense human contact during socialization.