Unlike most birds, jackdaws' eyes have a dark pupil surrounded by a silvery white iris. The researchers said they believe jackdaws are probably sensitive to human eyes because, as in humans, eyes are an important means of communication for them. The hand-raised birds examined in the study may be even better than wild jackdaws at attending to human gaze and responding to the gestures of the people who have raised them.

The findings are particularly notable given that most other species investigated so far, including human beings' closest relatives the chimpanzee and "man's best friend," the dog, are not particularly sensitive to eye orientation and eye gaze, von Bayern said.

Rather, she continued, chimps and dogs seem to rely on other cues such as head or body orientation in determining the looking direction of others and do not appear to appreciate the eyes as the visual organs. The results suggest that birds may deserve more respect for their mental abilities.

"We may have underestimated the psychological realms of birds," von Bayern said. "Jackdaws, amongst many other birds, form pair bonds for life and need to closely coordinate and collaborate with their partner, which requires an efficient way of communicating and sensitivity to their partner's perspective."

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Editor:Yang Jie