Humans use their eyes apart from speaking for communication. Even a toddler can understand what his parents’ intent to signal him (anger, love, happiness) through their eyes. But how far animals are capable of conveying their feeling to other members of the clan through eyes, is not deeply studied.
For the first time, researchers from Cambridge and Exeter have discovered that non primates are capable of using their eyes as an alternate means of communication. They have seen jackdaws communicating with another member of the species using their eyes. In order to ward off competitors approaching to their nest boxes, jackdaws show warning signs using eyes.
Researcher Gabrielle Davidson from University of Cambridge says that the jackdaw’s eyes are very conspicuous against their dark plumage. Their eyes are white with pale irises stand apart from its nearest relatives, such as rooks, crows and raven, who have black or dark brown colored eyes. Bright eyes are not uncommon in the bird’s world and 10 percent of perching birds are known to have colored irises. But the question whether jackdaw uses their bright eyes to convey message to other jackdaws was not known.
Gabrielle explains that the jackdaws unlike other most birds do not make nests in the tree branches rather chooses naturally occurring cavities of the tree trunk as a nesting site. Moreover they could not excavate cavities like woodpecker does and so often has to compete with other jackdaws for the best nesting spot. And generally what start these fights are jackdaws advancing nest boxes that are not their personal.
For the research Davidson used one of the four different images which were placed in 100 jackdaw nest boxes situated on the outskirts of Cambridge, just before the arrival of the breeding season. The images were a pair of jackdaw eyes, either black (the control), jackdaws eyes on a jackdaw’s face and a jackdaw’s face with black rook eyes. The reactions that the images had on the bird’s behaviour were recorded.
Almost 40 recording of jackdaws peeping into nest boxes were analysed. They revealed that the box which had images of a jackdaw with its bright eyes were the one which warded off peeping birds from occupying them than with the nest boxes with other three images. The birds avoided spending much time close to such a nest box. Therefor the study for the first time support that even a non primate such as jackdaws uses eyes to communicate with other members of the same species.
Until now we were not sure of what role, such bright eyes in bird’s plays. In jackdaws bright eyes have a vital function and are not just pretty feature. Imagine jackdaw staring straight at the intruder while sitting in the black cavity in the tree, signalling the intruder that the place has been already taken and avoiding any fight in the first place. But whether other birds staying in the tree cavity uses eye to convey their intentions in a similar way is still to be discovered.