Just as humans can communicate ownership with a hard look -- and what they'd do should that ownership become threatened -- so can birds. Specifically, University of Cambridge's (in England) Gabrielle Davidson and colleagues studied the implications of stare downs between Eurasian jackdaws, a medium sized, blackish-bluish bird belonging to the crow family, National Geographic reported.
Previous research showed that jackdaws, as well as basking black iguanas, jewel fish, house sparrows, and starlings felt fear and usually fled at the sight of eyes, which they associated with predators, according to Nat Geo.
Davidson's project sought to determine if the sparrow-like bird invoked the same sense of fear in other members of its species by its own gaze.
Because jackdaw eyes, like all bird eyes, are located on the sides of its head (and thus better suited for avoiding direct contact with other bird eyes), they don't need to contort their faces to convey aggression like humans; they only need to ensure other jackdaws see them.
Jackdaws were also a convenient research choice because their bright white eyes and dark black pupils are highly distinguished against their dark feathers. Thus, the eyes would be easy to simulate in an experiment, which the researchers did by constructing four pictures: a depiction of a jackdaw face with white eyes; a face with black eyes; a large, open white eye; and a large, closed black eye.
After setting up birdhouses attractive to jackdaws, experimenters displayed the various pictures at different times and observed behavior. They found that the picture of a jackdaw with open eyes was the greatest deterrent, indicating that jackdaws perceived open eye contact from members of their own species in the same way they perceived it (and perhaps even more strongly so) in predators: as a sign of territory and aggression that could lead to physical confrontation.
