Jackdaws revealed as first bird species to communicate with their eyes after clever new research from Gabrielle Davidson at Cambridge University. Jackdaws belong to the genus Corvidae along with ravens, rooks, and crows but unique to the group due to their distinctly colored eyes. A white sclera surrounds a colorful iris with a small pupil, very similarly to a humans eyes, but made more vibrant by the dark feather they are centered in. The ability and practice of sending messages with the eyes has long been to thought to only occur in primates and some higher mammals, this is the first evidence of an avian species displaying the behavior. Looking at the Jackdaw, resembling a fancy crow, it is easy to forget they have a nearly the exact same brain to body ratio as humans.
Davidson went about researching whether or not the Jackdaws colourful eyes played a role in how they communicate with each other by setting up dozens of bird houses that simulated the hollows of trees in which Jackdaws make their nest. In each one the team placed a picture that was either black, showed only the outline of Jackdaws eyes, showed an entire Jackdaw face, or a Jackdaw with dark eyes. After reviewing hours of footage from 40 video cameras, it was noted that the birdhouses with the face of a Jackdaw were avoided more than the others, including the Jackdaw with dark eyes. Davidson theorizes that the birds use the attention grabbing properties of their eyes to protect their nests by sending a message to intruders to back off. Although nearly 10 percent of perching birds, or passerines, such as Jackdaws have brightly coloured irises, Jackdaws have been revealed as the first bird species to communicate with their eyes.
Once the research showed the Jackdaws brightly colored eyes were an advantage in protecting nests and offspring from other birds peeking into nests, the intent of the displays was clear. Although the Jackdaw primarily makes its home hollows in tree trunks, it is not able to make the hollows itself, like a woodpecker. For this reason all Jackdaws are constantly competing to find and keep desirable hollows in which to live and raise chicks. The benefit of their brightly coloured eyes is easy to see after watching jackdaws halt their advance into a nest with another Jackdaw staring it down, and even being sure to avoid nests that it knew, or thought it knew, another bird was already occupying.
In mating and territorial control displays the eyes also play a large part, with each bird often staring with intense focus at its rival, sometimes spreading their wings or tails, but always keeping eye contact. Given the similarity to humans eyes, knowing where a Jackdaw is looking is as simple as peeking at where their iris is pointing, allowing the birds an uncanny sense of other creatures are viewing the world around them. In cases where Jackdaws were hand reared, it was not unusual for the birds to look at their caretakers eyes in order to discern what they were looking at. After it was Jackdaws revealed as first bird species to communicate with their eyes, yet another feature of humanity once thought to be unique is taken off the list.
By Daniel O’Brien