Jackdaw's piercing stare warns off competitors, study shows

Jackdaw's piercing stare warns off competitors, study shows

A new study shows that Jackdaws use their eyes to communicate with each other, marking the first time this behavior has been documented in non-primate animals.

The Jackdaw is an omnivorous crow-like bird with a piercing gaze due to its unusual pale-colored irises.

“Jackdaw eyes are very unusual,” lead study author Gabrielle Davidson said in a statement. “Unlike their close relatives, the rooks and crows – which are very dark eyed – jackdaw eyes are almost white and their striking pale irises are very conspicuous against their dark feathers.”

Indeed, most birds have very dark-colored eyes, with only 10 percent of perching birds possessing irises of any color at all.

The researchers found that the jackdaws use their eyes as a warning to protect their nests from competitors.

“Before now we knew very little about why some birds have brightly colored eyes,” Davidson said.

Jackdaws nest in tree hollows, and because the tree hollows are naturally-occurring and not crafted, the Jackdaws have to compete for the limited number of them. Davidson explains that because the Jackdaws nest so closely together, they end up fighting over the nesting locations.

“In jackdaws, the pale eyes may function to improve their ability to defend their nest and chicks from competitors. It also raises the question of whether this is unique to jackdaws, or if other cavity nesting birds also use their eyes in a similar way.”

Davidson made the discovery by analyzing video footage captured in 100 different Jackdaw nest boxes. She installed one of four different photos in the nest boxes– each photo with a variation of the Jackdaw eye colors to observe the difference in behavior that occurred when Jackdaws approached the nests. She found that the photos which contained the brightly-colored Jackdaw eyes detered birds from landing on the nesting spot.

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