Why are Crows Left or Right Beaked When Wielding Tools?

"Binocular vision is often connected to allowing the brain to compare the images seen by each eye, inferring properties of the scene from the differences between these images," explains Antone Martinho of the University of Oxford. "We thought that their binocular fields would facilitate binocular vision, perhaps allowing the birds to judge the distance from tool tip to target. It turned out that, most frequently, they only see the tool tip and target with one eye at a time."

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In other words, the birds are using their notable binocular vision for better monocular vision, allowing each eye to see further toward the other side of the beak. The birds' unusually wide binocular field is among the first known examples of a physical adaptation to enable tool use, the researchers say.

The crows are one of the most innovative tool users in the animal kingdom, and for good reason. They must use sticks to extract larvae from burrows. In some ways, the New Caledonian crows have a tougher problem to solve than humans do when it comes to using tools, because they don't have the luxury of moving their eyes and beaks independently like humans can with their eyes and hands.

Nevertheless, the findings are a reminder of our shared animal natures, the researchers say.

"Birds and humans face similar problems in tool use and many other activities," Kacelnik says. "Studying similar problems across species helps to put all of them in perspective."



Source: Eurekalert