Owls should be able to rotate their heads a full 360 degrees, according to an analysis of the birds’ skeletons and muscles – but some researchers still have their doubts.
It has long been known that owls have extremely mobile necks. The birds have been recorded turning their heads entirely upside down, for instance, or rotating them through 270 degrees while keeping their bodies stationary. But Aleksandra Panyutina at Tel Aviv University in Israel and her colleague Alexander Kuznetsov, an independent researcher, suspect an owl’s neck is more flexible still.
The two researchers obtained the bodies of deceased eight owls – belonging to a total of five different species – from two academic institutes in Russia. They then took CT scans of each bird as they rotated its head.
This revealed that owls rely on two strategies during a head turn. First, they rotate some of the joints between the bones in their neck, which allows them to turn their heads up to 126 degrees. Secondly, they physically twist their spine, giving it a spiral staircase-like appearance. Although this coiling severely contorts the spine, Panyutina and Kuznetsov discovered the motion doesn’t damage the bones, ligaments or muscles in the owl’s neck – even if the head turns in a full circle.
As such, Panyutina is confident that “live owls can perform a 360-degree turn”.
Michael Habib at the Natural History Museum of Los Angeles County, who has researched some of the adaptations that allow owls to perform extreme head turns, says the new study is “very cool”. But he doesn’t think we will ever see an owl’s head rotate completely around.
“They were asking whether there’s anything in the bone and muscle that would necessarily prevent a 360-degree turn, and they found that the answer is, somewhat surprisingly, no,” says Habib. But he thinks other anatomical features will probably forbid such turns. Critically, Habib says, the nerves running up the neck would be damaged during a 360-degree spin, potentially leaving an owl unable to fly for several days while the nerves healed. “Nerves don’t like being stretched,” he says.
However, Panyutina disagrees this would be a problem, particularly for nerves, such as the vagus nerve, that pass over the top of the neck muscles. Their placement means these nerves wouldn’t stretch as the bones beneath the muscles twisted and contorted. “The vagus runs freely over the muscles and so easily finds a shorter way during extreme turns,” she says.
To settle the matter, researchers may have to perform experiments with living owls. Panyutina proposes training the birds to focus on a specific target, and then placing them on a rotating platform to see whether they can retain focus on the target through a 360-degree turn.