Solving the Mystery of Owls’ Head-Turning Abilities

Squeaky the Squirrel

Using medical illustations, CT scans and angiography, which produces X-ray images of the inside of blood vessels, researchers studied the bone structure and vascular structure in the heads and necks of a dozen snowy, barred and great horned owls after their deaths from natural causes.

When researchers injected dye into the owls’ arteries to mimic blood flow and then manually turned the birds’ heads, they saw mechanisms at play that contrasted greatly with humans’ head-turning ability. Blood vessels at the base of the owls’ heads, just below the jawbone, kept expanding as more of the dye flowed in. Eventually, the fluid pooled into tiny reservoirs. Our arteries tend to get smaller during head rotations and don’t balloon in the same way.

But these silent hunters’ head-on-a-swivel ability continued to be more complex, researchers found. In owls’ necks, one of the major arteries feeding the brain passes through bony holes in the birds’ vertebrae. These hollow cavities, known as the transverse foraminae, were ten times bigger in diameter than the artery passing through it. The researchers say the roomy extra space creates multiple air pockets that cushion the artery and allow it to travel safely during twisting motions.

http://news.discovery.com/animals/pets/how-owls-spin-heads-around-130201.htm
http://blogs.smithsonianmag.com/science/2013/02/solving-the-mystery-of-owls-head-turning-abilities/
http://www.dailymail.co.uk/sciencetech/article-2271514/How-owls-turn-heads-Scientists-uncover-secrets.html