March 31, 2013 - Owl Festival - Part 2
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The photography session I attended at the International Festival of Owls gave me a chance to take some photos that show interesting things about owls. This is a close-up of a Barred Owl. Note that even its eyelids are covered with feathers. I’ve asked several experts about this, and, while some other bird species also have feathers on their eyelids, owls seem to have more of them. Two possible reasons for this are keeping the eyes warm in cold weather and protecting the eyes when crashing into prey at night.
Most owl photos show their heads facing forward, like the photo on the right. The side view of this Barred Owl shows how the feathers on its face form a disc, kind of like a satellite dish. That helps funnel sounds into their ears, which are located within the facial disc. Also note how long the head looks from front to back. It’s not really that large, of course, because an owl’s feathers are very “puffy” and make the head look much bigger than it really is.
The shape of an owl’s eye is tubular, not round like ours, so the eye cannot be turned in its socket. This means the owl must turn its whole head in order to see to the side. The amazing thing is that an owl can turn its head 270 degrees in either direction. That means the owl could look to the left by turning its head to the right, rotating the head three-fourths of the way around. They don’t usually do that, of course, but this photo shows a Barred Owl turning its head 180 degrees to look behind it. One reason owls can do this, and we can’t, is that they have 14 vertebrae in their necks and we have only seven. This gives them a lot more flexibility.
Owls, as well as many other bird species and some mammals, have a second eyelid called a nictating membrane. It moves side to side, from the inside corner of the eye to the outside. It has moved about halfway across the right eye of this Great Horned Owl and is just starting to be visible in the left eye.
The nictating membrane of this Barred Owl appears to be blue but I think that is just the angle of the light in this photo. The nictating membrane is not totally clear, but does need to be translucent so the owl can see through it. Closing the membrane allows the owl to moisten its eye without losing sight of whatever it is watching. The membrane can be closed when the owl is hunting at night, protecting the eye from being scratched either by a branch or by prey. That obviously means the owl has to be able to see through it.
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