Great Horned Owl (Bubo virginianus)
The eyes of an owl constitute a remarkable 1% to 5% of it's body weight. Proportionately, if humans had eyes like an owl, a 175 pound man would have 9 pound-baseball sized eyes. The enormous eyes are held in place and stabilized by a bony “sclerotic ring”. The ring supports the massive eyes and prevents them from rolling or moving side to side and up and down. To compensate for restricted eye movement, an owl must rotate its entire head to achieve all peripheral viewing. AN OWL CANNOT MOVE ITS EYES WITHOUT MOVING ITS ENTIRE HEAD. An owl has several anatomical features that accommodate 270 degree right and left head turns. Considering that 360 degrees is a full circle and 180 degrees is half a circle, an owl can rotate its head much more than halfway around (270 degrees). Owls have twice the number of cervical vertebrae as that of humans; more vertebrae mean increased flexibility. Additionally, owls possess specialized musculature and enlarged foramina and bone canals that allow blood vessel “slack” so that veins, arteries and nerves aren’t damaged or restricted during head rotation. Imagine, if the veins and nerves were bound in sheaths and more fixed within the neck; extreme head rotations could occlude blood flow to the brain and damage neurovascular structures.
Great Horned Owl, (Bubo virginianus) translates to “the Virginia owl”. Bubo is Latin for owl and virginianus is Latin referring to Virginia the location where the owl was first observed and documented. Although similar to the Eurasian Eagle Owl (Bubo bubo), the Great Horned Owl is a separate species and inhabits North and South America only. The horns are feather tufts that may function as camouflage and possibly act as communication devices.