|"Yellow-eyed Hawk" Colored Pencil|
Finding your place in the world today can be a challenge but this bird of prey is more than well-equipped to thrive in the wild. An eastern red-tailed hawk stares confidently out of a blazing, autumn background. After two years of age, the extraordinary yellow eyes of this juvenile will transform into a dark brown.
Raptor vision has evolved to become the sharpest in the Animal Kingdom. The visual acuity of the hawk is legendary. Using its excellent eyesight to find and capture its prey, a red-tail can spot a rabbit from two miles away. Large eyes allow for maximum levels of light so the retinal picture is composed from a greater number of optical cells resulting in a higher resolution image.
The hawk has front facing eyes that give it binocular vision which is assisted by a double fovea. With binocular vision, the fields of view of the left and right eye overlap. This binocularity allows for stereoscopic vision, which in turn provides for spectacular long distance perception.
A fovea is a small area of acute vision in the retina where the concentration of visual cells is the most intense. We have one fovea while a hawk, with its wide binocular field of view, has both a central and lateral fovea. That's one reason why a hawk can see eight times more clearly than even the sharpest human eye.
The hawk's adaptations for intensified visual resolution has come at a cost though. The huge eyes occupy a substantial portion of the skull allowing only limited room for the brain. Also, it has a poor range of view in low light levels so the bird must roost at night.
My impression of the red-tailed hawk is that despite those limitations, the tradeoff appears to have worked out just fine. As you can plainly see, the future for the young raptor pictured above certainly appears to be bright.