Hawk’s eyes nearly the size of a human’s

By | January 13, 2017

If you’re looking for something new for your family to do during lengthy car trips this winter, try this: Ask each family member to guess the number of hawks that’ll be seen between the point of departure and your destination.

Besides keeping young minds occupied as they look for hawks in the trees along the road, it’s also a good way to give a little extra attention to a common, yet interesting, area bird.

Seeing red-tailed hawks on roadsides in winter is nothing unusual, but it’s still a head-turning event for most people.

Part of the reason is size; it’s hard to miss these large (up to 25 inches in length and three pounds in weight) birds and their buff-colored breasts.

For those who take closer looks through binoculars or camera lenses, a red-tailed hawk’s fierce look adds to its appeal. Then, of course, there’s that defiant scream which is a well-known wildlife sound.

Although red-tailed hawks are highly efficient predators, they aren’t the big farm pests they are often portrayed to be. Red-tailed hawks take a greater variety of prey than any other American raptor except the golden eagle, but much of a hawk’s diet consists of creatures other than poultry.

Between 70 and 85 percent of a red-tailed hawk’s diet are mice, rats, moles, squirrels, rabbits and other small mammals. A variety of birds make up 10 to 15 percent of a red-tailed hawk’s diet. During warmer months, reptiles, frogs and insects are included on a hawk’s menu, too.

One of the remarkable characteristics of a red-tailed hawk is its vision. The term “eyes like a hawk” is more than just an old saying. Even though a hawk’s head is much smaller than ours, its eyes are nearly the same size as a human’s.

This size results in a larger image cast upon the retina. The area of critical focus in the back of a hawk’s eye, known as the fovea, has many more visual cells (called cones) than the same area of a human eye.

A hawk’s eye has two foveas in the retina; humans have only one fovea. With all these visual tools, it’s little wonder that a hawk’s vision is estimated to be eight times better than a human’s.

Like many other raptors, hawks get what appears to be a “fierce” expression from a bony shield that projects above each eye. Besides shading their eyes from the sun, this also protects the eyes from brush and other vegetation when the hawks are in pursuit of dodging, feinting prey.

If you ever wondered why you see so many hawks along roads, look at the surrounding area. The brushy edges and adjoining fields along many of our roads are home to many of the small mammals upon which hawks like to feed.

Hawks can be found in Missouri throughout the year, but a lack of foliage in winter makes these birds more visible. It should be remembered that hawks are federally protected birds and cannot be shot or hunted.

Of course, red-tailed hawks aren’t the only species of hawk found in Missouri. Cooper’s hawks, sharp-shinned hawks, kestrels, northern harriers and red-shouldered hawks are among the other types of hawks seen in the state.

By Francis Skalicky

(Francis Skalicky works for the Missouri Department of Conservation in southwest Missouri. He can be reached at 417-895-6880.)

tel:18003947179

Leave a Reply

Your email address will not be published. Required fields are marked *