The Eye of an Eagle

BY AWAKE! WRITER IN SPAIN

SPANIARDS describe a sharp-sighted man as having the eyesight of an eagle (vista de águila). Germans have a similar expression (Adlerauge). Not without reason, the eagle’s keen eyesight has been proverbial for centuries. The book of Job, written over three thousand years ago, says of the eagle: “Far into the distance its eyes keep looking.”​—Job 39:27, 29.

How far into the distance can an eagle actually see? “Under ideal conditions a golden eagle (Aquila chrysaetos) can detect the slight movements of a rabbit from more than [1 1⁄4 miles] [2 km] away,” explains The Guinness Book of Animal Records. Others have estimated that the eagle can see even farther!

What gives the eagle such acute vision? First of all, the golden eagle has two huge eyes, which occupy a large portion of the head. The Book of British Birds notes that in the case of the golden eagle, its eyes “are, in fact, as large as they could be without becoming so heavy as to impair flight.”

Furthermore, an eagle’s eye has approximately five times the number of light-receptor cells that we have​—some 1,000,000 cones per square millimeter compared to our 200,000. Practically each receptor is connected to a neuron. As a result, the eagle’s optic nerve, which carries messages from the eye to the brain, contains double the number of fibers found in that of a human. Little wonder that these creatures have keen color perception! Finally, birds of prey, like other birds, have eyes equipped with a powerful lens that can change its focus quickly from objects an inch away [a few centimeters away] to those at a great distance. Their eyes far outmatch ours in this respect as well.

The eagle’s vision excels during broad daylight, but at night the owls have the advantage. These nocturnal raptors have eyes with abundant light-sensitive rods and a large lens surface. As a result, they can see 100 times better at night than we can. On those rare occasions when there is total darkness, however, owls must depend exclusively on their acute hearing to locate prey.

Who gave these birds such attributes? God asked Job: “Is it at your order that an eagle flies upward?” Obviously, no man can claim credit for this marvel of creation. Job himself humbly admitted: “I have come to know that you [Jehovah] are able to do all things.” (Job 39:27; 42:1, 2) The eye of the eagle is just one more testimony to the wisdom of our Creator.

[Picture on page 24]

Golden eagle

[Picture on page 24]

Snowy owl