Make a cardboard cut-out of a one inch long fish. Place it upright on top of a post. Now start backing away from it until you can't see it anymore. Stop and move forward until you can see again. Try to find that exact place and mark it. This place marks the limit of your eyes' resolving power. Next, measure the distance from the fish to where you marked your limit. Now multiply that distance by 8. The answer will be how far away a Bald Eagle could see the same fish.

Now imagine that fish was the size an eagle would swoop down and catch. Let's say one foot. Since there are 12 inches in a foot, the distance you would be able to see that object is 12 times greater than the distance you saw the 1 inch object. So if you want to know the distance at which an eagle could see a fish that is one foot long, multiply the number you got in the previous problem by 12. Example:

1 inch object.

I can see the object 99 feet away

A Bald Eagle can see the same 1 inch object at 99 X 8 = 792 feet away.

If the object were 1 foot long (or 12 times bigger), the eagle would be able to see from a distance 12 times greater or 12 X 792 = 9504 feet.

If there are 5280 feet in 1 mile, we divide 9504 by 5280 = 1.8 miles!

An eagle's sight is different than humans' in another way. Eagles cannot move their eyes in their sockets like we can. To compensate for this, eagles have a very flexible necks. Their eyes have a much narrower forward field of vision. This is also a big plus because when they attack their prey at high speeds; they can quickly adjust their focus and depth perception to avoid crashing into something. If we traveled at speeds equal to that of a Bald Eagle, we would probably smash into a tree because our eyes wouldn't adjust quickly enough.

 

 

Although sight is the eagle's most important sense, it also has a good sense of hearing. However, they rarely use hearing to locate prey. So what do they use their good hearing for? Eagles use their hearing to communicate with other eagles. Eagles need to communicate with each other for a variety of reasons. They use calls to attract a mate and connect with their young. In the eagle's world, all the other senses are relatively unimportant. It is believed that they do not have a good sense of smell. Eagles are often seen feeding on carrion and other rather smelly animals.

 

The nictitating membrane is a tough, cloudy membrane that protects the eye. The membrane helps to clear and moisten the cornea and is often closed on impact with prey to protect the eye.