Walnut Creek Open Space Foundation
Walnut Creek Open Space Foundation |
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| Have you ever noticed how
eyes are set onto animals in different ways? The chicken sees out from only
one side of his head and therefore has to turn its head once in a while
since it can see one only thing with a single eye. Predators, however, have
eyes in the fronts of their head so they may see their prey more easily
with binocular vision. The visual acuity of hawks is regarded as being some
twenty times better than human vision. To test this, stand on top of Shell
Ridge and watch the White-Throated Swifts zoom by at over thirty miles per
hour. They are not randomly flying around gobbling up tiny insects that happen
to be in their way—they can actually see them approaching on the wind and
these birds adjust their flight pattern to intercept them. Owls have larger eyes for their heads than most other predators since they require more light-gathering power for their crepuscular (dawn and dusk) and nocturnal (night time) activities. Hawks are diurnal (day time) and soar along looking for movement. They can distinguish such motions where everything around the object stays still. Many birds have pigmentation in their eye that limits the range of colors they can see. This permits then to focus more sharply because the eye doesn’t have to accommodate for chromatic aberration, as does the eye of man. Other birds, such as the black-shouldered kite, hover above an area and then speed down to their prey. Peregrine falcons have been clocked at over 120 miles an hour as they dive—all as a result of their being able to see something that we cannot. During this dive, they never lose sight of their prey. Try this sometime! Many animals that are preyed upon do not have binocular vision, but all predators do. Man, too, has binocular vision. Jerry Fritzke 6/21/03
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The daunting gaze of a female golden eagle in Shell Ridge 
Don Jedlovec © 2002 |