Birds have eyes apart

parrot tucks beak under wing (See photo credit at the end of this article.)

Birds have eyes apart. Does that mean they have strabismus?

I was curious, so I did some research on what birds see. I uncovered some interesting facts.

Most articles I found agree that birds have better visual acuity and precision in detail than humans do! They also have the ability to see ultraviolet light, which enables them to see different hues of the colors that humans see. Birds have more types of color recptors than humans. While humans have 3 different color cones in the retina of their eyes, some writers say birds have 4 or 5 different color cones in their retina.

We can only see red, blue, and yellow and blends of these three primary colors. What if there were another color out there that birds could see but we cannot? Imagine the possibilities, with blending of colors! Add to that the hue “overlay” of ultraviolet light. It is thought that birds see colors the human eye can’t comprehend!

Another concept is that an object does not have a color. Color is in the receptors of our eyes and the message our eye gives our brains about the color it sees. We see a red ball as red because our color receptors see red. It is possible that birds see things colored differently than we do.

I remember thinking my mom must have eyes in the back of her head when she would know what I was doing without even turning around to see. But birds really do have eyes in the back of their heads in a sense. Some birds’ eyes are set farther back than others. Those with eyes more toward the back can actually see a 3-d overlap in their vision in the back!

Birds whose eyes are more toward the front of their head have better front 3-d vision. But for the most part, this is where humans excel. Because our eyes are in front of our head, our frontal vision overlaps, producing the 3-dimentional affect of objects that allows us to have depth perception. Birds may be able to see much more clearly and at farther distances than we, and their color spectrum may be gorgeous! But as a general rule, humans have the advantage in binocular vision.

However, binocular vision (depth perception) is usually limited for those of us with strabismus. Strabismus weakens our 3-d (depth) vision because our visual fields can no longer overlap in the front. Birds are often seen bobbing their heads up and down. It is thought that this helps enable them to judge distances. In a similar way, humans with strabismus often develop a head tilt that enables them to see more accurately.

As I studied all this, I could not help but think of how our Creator is able to make colors and patterns and beauty that we humans are not even aware of even when we are right in the middle of it! It almost seemed that God favored the birds when he created vision, until I was also reminded of a passage from the Christian Bible:

Are not five sparrows sold for a tiny sum of money? Yet God does not forget about one of them.

Even the number of hairs on your head is known. So do not fear. You are worth more than many sparrows.’

This was an interesting study for me, and I hope you enjoyed it also. I’m posting the links below of some of the articles I looked at. You’ll find a lot more cool stuff and diagrams of how birds see in the articles!

In addition, I’ve chosen the photo used in this item as a featured photo!

References:
Sense of Vision for Birds
Exploring the Fourth Dimension
British Garden Birds
Bird Eyes
The marvelous avian eye
Luke 12:6-7 WE translation
Photo credit: ‘Shy Parrot’ by Rudo Havo

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