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Surprise! Nothing to See Here Today

“Here’s Looking at You!”: The Amazing Eyes of Birds

By Diane Darrow

As a big-city dweller, I often like to sit on a bench in my local community garden appreciating nature – the clean, fragrant air; the trees, plants, and flowers; and the many visitors that pass by on the paths and lawn.

I particularly enjoy looking at the avian visitors because the garden attracts many kinds of birds.

One day I was struck by the differences in eyes between people and birds. People have basically almond-shaped eyes, with a colored circle, the iris, in the center and whites tapering to the ends.

Most of the birds I see – such as sparrows, robins, blue jays, and doves – have tiny, round, all-black “boot-button” eyes. I wondered about that difference, so I did a bit of research.

Boy, did I learn a lot! For one thing, it seems that birds actually have very big eyes. They do have whites, but in most species, we can’t see them: Everything but the iris is covered by feathers. And birds’ eyeballs are huge in proportion to the size of their heads. If human eyes were in the same proportion, our eyes would be as big as tennis balls.

Next, birds’ eyes are positioned on their heads differently from the way ours are. Human eyes are set forward on the face, so we can see straight ahead with 3-D binocular vision. That’s true of only a few bird species (owls, for instance.)

Most birds have eyes that angle out to the sides of their heads, so their brains have to reconcile two separate, overlapping fields of vision to see what’s directly in front of them. Oh – so that’s why I often see a robin tilting its head sideways to focus its “good eye” on something on the ground!

Birds’ eyesight is also much sharper than ours. We think we’re doing great if we come close to 20-20 vision. Most birds would score at least 20-10 on our scale. That means, if I’m squinting to see an object lying some distance along a garden path, the blue jay on a branch above my head can see it as clearly as I could if it were only half that far away.

If it’s edible, he’ll grab it.

Moreover, birds’ eyes have at least twice as many light-sensitive cells as human eyes, letting them see much better than us in low light conditions. And beyond the top of our visible color spectrum (red-orange-yellow-green-blue-indigo-violet), birds can see ultraviolet light, which makes colors appear far more brilliant and differentiated.

So now whenever I see plain, dull brown or gray birds in the garden, I try to imagine what they might look like to each other – or what I must look like to them!



Comments

That was a fun read! I had no idea. Thanks.

Yes, this was fun! Just wanted to add my thanks.

Diane, every day I wake to birds singing and while there's been curiosity of them, never have I picked up a book on birds. And of course at the top of their value list must be their eyes. And now I know what they're doing when they bend their heads horizontally. Thank you.

Very interesting! Thanks for sharing. Speaking of doves, I had read that males have blue patches on their necks. I looked and looked and had almost given up on seeing a male dove when one day a dove was sitting on my fence waiting its turn at the feeder when the sun came out at just the right time to illuminate an iridescent sky-blue patches on either side of his neck. I do indeed wonder what we miss in all of nature by not being able to see all of the spectrum of colors.

Diane, this is fascinating! I love watching birds too. But even though I've often wondered about their vision, it had never occurred to me to look it up. So thank you!

I have several bird baths set up in my back yard. From my kitchen window I can watch robins and chickadees and sparrows and nuthatches and even the occasional gorgeous northern flicker splashing around, or drinking from the fountain, or sometimes in really hot weather just sitting there immersed in the water for several minutes at a time, until some other bird comes along and says "get out, it's my turn". It always cracks me up when they do that.

Possibly they're sitting immersed in the water so they'll jostle loose any lice or mites that might be lurking in their feathers. But I prefer to think that, like the rest of us, they're just enjoying the cool water on a hot day.

As happens so often your post today is a delightful in depth piece about a subject I'd never questioned. I knew that hawks and other raptors could see ultraviolet light, and therefore can follow the urine trails rodents leave in their passing. But this broadened my understanding of all birds. And also opens a new line of curiosity for my bird watching. Thank you.

I've always heard that robins tilt their heads because they're listening for worm activity just under the surface. But then they need to see the spot where they're going to poke, so it all works together.

I learned with my own bird, they can get cataracts. That makes me wonder why though.

Thanks, interesting bird news!

Sweet! And did you know a bird knows the difference between if you're looking at it straight into their eyes, or 10 cm beside it. They feel the connection, just as we do!

And all this time, I thought if a bird tilted his head it was "flirting" with me - dang! Great early morning tweet...

Very well Explained! Great work!

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