The Fascinating Eyesight of Birds

Birds have a great view of the world, but that's not just because they get to soar above it. Our feathered friends have truly amazing eyesight. In fact, the clarity with which they see the world is similar to that of humans. But birds actually process the information they see much faster than humans and they can spot movement much better.

A bird's eyes may seem tiny, but there is actually much more to their eyes than what is visible to us outside of the bird's head. Part of the eye is hidden by the bird's eyelid and skull. The eye is one of the largest parts of a bird's head and can sometimes even weigh more than the bird's brain. According to www.birdnote.org. the bird's eyes account for about 15 percent of their head's weight. In contrast, a human's eyes account for only about 1 percent of our head's weight.

The eyesight of birds also varies considerably among the many species of birds. Their eyesight is practically customized for their own individual needs. All birds have the fascinating ability to see in what is termed binocular and monocular vision. This simply means birds eyes work together as a pair to see straight ahead, but each eye can also see independently of the other eye. This monocular vision is the reason for the varying placement of the eyes on different bird species.

For instance, the pigeon has eyes on the side of its head. This placement gives them the amazing capability of seeing almost everywhere around them. The only place they can't see is directly behind them. The American woodcock's eyes are situated closer to the top of the head and can therefore see what's behind it! This bird can still see what is in front and above the head as well.

Other types of birds that catch fish will sometimes have eyes set lower on the head to better enable them to see what's below them. This helps the fishers to skim the water and see their prey in the water below.

Birds do lack the ability to roll their eyes in the eye socket the way humans can. This indicates the bird must turn their heads to see in another direction. It's common to watch an American robin cock it's head to one side. It appears to be listening to something. After all, we're accustomed to seeing dogs do this movement. In reality, this frequent backyard visitor is turning its head to spot the worm on the ground.

Of course the eagle is renowned for it's amazing vision and the bald eagle is no exception. It has astounding capabilities with its eyes. An eagle's eye is almost as large as a human eye, but with vision that is four times sharper than a human with perfect vision. According to www.baldeagleinfo.com, the bald eagle has two centers of focus known as foveae. This majestic bird can see both forward and to the side at the same time and actually focus on both places! This website also states, "The eagle can probably identify a rabbit moving almost a mile away. That means that an eagle flying at an altitude of 1000 feet over open country could spot prey over an area of almost three square miles from a fixed position."

As if all of these vision capabilities aren't enough, birds also see in color. It's believed by scientists that birds see color in much the same way as humans but a bird's retina is more complex than ours. They have a special area in the retina which contain colored droplets of oil. The quantity of oil, the location and the color of the droplets of oil vary from species to species.

This indicates that even the color vision for birds is practically customized for their individual needs. For example, a kingfisher has more oil droplets than most birds. It's thought to help the kingfisher block some of the glare from the water as they are fishing for food. A pigeon has brighter drops of yellow oil in the bottom portion of their retina. Scientists believe this might help to dull the brightness of the blue sky during flight.

A bird's eye view can take on new meaning when we realize just how complicated their vision really is. It's easy to understand how the slightest movement from a window while watching birds feed nearby can cause a quick departure. They can spot the slightest movement when we think we're being unobtrusive. Bird watchers will still keep spying and birds will still spot us. After all, they do have the advantage of a bird's eye view.