Even if birds have their eyes on the side or at the front, they have the ability to see straight. However, there are many added benefits for the birds, due to its eye placement.
So, let’s dive deep into the facts about how birds see the world with eyes on the side of their head.
How Does the Position of Bird’s Eye Affect Their View?
With two eyes, one can see three-dimensional images around them, which helps them to perceive the height, width, and depth of an object. The position of the bird’s eyes on its head affects the field of vision. If the eyes are at the front, then they have a smaller field of vision, approx 150 degrees, whereas the birds that have eyes on the side have a much bigger field, approx 300 degrees, such as parrots, and pigeons.
Birds have special visual receptors which help them to detect the colors and being larger in number than humans, cone cells help them to discern colors better. They can also distinguish fine details and that too from a distance. Some species of birds, such as eagles and hawks, also have the ability to perceive UV light which helps them to locate prey.
However, birds are clever creatures and to compensate for their limitation in binocular vision, they tend to engage in different behaviors which help them to optimize their visual capabilities, such as head and eye movement. While they are migrating, they can perceive polarized light, in optimal lighting conditions which helps them to navigate through the correct path.
How Birds with Eyes on the Side are Benefited?
The birds with eyes on the side can see in the front and at the same time a long way to the side. This acts as a huge advantage as they have very small blind spots, so they can see their path as well as keep eyes on the predators who might try to sneak in from the side.
Comparatively birds with eyes on the side of the head can see more than the ones whose eyes are placed forward. This is an evolutionary adaptation that birds go through so that they can scan their surroundings easily.
When a bird’s eyes are present on the side of the head, it is known as lateral positioning and they can approach a prey or spot predator without the need for turning the head. Some birds also can rotate their head, which helps to provide a 360-degree or panoramic view of the surroundings.
However, there is one disadvantage, since the eyes are placed sideways, they have difficulty perceiving the depth. Also, their binocular field of vision gets narrowed, which often affects their ability to judge the distance accurately.
What is the Structure of Bird’s Eye?
Bird’s eyes are adapted to help them to fly, navigate, and hunt. Based on specific needs, their visual system has evolved. Here’s how the bird’s view differs from others:
- Birds have large bulbous eyes which are present on the side of the head, helping them to get a wider view.
- Some birds have rounded eyes while others have elongated tubular eyes which help them to see at a distance.
- Birds have rod and cone cells which help in adjusting to various light intensities.
- By controlling the size of the pupil and shape of the lens, birds can adapt to different environments.
- Some birds are also seen to have multiple fovea, which is an area at the center of the retina and it helps in perceiving high acuity and color vision.
- Some birds have binocular vision while others have monocular vision.
What is Binocular Vision?
Birds have the ability to see a wider field and can also focus better than humans, which is called binocular vision. This ability has been developed due to stereoscopic vision, where the bird uses both eyes simultaneously to get a better perception of depth and to detect an object accurately. This adaptation has helped the birds to navigate through morphologically complex environments and also stay protected from predators or spot prey.
What is Monocular Vision?
Monocular vision is an adaptability in a bird that helps them to see their surroundings with each eye separately without getting overlapped. They are capable of judging the distances accurately as they get to analyze multiple perspectives simultaneously. They are even able to spot UV light patterns and get a panoramic view. The birds have a higher number of photoreceptors and also can detect objects at a greater distance due to larger visual fields. They also get to discriminate against the colors due to the presence of a highly sensitive retina. Based on their food acquiring techniques the monocular vision is further adapted to unique abilities.
How Do Birds Judge Distance?
Birds judge the distance, size, and position of an object through relative comparison with another. They determine the amount of light and shade on objects and also use motion parallax, which is the apparent movement of objects when the bird moves its head.
What is the Difference Between a Bird Eye and a Human Eye?
Significant differences can be seen between a bird’s eye and a human eye. When the sizes are compared, bird’s eyes are relatively larger and they also have the ability to detect light intensity due to the presence of many receptor cells. On the other hand, human eyes are relatively smaller with lower numbers of receptor cells. Birds have 4 cone cells whereas humans have 3.
