Bald Eagle’s Eyesight

Bald Eagle’s Eyesight Related Information:

Birds rely a great deal on their eyesight to mate, to eat, to live, and in all essentially to survive. The sense of vision being so vital to them is a reason why bald eagles have very developed and sharp eyesight, even more so than people in many ways. It is believed that the vision of bald eagles is six times sharper than of humans even though the size of the eyes is similar.

A bald eagle’s eyes are situated at the side of its skull. They project outward and forward so that there is an overlapping of vision, which gives the bald eagle binocular eyesight to help them gauge distances precisely. The eyes are much larger in proportion to the head but this is not very apparent, as most of the eye socket is enclosed by the skull. The relatively large eyes leave little space in the skull for the eye muscles and so the eye mobility is limited. But the bald eagle makes up for this as it has a rotating head which can turn up to a 270 degree angle.

The retina of a bald eagle is far superior to that of a human. Humans have a depression in their retina, which is called a fovea. It holds the maximum concentration of sensory cells and affords the greatest optical resolution. The fovea of the bald eagle eye has a much higher concentration of cells, which gives a better image and each eye has not just one, but two fovea! One fovea affords optimum binocular vision to the front whereas the other fovea gives the best monocular vision at the side. A bald eagle’s retina is made up of cones (to recognize color) and rods (to distinguish light). Since the retina has more cones than rods, the night vision of the bald eagle is impaired and thus it usually hunts for prey in the day. More cones help to identify hidden prey but when there is less light, the eagle perceives color in shades of gray.

A peculiar fan shaped structure called the pectin, which is full of blood vessels, is also present in the eye. It is joined to the retina and can help to supply oxygen to the retina.

A bald eagle has magnificent eyes, which change in color over the years. At birth, the eyes of the young eaglet are dark brown in color and they turn to a brighter yellow when the bald eagle matures.

Two eyelids and a circle of bones known as the sclerotic eye ring, safeguards the outer part of the eye called the cornea. The bald eagle shuts its outer eyelid while sleeping, much like a human. The inner eyelid is translucent and is referred to as a nictitating membrane. This membrane moves across the eye side to side every three to four seconds to help shield it and to keep the eye wet and clear. The lens of the eye is very soft and permits rapid accommodation. Thus a bald eagle can quickly refocus between far and near things, which in turn is a very useful ability while preying for food.

Bald eagles have unique eyebrows, which offer them further security against injury in addition to shielding their eyes from the harsh glare of the sun. A bald eagles can close its nictitating membrane and then even look directly at the sun if need be to spot their prey.

The sharp and truly extraordinary eyes are the best sense of a bald eagle. Its eyes help the bald eagle to spot its prey even at a distance of hundreds of yards. It is an intricate structure, which gives the bald eagle incredible eyesight.