Owls are famous for their vision. With their great ability to detect and capture small prey even on the darkest nights, they do not possess round eyeballs like we do. Instead, they are elongated and sit on “sclerotic rings,” a bony structure in the skull. Owls have binocular vision similar to humans in that their eyes are directed forward, giving them (and us) a great ability to judge height, weight, and distance. However, while humans have a 180-degree field of view, with about 140 degrees of binocular vision, owls only have a 110-degree field of view with about 70 degrees of binocular vision. What they lack in binocular vision they make up for with their legendary night vision and farsightedness.
Its shape also provides a comparatively larger retina size that is packed with light-sensitive rods, leading to the extraordinary light-gathering properties of the owl’s eye that are enhanced in many species by a reflective layer behind the retina called tapetum lucidum , which reflects back onto the rods any light that may have passed through the retina without hitting it the first time.
What species of owl has the best vision? It appears that griffon owls have the best developed eyes of all varieties of owls, including all vertebrates, probably around 100 times more sensitive at low light levels than our vision.
And what about the color of your iris? It is a fascinating aspect. The color of the iris is related, in part, to the time of day or night an owl hunts. Although it is not strictly observed in all species of owls, the color of the eyes tends to indicate what time of day owls prefer to be active. There are always exceptions, but most of them hunt around the same time as other owls of the same color as the eyes, according to Raptor Rescue, a bird of prey rehabilitation charity. This link is not fully understood, but there is plenty of evidence: species eye color correlates with periods of daily activity.
Colors tend to be dark brown or black for strictly nocturnal owls, orange (and almost red) for twilight owls that hunt at dawn and dusk, and yellow for diurnal owls that hunt during the day.
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