why an owl can see at night?

Answer 1

They can see better for two reasons. One is that the pupil of their eye has much greater range and muscular control than ours, so they can open it to gain more light. The other is called a facial disc, and is found on owls that are active at night. (Not all owls are nocturnal. Snowy Owls among others are diurnal, active at day.) The facial disc acts almost like the reflectors around a bulb in a car headlight or lighthouse, except instead of focusing light going out, they create a light trap that helps funnel and reflect light into the eye.

The kicker is that owls do not hunt visually, but by sound. Their ears are designed for amazing sound reception with the feathers around them funneling in sound from all around, unlike our ears which focus forward. In addition, the ears on an owl's head (not the feathers that stick up as they have nothing to do with the ears) are not on the same point on each side. By being intentionally offset, the ears can actually allow and owl to triangulate on a sound from the wing and attack it in total silence!

Answer 2

As most owls are active at night, their eyes must be very efficient at collecting and processing light. This starts with a large cornea (the transparent outer coating of the eye) and pupil (the opening at the centre of the eye). The pupil's size is controlled by the iris (the coloured membrane suspended between the cornea and lens). When the pupil is larger, more light passes through the lens and onto the large retina (light sensitive tissue on which the image is formed).
The retina of an owl's eye has an abundance of light-sensitive, rod-shaped cells appropriately called "rod" cells. Although these cells are very sensitive to light and movement, they do not react well to colour. Cells that do react to colour are called "cone" cells (shaped like a cone), and an Owl's eye possesses few of these, so most Owls see in limited colour or in monochrome.
Since Owls have extraordinary night vision, it is often thought that they are blind in strong light. This is not true, because their pupils have a wide range of adjustment, allowing the right amount of light to strike the retina. Some species of Owls can actually see better than humans in bright light.

Answer 3

Owl Eyes and Vision
Compiled by Deane P. Lewis 1999-03-28, last updated 2005-07-24

Eagle Owl Eyes


Owl Skull shows Sclerotic rings


Nictitating membrane


Nictitating membrane

Of all an Owl's features, perhaps the most striking is its eyes. Large and forward facing, they may account for one to five percent of the Owl's body weight, depending on species. The forward facing aspect of the eyes that give an Owl its "wise" appearance, also give it a wide range of "binocular" vision (seeing an object with both eyes at the same time). This means the owl can see objects in 3 dimensions (height, width, and depth), and can judge distances in a similar way to humans. The field of view for an owl is about 110 degrees, with about 70 degrees being binocular vision.



By comparison, humans have a field of view that covers 180 degrees, with 140 degrees being binocular. A woodcock has an amazing 360 degree field of view, because its eyes are on the side of its head. However, less than 10 degrees of this is binocular.

An Owl's eyes are large in order to improve their efficiency, especially under low light conditions. In fact, the eyes are so well developed, that they are not eye balls as such, but elongated tubes. They are held in place by bony structures in the skull called Sclerotic rings. For this reason, an Owl cannot "roll" or move its eyes - that is, it can only look straight ahead!
The Owl more than makes up for this by being able to turn its head around, and almost upside-down. It is able to achieve this by having a long and very flexible neck, which is not always apparent, as it is hidden by feathers and the Owl's posture. An owl's neck has 14 vertebrae, which is twice as many as humans. This allows the owl to turn its head through a range of 270 degrees measured from a forward facing position.

Cross-section of an Owl's Eye

As most owls are active at night, their eyes must be very efficient at collecting and processing light. This starts with a large cornea (the transparent outer coating of the eye) and pupil (the opening at the centre of the eye). The pupil's size is controlled by the iris (the coloured membrane suspended between the cornea and lens). When the pupil is larger, more light passes through the lens and onto the large retina (light sensitive tissue on which the image is formed).
The retina of an owl's eye has an abundance of light-sensitive, rod-shaped cells appropriately called "rod" cells. Although these cells are very sensitive to light and movement, they do not react well to colour. Cells that do react to colour are called "cone" cells (shaped like a cone), and an Owl's eye possesses few of these, so most Owls see in limited colour or in monochrome.
Since Owls have extraordinary night vision, it is often thought that they are blind in strong light. This is not true, because their pupils have a wide range of adjustment, allowing the right amount of light to strike the retina. Some species of Owls can actually see better than humans in bright light.

To protect their eyes, Owls are equipped with 3 eyelids. They have a normal upper and lower eyelid, the upper closing when the owl blinks, and the lower closing up when the Owl is asleep. The third eyelid is called a nictitating membrane, and is a thin layer of tissue that closes diagonally across the eye, from the inside to the outside. This cleans and protects the surface of the eye.

References:

Campbell, Wayne. 1994. "Know Your Owls (CD-ROM)". Axia Wildlife
Hollands, David. 1991. "Birds of the Night". Reed Books
König, Weick and Becking. 1999. "Owls: A Guide to the Owls of the World". Yale University Press
Long, Kim. 1998. "Owls: A Wildlife Handbook". Johnson Books
Mikkola, Heimo. 1983. "Owls of Europe". Buteo Books

Answer 4

All animals, regardless of species require light in order to see. So it's not that owls can see in total darkness (though they can hunt in total darkness using only sound (this is not the same as ecolocation).... owls and other nocturnal predators have very good low light vision. Owls in particular have very good distance vision, but cannot see very well right in front of them. I assume this is the only downfall to their incredible eyesight.

In essence, owls see at night the same way you and I see during the day. Rods translate the images formed by light and dark patterns and cones (only existing in certain species, mostly mammals) translate the color.... owls do not likely have cones so their vision is more "tuned" to seeing very fine shades of gray, which is what makes their ability to see in dim light so much better than ours.

Edit: to those people who answer questions with their own words instead of copy pasting someone else's: thank you. A lot of copy pasted answers have excess information that is not relative the the particular question.

Answer 5

OWLS

Owls are interesting birds. They are raptors. That means they catch other animals for food.

Most owls are nocturnal. They hunt at night and roost during the day. They have special eyes that help them see at night because the pupil gets so big it covers most of the eye and lets in more light. Their eyes are bigger than most birds and take up more room in their head than their brain does. The owl has to turn its head to look from side to the side because it cannot roll its eyes. Owls can focus on objects both near and far at the same time. A great gray owl can see a mouse two football fields away. Owls also have a third eyelid which keeps the eye moist and helps protect the eye.

It seems like an owl doesn’t have a neck but it does. It has fourteen bones in its neck. It can turn its head farther around than we can. It can look behinditself. Sometimes it seems to have its head on backward. It can also turn its face upside down.

Owls have excellent hearing. They sit quietly on a tree branch and listen to find its prey. Some owls have one ear lower than the other. The right ear hears best from below and the left ear hears best from above.

They are not fast fliers but they can fly very quietly. Soft fringes on the edges of most owl’s wing feathers may help them do this.Their other feathers are also very soft which helps them move quietly. Baby owls are covered with feathers called down. They molt, or shed, these light feathers when they get older and grow adult feathers. Their bones are light and full of air pockets

Most owl’s legs are covered with feathers.They have four strong toes, two point forward and two point backward to help it grab things. Sharp talons, or hooked claws, are at the end of each toe to help them hold their prey, or food, tightly.

Owls usually swallow their food whole, headfirst. Their body cannot digest hair, feathers, or bones so this is regurgitated, or spit up, as small balls called pellets. These owl pellets can be fun to look through because you can see the bones of the animal the owl had for lunch. Most owls eat rodents, small mammals, snakes, insects, and small birds.

Answer 6

Ohhh, they wear owl contact lens with special inner eyelid- thats why they can see very well at night. They can also see during the day.

Answer 7

Is that a question or comment, lol. Owls can see the infrared part of the light spectrum.

Answer 8

just like any other animal it can see at night it has those eyes that are like green night vison googles they use for police things. it also has those eyes that can move in different ways unlike peoples because they have a big flat nose in there way.

Answer 9

because birds have 4 cone cells and humans have only 2 cone cells.

Answer 10

they dont see as well as people think they are more like bats and use sound waves