Skulls, eyes & eares

The Barn Owl (Tyto alba)

The Skull on your left is the Female, notice how much larger it is than the male, female owls are a third larger than the males,

The Eye of the European Eagle Owl, like all owls have a secret hidden eye lid you can see in the photo it looks like a bit of plastic. It comes from the corner and crosses over the eye, So what is the reason for this?

To keep the eye moist, polished, clean, and most of all to stop any dust entering the eye, Some owls live in dry dusty countries so when a storm blows they protect the eye by closing this membrane but they can still see shapes moving this enables them to escape from danger. The eye of the owl is to big for the socket and can only move a fraction, it is stopped from moving by a circular bone surrounding the eye called the Sclera Bone. (sclerotic ring) human eyes cannot detect the movement in owls eyes. That is why owls move their head so much,, The field of vision of the eye in an owl is 110 degrees, With a 70 degree of binocular vision, whilst humans have 180

Degree field of vision and 140 degree being binocular,

Question can they turn their head all the way around,

Answer on Questions & answers Page..........

PHOTO’S TAKEN BY TINY

Owls eyes have about 800,000 more receptors in the eyes than a human that has only about 200,000.

Owls can open up these or close them down by opening and closing the Iris, controlling the amount of light that enters the eye this enables them to see perfectly well in the dark and just as well in the day. So it makes no difference to light or dark they see just as well in both,

Eye colours differ in owls from Black, Dark Brown, Orange, to Yellow, just by looking at the eyes of the owl you can determine for yourself if it prefers to hunt by day or night, the darker the eyes hunt by night, lighter the eyes hunt by Day. But don't forget it is not uncommon to see owls at any time of day. Especially if they have young

Rare Red eyes of the Albino Barn Owl... These eyes are. Effected by the

Sun, Reaction to light is not as fast or as good as normal eyes, they can not see as well in the bright light of the sun

All photo’s by Tiny at Many Hoots centre

The Orange eyes of the European Eagle owls and some other owls are well adjusted to hunting in the sun light as well as the cover of darkness.

Day hunter as well as night hunter, The Snowy owl has yellow eyes these help the eyes to reflect the light that bounces from snow. Acting like sun glasses

Whilst other owls have Dark or a lighter Brown eye this reduces the reflection of any light that might give the game away whilst hunting at night. Dawn and Dusk.

These will also hunt during the day to feed young and when food is scares

Female

Third Bigger than the Male

Male,

Barn Owl skull

. Owls have large binocular eyes with powerful lenses and retinas made up of millions of rods. & Cones The pupils of an owl's eye can expand and Retract to collect light , even when it’s to dark for a human to see, The lens (and cornea) serve to focus this light on the retina which contains a preponderance of rods in owls. This large number of rods (retinal cells or receptors important in black and white detection) translates into excellent night vision. Short-eared owls, despite their occasional daytime hunting, possess the general blueprint of nocturnal members of the Strigiformes. (owls)

Black and white

Owls see at night in Black and White with a slight Blur vision, if you have a digital camera set it on monochrome this will allow You to see how the owl see’s. Also by day they see a blur vision Not as sharp as we do, this is one reason owls have such impeccable hearing, Some owls see better than Humans in bright light .

RODS and CONES are the light-sensitive cells inside the RETINA. These are called photoreceptors. They contain special pigments that are light- sensitive. These cells detect light coming into the eye and send a message back to the brain, which, in turn, translates the message into the things we see. Rods and cones got their names because of the shape of the cells. There are approximately 125 million RODS in each eye. Most of the rods are in the peripheral, or side, areas of the retina. They are responsible for gross detection of movement, shapes, light and dark. The vision that we obtain from rods is "black and white". They cannot detect colour. Colour vision and detailed vision come from the CONES. There are about 6.5 million cones in each eye. They are concentrated in the centre of the retina, the fovea, there are 150,000 cones in every square millimetre. Although the cones provide us with colour vision, they are not as light sensitive as the rods. In dim lighting, we rely on our rods for vision. This is why it is hard to tell the colour of an object in dark.

You can see the 3rd eye lid called the

Nictitatating membrane, this crosses

Diagonally across the eye, to clean & protect it from Dust,

Binocular

Vision 70 degree

Left monocular

vision

Right monocular

Vision total field of

Vision is 110 degree

The total field of Vision for the owl is 110 Degrees

With a binocular field of just 70 degrees.

Whilst Humans field of vision is 180 degrees with a

Binocular field of vision of 140.

Don’t let it be said that all owls ears are asymmetrically set (one higher than the other ) this does apply to the barn owl family (Tyto) and the Boreal (the Tengmalm’s owl) these two types of owls are mostly nocturnal ,this enables the bird to have all round hearing up, down, left, and right, owls hearing is not like that of a humans the owls is more acute and hears a wider range of frequencies enabling it to hear the slightest movement from a small animal under leaves or snow,

These also have a prominent facial disc, this acts as a radar dish guiding the slightest sound towards the ears. The most fascinating thing is that they can move muscles in the face and alter the shape of the disc at will, all owl bills are pointing in a downwards position this increases the area of the disc for the sound waves to filter to the ear,

So how does the owl hunt?

Lets say that a barn owl is sitting in the centre of an old disused Barn, a mouse appears from no were to the left and slightly over the shoulder the sound that the mouse makes travels towards the owl it is heard in the left ear, the owl turns his head left, because the noise the mouse made hit the left ear a split second before hitting the right ear that is why the head was turned to the left. By this time the owl is calculating the distance were the noise came from and how many wing beats it would have to do before it has caught its meal. If any.

Owls can detect a time delay from the right ear to the left ear of about 0.00003 seconds which is

(30 millionths of a second) The translation of right, left, down, and up are combined instantly inside the owls brain, the owl creates a mental image of the space that the sound is in. Studies of the owl brain in America

Have shown the medulla (part of the brain that is associated with the hearing) is much more complex than

Other birds the barn owl medulla is about 95,000 neurons three times as many as a crow.

Now that the owl has calculated were it is and the distance it starts the pounce of death towards its victim, keeping its head in line were the last noise came from, if the mouse moves to the left or right the owl will make the necessary adjustments towards the mouse, just before moment of impact the owl will close its eyes 24 –30 inches from contact depending on the speed it is travelling this will keep the eyes from harm if any fragments of dust is disturbed and enters the eyes causing a scratch which could lead to infection and possible death. With its legs out stretched in line with its eyes and the sound of the mouse, its all over until the next time.

Scroll Down for Skull

Eyes and Ears of the owl

This area is

Filled with a

Clear jelly

If The Cornea is scratched

It could become infected

And the bird could be

blinded

THIS IS THE SCLEROTIC RING THAT STOPS THE EYE FROM MOVING, MADE OF BONE,

FACT

Owls ears are so sensitive that they have a loose flap of skin that is covered in minute feathers that can cover the inner ear if noise levels are high and will shut out 95% of the noise and are opened wider if noise is of a low level is detected, Just like putting your fingers in your ears and pressing hard all noise is virtually gone

Noise to an Owl have no effect and will not damage any part of the ears.