The Creation Wiki is made available by the NW Creation Network
Watch monthly live webcast - Like us on Facebook - Subscribe on YouTube

Tawny owl

From CreationWiki, the encyclopedia of creation science
Jump to: navigation, search
Tawny owl
Tawny Owl - full body 3.jpg
Scientific Classification
Binomial Name

Strix aluco

Subspecies
  • S. a. aluco
  • S. a. biddulphi
  • S. a. harmsi
  • S. a. ma
  • S. a. mauritanica
  • S. a. nivicola
  • S. a. obrieni
  • S. a. obscurata
  • S. a. sanctinicolai
  • S. a. siberiae
  • S. a. sylvatica
  • S. a. volhyniae
  • S. a. willkonskii
  • S. a. yamadae
Tawny Owl - dark.jpg
Eurasian Tawny Owl

Tawny Owls are a species of owl with the scientific name Strix aluco. They are native mostly to Europe and Russia. They are generally nocturnal, though occasionally they are spotted in the daylight. Tawny owls are very agile birds, able to maneuver around trees and obstacles in almost complete silence. They are very vocal creatures, known for their calls. The tawny owl is perhaps most noted from its role in literature and culture. The owl was commonly thought of as a symbol of bad luck. William Shakespeare used the owl as an omen of ill-fortune in his play Julius Caesar. The poet Wordsworth wrote about the summoning of an owl in his poem About a boy. The tawny owl is also a common species found at the Eeylops Owl Emporium in the series Harry Potter by J. K. Rowling.

Anatomy

Patterning of a tawny owl's face

Tawny owls are stocky birds with rounded wings designed for gliding and use of fewer wing beats. They can be either of two colors: a deep chestnut-brown or a gray palette. Young owls are tawny-and-brown or grayish-brown. Gray and brown birds have very similar patterning; the browns are instead a myriad of grays. The upper parts of the owls are usually a tawny color, or else a chestnut hue. This coloring is mottled with dark-brown and blackish-brown streaks as well as a light tawny color. The facial disc is made of whitish feathers. These white-tan feathers also run from the facial disc back across the crown from the upper part of the facial disc. The streaks are bordered by a rim of black and brown dappling. The white facial disc is contrasted by a ruff of dappled dark brown. The rest of the face is either a light tan color or a deep tawny color with a hint of rust. Large brown-black eyes are spaced widely above an olive-yellow beak. A narrow rim of tan hems each eye. The owl’s shoulders are highlighted by the same white feathers as the facial disc. Buff colored feathers run down the wing, intermittently speckled with dark brown-black. The underside is feathered in cream with bars of dingy brown-gray. The tips of the wings are a yellow-rust color. The tectrices (small feathers that cover the bases of the large feathers of the wings and tail) are streaked brown. Blackish-brown feathers run from the tips to the primary feather (one of the main flight feathers projecting along the outer edge of a bird's wing) tectrices. This coloring forms a dark semicircle marking on the bend of each wing. The tail is colored with tawny and chestnut feathers; the outer feathers are a deep brown tipped with light gray. Their legs have feathers of white flecked with brown. Their long, black talons are ringed with white at the bases. [1]

Retina of an owl eye

Owl eyes are quite large compared to the rest of its head. A humans eye weighs less than 1 percent of the head’s eight; owls, comparatively, have eyes so large that there is almost no room for eye muscles. Therefore, they can turn their heads almost 270 degrees instead of moving their eyes. Their eyes are also formed in an oval shape. The owl’s eyes are placed on the front of its head. Owls have excellent binocular vision, having a field overlap of around 50-70 percent (compared to most bird’s 30-50 percent overlap). Its retina has around 56,000 rod cells in every square millimeter. Owls can see up to 10 times better than humans in low-light conditions. Owls have a heavy concentration of light sensitive rods in the retina, allowing their eyes to gather more light. Consequently, the concentration of color-defining cones is much lower, so while they can see well in low light, their world is not nearly as colorful. Additionally, they have very few colored oil drops since they would reduce the intensity of the light. Tawny owls have only a single fovea, and even that is underdeveloped. [2] [3]

An owl's hearing is an incredibly important asset. The owl’s ear openings are very large, located asymmetrically to provide better directional hearing. Each opening is ringed with soft, deep feathers that help to tunnel the sounds. These feathers, called auriculars, are designed to be looser than others. By using thin flaps of skin controlled by muscle movements, owls can concentrates sound waves. This skin, called a pre-aural flap, also helps to protect the ear. Facial disc feathers hide the ears and are supported by the pre-aural flap; these feathers do not, however, hinder any sounds. Even the shape of the face helps to direct sounds. Their faces are shaped like two dishes around each eye, helping to funnel sound into their ears. The eardrums are actually linked by a passageway through the skill, enabling them to detect the direction of sounds. They determine this by the time of the arrival of sound in each ear. The left ear is higher and is angled downwards; this improves their sensitivity to sounds on the ground far below. Inside the ear, there are a large number of auditory neurons. These give the owl and ability to hear even low frequency sounds from long distances. Unfortunately, even sound like the splattering of raindrops can hinder an owls ability to hear, therefore, an owl may very well starve if wet weather conditions ensue. [4] [5]

Owls make a distinctive call, but this call can serve many purposes. For the male, it is a territorial call, courtship call and an announcement when returning with food for the females. The sound is made of a long ‘hooo’ call, a sudden pause followed by a short ‘ha,’ and is finished with a sonorant warbling ‘huhuhuhooo.’ The female creates a similar call, though it is more subdued. It is said to have a more wailing sound as it is less clear than the males; it has a more hoarse quality. Another form sounds like ‘kewick’ and is used both by the male and female to contact each other. In the spring, they two may duet. The male generally replies by returning with food to the nest. This call is also used by parents to communicate with their chicks. Aggressive cries sounds something like ‘coo-wick.’ The ‘tu-whit tu-whoo’ call is notable in that is was used by William Shakespeare in Act 5, Scene 2 of Love’s Labour Lost. [6]

Owl's beak
The owl’s beak is designed to grip and tear prey. Every owl’s beak is short and curved downwards with a hooked end. The sharp, hooked ends of the beak overlap like a pair of scissors, enabling them to sever the tissues of their prey. Their bills are incredibly powerful, used to crush the prey once captured. The tips of the bill are protected by a sheath of hard, horn-like covering. The lower half of the bill is hinged and does most of the work. The upper half does, however, have a thin strip of muscle at the back where it connects to the skull. This muscle acts as a hinge for the upper beak; this allows the beak to swivel upwards, though not much. The downwards curve of the beak allows the owl’s vision to remain uninhibited. The nostrils are located on the beak, towards the base, in a spot called the cere. Almost all owls have a poor sense of smell. The bills are also used for preening and to realign the feathers. Their beaks are also an escape fore excess heat. By panting through slightly opened beaks, owls are able to cool themselves; this is called gular (having to do with the throat area) fluttering. By drawing in cooler air from the environment and exchanging it with the warm air, they are able to cool themselves. The cool air is drawn into the throat where all of the blood vessels constrict; this enables heat dispersion. [7]

Along with the bill, talons are also very effective for hunting. An owl has four toes on each foot; three in the front and one facing towards the back. Owls have a flexible joint that allows a front toe to swivel to the back when holding on to branches or prey. The other two front toes are called the ‘feather combs.’ The sharp edges help them to groom their heads. On the underside of the foot there is a rough, knobby surface that aids in gripping prey. Like other birds, owls have a locking mechanism in the foot that helps them hold securely to a branch; with this mechanism, there is no need for muscle contraction. The talons are, like the beak, very powerful. Unlike other birds, an owl’s bone structures are shorter and much stronger in the feet. This structure enables them to withstand their high impact collisions with prey. When diving for their prey, the talons are spread apart to increase the chances of capture. [8]

The owl’s silent flight is key to being an excellent predator. To accomplish such a feat, specialized feathers are needed. On the leading edge of the primary feathers, comb-like flutings are found. These flutings help to break down the turbulence. By funneling the turbulence into ‘micro-turbulences’ they can effectively muffle the noise that is so prominent during other bird's flight. Their silence also allows them to use their extraordinary hearing to the best advantage. Owls also have five other types of feathers. Contour feathers form the outermost covering of a bird. They range from the thick and stiff flight feathers to the softer contour feathers that cover the body and give shape. Contour feathers (or vaned feathers) cover the body, wing and tail. Down feathers are soft and fluffy feathers designed to trap air and create a layer of insulation next to the bird's body. Tawny owls have very few downy feathers, save for the downy barbs on contour feathers nearest the skin. Semiplumes function as a filler between the contour feathers and down feathers. Bristles are small feathers with a stiff shaft. They may have barbs around the base, but often don’t. Bristles are found around the base of the bill, around the eyes, and function as eyelashes. Filoplumes consist of a very fine shaft with a few short barbs at the end. They are almost hair-like. These feathers often serve as pressure and vibration receptors. The feet and bill are surrounded by filoplumes that help them detect things like prey. [9]

Owl skeleton
The owl’s skeleton is much like that of any other bird. Their skeleton composes only 7-9 percent of their body weight. Many of the bones separate in mammals are fused in an owl’s skeleton to provide strength. All of their bones are hollow with a thin network of supports inside. Owls have 14 neck vertebrae that allow them to rotate their head about 270 degrees, not a full rotation as is commonly assumed. The bones of the feet are typically stouter than in other birds. The bones of the wing are longer to aid in easy take-off and flight even with heavy prey. [10]

Like other birds, owls are incapable of chewing their food. They therefore will swallow their small prey whole, or else tear it apart if it is too large. But unlike other birds, owls do not have a crop; food is passed straight to their digestive system. It first passes into the proventriculus. This glandular stomach produces enzymes, mucus, and acids to begin digestion. The food then passes into the muscular stomach – the gizzard or ventriculus. This serves only as a filter; there are no digestive juices in this stage of digestion. The gizzard retains objects like bones and fur which cannot be digested. The digestible parts are then ground up and passed along to the small intestine and then through the large intestine. The pancreas and liver secrete enzymes into the small intestine. Food is also absorbed into the body while in the small intestine. After passing through the large intestine, food is transferred to the cloaca (a holding area for wastes). Wastes are then excreted. After several hours, all of the indigestible material has been compressed into pellets by the gizzard. This pellet then travels back up into the proventriculus. After another ten hours, the pellet is regurgitated. The owl is now able to consume more prey. Regurgitation only ensues after the nutrients have been absorbed from the rest of the food. [11]

Reproduction

Two tawny owl chicks

Tawny owls keep the same mate for the entirety of there lives. Almost all owls are monogamous (having only one mate during the breeding life of a pair) but some males are known to be polygamous (A mating pattern in which a male mates with more than one female in a single breeding season). Fights for their territory begin as early as October. The change in seasons from autumn to winter marks the ascertaining of territories. The size of the owl’s territory depends largely on prey and terrain. Territories can range from 30 acres up to 187 acres of land. The tawny owls are relentless when it comes to defense of their territory. It warns with a song at first, but progresses to battles with other owls and will even attack humans. They attack even in the daylight, especially if there are nestlings. Pre-breeding behavior also proceeds. The male and female owls begin to roost together, and the male begins to bring her food, straying closer to the nesting site. Courtship begins. The male will perch near the female and sway back and forth, then begins bobbing up and down, raising one wing then the other and finally spreading both wings. He fluffs his feathers, looking almost round until he compresses the feathers again. All the while he coos softly, shuffling back and forth across the branch. He might also clap his wings together. In response, the female screeches and mews, often puffing out her own feathers. Tawny owls never build there own nests; they are quite content with nesting boxes or an old raven or vulture nest, or even a squirrel’s old drey. They most often nest in the hollow of a tree.

A tawny owl in the hollow of a tree

Tawny owls can lay up to six eggs, each lain 48 hours apart. The stark white eggs are almost perfectly round. The female will incubate the little eggs for at least 28 days, then they hatch. The chicks escape their snowy white casing with the aid of an egg-tooth. This is a protrusion on the beak that then falls off within a week or so. They are born completely blind with only a thin coat of down. They gain a thicker coat, called a mesoptile, after 2 weeks. When the chicks have finally hatched, the male will return with more food. Food is brought up to 10 times a day. After a week or so, the female begins to leave to hunt. The young owls are completely dependent on their parents for food for at least three months after the leave their nest. Fledging is the process of gaining their feathers and learning to fly. Fledging takes around 30 days. The young owls slowly learn to hunt their own food and fend for themselves. The owls will reach maturity within the year and may begin breeding. But they must find their own territory; nesting within the parent’s will not be tolerated. They must either starve or find their own nesting grounds. [12] [13]

Ecology

Range Map

Tawny owls inhabit many countries: Russia, Iran and Western Siberia. They inhabit almost whole continents, such as Europe and North Africa. They are considered very common and general birds. Tawny owls generally live in broadleaved woodland and forests or the occasional coniferous forest. They may also dwell in open parklands. Tawny owls are very versatile; though they prefer woodlands, they adapt to live even in cities like Berlin and London if there are gardens and parks. Tawny owls hunt predominantly at night. They sit, alert, on their branch until disturbed a noise. In one fell swoop, the owl extends its wings to smother the prey which is usually killed by the impact. If the force doesn’t kill it, a swift peck to the base of the skull finished it off. The owl may also hunt while in flight; owls have been recorded alternating between the two methods. They have also been seen beating their wings against bushes to startle the prey out of their shelter. Owls will even eat other birds and occasional bats, usually snatching the chicks out of the nests. The owl’s diet includes such animals as rats, mice, frogs, various insects, lizards, crustaceans, mollusks, rabbits, shrews, voles and moles. [14] Tawny owls, being rather small as owls go, have various predators. Dogs, cats foxes, and other birds of prey (eagles, buzzards, hawks, and other owls) are a threat. [15] Strange though it may seem, other smaller birds will attack and owl. Their nests are in constant danger of being pillaged by rats and squirrels. They congregate in large mobs and harass the owl, usually joined by other nearby species. Surprisingly, the owl will not appear bothered by this attack, nor are they frequently injured. [16]

Superstition

Owls have, for centuries, had a significant symbolic role in many cultures. They depict such things are wisdom, good luck, death and misfortune.

An owl’s hooting can represent many ill omens. Hunters would instantly stop the hunt if they heard an owl on their left hoot three times. Many believed that hooting cause sickness; but most often it symbolized a coming death. To prevent the death, some cultures would throw salt into the fire. Others believed that an owl hooting at the moment of a child’s birth ensured an unhappy life for the child. More severely, and owl’s hoot promised the child’s death, or even that it would become a witch. It was even said that the dead will rise if an owl hooted at the funeral service. And if a pregnant woman heard an owl shriek, her child would be a girl. If you heard an owl, chances were there was a witch approaching. During cold weather, and owl screech signaled a coming storm. Indonesians used the owls call to tell whether it was safe to travel.

Owls in a person’s house predicted many misfortunes. If an owl so much as landed on the roof, someone there was foretold to die. An owl in the rafters of a house would cause a pregnant woman to miscarry. If an owl dwelt in an abandoned house, it was said to be haunted – owls were the only creatures able to tolerate ghosts. According to Irish belief, if an owl is allowed to get into and then leave your house, it will take all of the houses luck with it. Even individual parts of the owl symbolized something to past cultures. Some believed that gout (an acute, recurrent disease characterized by painful inflammation of the joints, chiefly those in the feet and hands) could be cured by eating salted owl meat. The eggs had many uses as well. In England, it was believed that burning an owl’s egg to ash and then eating the ashes would improve the eyesight. William Shakespeare presented the owlet’s wing as an ingredient for a potion in Macbeth. Witches in ancient Rome also used owl feathers in a potion. To the Greeks, an owl’s egg given to a child would make certain that the child would never become a drunkard. In India, it was believed that eating the owl’s eyes would cure eyesight. The owls nest, however, represented something a little drearier. To look into an owl’s nest brought the sorrow of depression for the rest of the person’s life.

To many cultures, the owl represented a witch. It was believed that owls were a witch’s tool, and even that witches transformed into owls to suck the blood of young children. Owls were thought to be the messengers of sorcerers and witches.

An owl’s flight brought different fortunes to every culture who interpreted it. To the Romans, they were the heralds of death. Disparately, the Greeks considered them an assurance of victory if they flew over their army at dawn.

Owls had a few other symbols as well. To the Aborigines of Australia, owls were the sacred spirits of women. In Brittany, and owl seen on the way to harvest ensured a good harvest. And in Greenland the owls were seen as a symbol of guidance. If a traveler dreamt of an owl, it predicted a shipwreck or robbery in his near future.
Greek coin

The Greeks also depicted the owl on their coinage; the owl is known as Athena Noctua (also called the Little Owl or Minerva Owl). Since the owl was a symbol of wisdom and of Athena (goddess of knowledge and foresight), they Greeks embellished their coins and jewelry with the owl for good fortune. [17] [18] [19] [20] [21]

Videos

Gallery

Creationwiki biology portal.png
Browse


References