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Archive - January 2015
Owls are secretive but magnificent birds. They play an important role in our environment as predators. Most of them are active at night.
What is an owl? Owls are included in a group of birds known as raptors. Hawks and falcons are considered to be raptors, too. Raptors are birds of prey that have large eyes that face forward, powerful talons and a hooked beak. They have excellent senses of vision and hearing.
Talons are claws. A talon is found at the tip of each of the eight toes. Talons are made of keratin and are extremely sharp. The downward-curving shape, sharpness and length of the talons make it hard for owls to walk. Strong leg muscles and toes along with the talons provide the weaponry needed to capture food.
Raptors have ear openings on each side of the head behind and beneath the eyes. The ears are usually covered with feathers.
Raptors have the best vision in the animal kingdom. The location of their eyes in the front of the head gives them a wide field of view and binocular vision. The eyes of these birds are so large that they cannot move within the eye socket. Owls cannot see in total darkness but are capable of vision in very dim light. The retina of the eye has structures that are very sensitive to light but not to color. The pupil in each eye functions independently, an advantage when hunting in areas of varied light and shadow.
The beak, or bill, is made of bone and covered with keratin. Raptors have a hooked tip to the beak. The edges of the beak are very sharp. The hooked beak is used to tear meat into pieces that can be easily swallowed. There is a soft, fleshy area at the base of the upper bill that does not contain feathers. This area helps raptors to keep the area around the bill clean. Owls eat their prey whole or in large chunks. They cannot digest everything that they swallow, and these parts (fur, feathers, bones, etc.) cannot pass easily through the owl's digestive tract. To get rid of them, the owl compresses them and removes them through its mouth as a "pellet." You can determine what an owl has eaten by analyzing the contents of its pellets.
Owls have some traits that make them different from the other raptors, though. Owls have fringed outer wing feathers for silent flight. Owls make almost no sound when they fly. Silent flight is a great assistance for catching prey. Their wings are rounded and very large for their body size. The tail is short. They can turn their head around 270 degrees. This feature allows them to look nearly all the way around them when they are perched and helps them greatly since their eyes are focused forward and can only see what is in front of them. Owls have a rounded face that helps them to direct sounds to their ears. Some owls have ear tufts. These are feathers that stick up above the ear and aid in directing sound into the ear holes.
Those owls that nest in Illinois use a variety of nesting strategies. Depending on the species, the nest location may be on the ground, in a tree cavity, in a nesting box, in an old nest of another bird species or in abandoned buildings or other human-made structures.
Eight species of owls are regular residents of or visitors to Illinois. You can read more about them below. A few other owl species are sometimes seen in Illinois, but those birds have traveled away from their normal territory.
barn owl (Tyto alba) – The barn owl nests and roosts in old barns and other abandoned buildings near prairies, farms, marshes and open areas. It has a white, heart-shaped face and long legs. The middle talon on each foot is serrated. This bird is 16-24 inches long with a wingspan of 38-45 inches. Its prey items include mice, voles, insects, ground squirrels and small birds. It is an occasional permanent resident in southern Illinois and a rare permanent resident in the rest of the state. Its call is "snore," "kschh" or "shiish."
eastern screech-owl (Megascops asio) – A common permanent resident of Illinois forests, swamps, parks, gardens and orchards, the screech-owl is very small (7-10 inches long; wingspan 20-22 inches) and has ear tufts. The body feathers may be either red-brown or gray. It hunts at night for rodents in winter and insects in summer. This species nests in tree cavities and readily uses nesting boxes provided by humans. Its call is an eerie "whinny."
great horned owl (Bubo virginianus) – This adaptable species lives in woodlands, city parks and suburban areas statewide. It has a flattened face with large yellow eyes, long ear tufts and a black bill. Its length of 21-22 inches and wingspan of 48-62 inches make it the state's largest resident owl species. Hunting at night, it feeds on small owls, hawks, waterfowl, mice, reptiles, skunks, squirrels and voles. It nests very early in the year (as early as December) and uses a tree cavity, an old nest of another bird species or sometimes even the ground to place the eggs. The call of this fierce and aggressive bird is "hoo, hoo-oo, hoo, hoo."
snowy owl (Bubo scandiacus) – The snowy owl may visit Illinois in winter, in open areas, fields, around lakes and on golf courses in northern and central Illinois. Its body feathers are white with black markings. This large owl (22-24 inches long; wingspan of 51-71 inches) hunts during daylight for its prey of mice, cottontails, voles, birds, fishes and dead animals. Its feet and toes are layered with feathers, a trait unique to this species and needed in its usual Arctic range. Its call is "krowow" and is only made during the mating season.
barred owl (Strix varia) - This large bird (20-21 inches long; wingspan 38-50 inches) lives in woodlands and open areas near rivers and swamps. It is a common permanent resident of the state. Its prey consists of mice, amphibians, birds, crayfish, fishes, insects and small mammals. Both horizontal and vertical dark stripes can be seen on its belly feathers. The nest is placed in a tree cavity, an old nest of another bird species or in a human-made nesting box. Its call is "Who cooks for you? Who cooks for you all?"
long-eared owl (Asio otus) - A winter resident in Illinois, the long-eared owl (14-15 inches long; wingspan 35-39 inches) lives in densely wooded areas that are near the open grasslands where it hunts at night. This species feeds mainly on small mammals. It is a thin owl with vertical streaks on the breast feathers, long ear tufts and black feathers around the eyes. The eyes are brown, and the beak is tiny and yellow. Its call is only produced in the mating season and is a series of "whoo" sounds.
short-eared owl (Asio flammeus) – The short-eared owl is a rare winter and summer resident of marshes, meadows, fields and parks. It has very short ear tufts. The eyes are yellow and are circled by dark feathers. This bird is 13-17 inches long with a wingspan of 38-44 inches. Rodents, insects and small birds are the prey species that it hunts for in late afternoon and early evening. It is known to play dead when threatened. Its call is "kee-yow wow." Its nest is placed on the ground.
northern saw-whet owl (Aegolius acadicus) – The northern saw-whet owl (7-9 inches long; wingspan 18-24 inches) is a winter resident of Illinois woodlands. This small owl has no ear tufts. Other identifying features are red streaks on the belly feathers, white streaks on the forehead feathers and a black bill. It hunts at night, feeding on small mammals.
Two species of owls are currently listed as "endangered" in Illinois. Destruction of grassland and wetland habitats are the main factors related to the small numbers of short-eared owls in Illinois. This species' populations also fluctuate based upon the abundance of the small mammals that it eats. The barn owl was once fairly abundant in Illinois. Its decline seems to be related to changing agricultural practices and the loss of grassland and marsh habitats.