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July 14, 2012
Melina Peters, Naturalist, Little Red Schoolhouse

The Great horned owl is the largest of the ten raptors known to Wolf Road Prairie. Great horned owls weigh between 3 to 4 pounds and have wing spans reaching 36-60 inches.

Great horned owls are identified by their "horns" or feathered ear tufts on the top of their heads. They are nocturnal and normally hunt at dawn and dusk. The female is larger than the male.

It is easier to see owls in winter when trees are leafless and the landscape is barren. The coloration of the owl's feathers provides excellent camouflage for the bird in all seasons and all habitats.

Owls nest in winter. The female will lay two to three eggs with thick shells in February. The incubation period is about 28-30 days. When the young hatch, they are covered with pure white down. At one week old, the down begins to turn gray on the back and wings. By two weeks old, the young owls are buff colored.

The young owls brood at three to four weeks of age. The parents are kept very busy hunting for the babies and typically bring 13-17 mice to the nest each night. They stay with their young and continue to hunt for them until they are fully grown. The young owls are unable to fly until they are about ten to twelve weeks old.

Sometimes, a baby owl will fall from the nest. It is never a good idea for humans to try to help the baby owl back to its nest. The baby is a good climber and is well equipped with sharp talons and beak to get back to its nest on its own.

Owls are not the best nest builders and will sometimes occupy an old red-tailed hawk nest while the hawks are away. By the time the hawks are ready to return, the baby owls are fully grown and fledged and the nest has been vacated. Owls are also known to nest in tree hallows or in the high forks of strong branches of large trees.

Owls prefer a diverse diet of mice, squirrels, gophers, mink, weasel, voles, shrews, woodchucks and rabbits. They are the only predator to eat skunks. They have evolved to survive at the top of their food chain. Owls digest the soft tissue of their prey and compress bone and hard tissue and fur into pellets. Studying these pellets reveals what the bird has been hunting and eating.

Great horned owls can be identified by:

Ears with feathered tufts arranged asymmetrically on the skull. The owl hears above and below the ears.

Binocular vision. Large eyeballs are deep set and fixed forward. Windshield-like thin opaque membranes cover and protect the eyes when the owl goes into a dive after prey.

The hooked beak keeps growing from a bony plate in the skull called the cere.

Each feather is controlled by its own muscle. Different feathers serve different purposes for flight and hunting.

When closed, the razor sharp talons can apply 300 pounds of pressure on prey. Owls can capture and carry prey as heavy as nine to ten pounds. The owl's feet are feathered.

The skeletal system is rigid and light and filled with air spaces for fast and easy flight. The air chambers are strong and contain no bone or marrow.

Owls can rotate their heads about 370 degrees in one direction at a time.

Owls do not migrate. They survive the winter by regulating their body temperature as weather conditions change. An owl can raise its body temperature on a cold night from 99.8 degrees to 112 degrees. Owls can triple their metabolic rate in response to cold. To stay warm, an owl will often tuck its beak into a wing. Owl feathers have evolved for warmth. Owls fluff their feathers to circulate and warm air around their bodies. Owls also are also known to keep warm by communal roosting.

Great horned owls, raptors and all migrating birds are protected under the Migrating Bird Act. Personally possessing feathers or any bird parts is a violation of Federal law and subject to penalty.

Following Melina's power point presentation, she took the male Great horned owl pictured here from his holding cage and held him on her gloved arm for us to see up close and personal. For a quite a while, he observed us carefully and seemed to enjoy being the center of attention.

Melina explained that one of his wings had been badly injured when he was a young bird and that as a result, he is unable to fly. She believes he is about 16-17 years old and has been in the care of naturalists at the Little Red Schoolhouse Nature Center for about 15 years.

Melina explained that some of her duties involved in caring for him include filing down his beak. Owls in the wild do this naturally but a captive owl does not have the surroundings to keep its beak from growing too long. Melina also told us that she regularly takes him for walks in the woods to improve his quality of life. This gives him the opportunity to see trees and enjoy being in the forest. Otherwise he would spend his entire life confined to a large cage.

The Little Red Schoolhouse Nature Center is licensed to care for injured raptors. A Great horned owl can live up to 40 years in captivity but only about 20 years in the wild.

For more information about the raptors being cared for at the Little Red Schoolhouse Nature Center operated and maintained by the Forest Preserve District of Cook County, call 708-839-6897.

Photos by Tom Lovestrand

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