Great Horned Owl
Good times to observe
Average Length: 18-25 in., Wingspan: 36-60 in. Great Horned Owls are the largest year round resident owl in Illinois. They can vary in color from a reddish brown to a grey or black and white. Their underside is a light grey with dark bars and a white band of feathers on the upper breast giving them it a barred or mottled look that is excellent to camouflage themselves against tree trunks. They have large, yellow-orange eyes bordered in an orange/rusty facial disc. Their name is derived from tufts of feathers that appear to be “horns” which are sometimes referred to as the “ear tufts”, which have nothing to do with their ears or hearing at all. Their feet are feathered all the way down to their toes.
DuPage County Notes
Owls have spectacular binocular vision allowing them to pinpoint prey and see in low light. The eyes of Great Horned Owls are nearly as large as those of humans and are immobile within their circular bone sockets. Instead of turning their eyes, they turn their heads. Therefore, their neck must be able to turn a full 270 degrees in order to see in other directions without moving its entire body.
An owl's hearing is as good as – if not better than – its vision; they have better depth perception and better perception of sound elevation (up-down direction) than humans. This is due to owl ears not being placed in the same position on either side of their head: the right ear is typically set higher in the skull and at a slightly different angle. By tilting or turning its head until the sound is the same in each ear, an owl can pinpoint both the horizontal and vertical direction of a sound.
Great Horned Owls are some of the earliest-breeding birds in DuPage County. They breed in late January or early February and are often heard calling to each other in the fall, starting in October. They choose a mate by December and are often heard duetting before this time. Both sexes may be very aggressive towards intruders when nesting.
They often take over a nest used by some other large bird, sometimes adding feathers to line the nest but usually not much more. Old crow, Red-tailed Hawk or large squirrel nests are often favored in North America. However, they are far from dependent on the old nests of others and may use cavities in trees and snags, cliffs, deserted buildings, and artificial platforms.
Even though the female Great Horned Owl is larger than her mate, the male has a deeper voice. Pairs often call together, with audible differences in pitch.
Great Horned Owls hunt by perching on snags and poles and watching for prey, or by gliding slowly above the ground. From high perches they dive down to the ground with wings folded, before snatching prey.
An extremely wide range of prey species (over 250 identified) are captured, but rabbits and hares are its preferred prey. Mammalian prey includes all coexisting rodents, squirrels, mink, skunks, raccoons, armadillos, porcupines, shrews, moles, muskrats, and bats. The Great Horned Owl is the only animal that regularly eats skunks.
Great Horned Owls have adapted to many different places and climates. They occur in habitats from dense forests, deserts and plains to city parks. They have been known to inhabit the same area as the diurnal red-tailed hawk.
Great Horned Owls are found throughout North America from the northern treeline and then in Central and South America. They are resident year-round in Illinois, however, birds living in the northern part of the species' range may migrate south.
Activity generally begins at dusk