- 18.1–24.8 in
- 39.8–57.1 in
- 32.1–88.2 oz
- Slightly larger than a Red-tailed Hawk.
- Grand-duc d'Amérique (French)
- Búsho cornudo (Spanish)
- Great Horned Owls are fierce predators that can take large prey, including raptors such as Ospreys, Peregrine Falcons, Prairie Falcons, and other owls. They also eat much smaller items such as rodents, frogs, and scorpions.
- When clenched, a Great Horned Owl’s strong talons require a force of 28 pounds to open. The owls use this deadly grip to sever the spine of large prey.
- If you hear an agitated group of cawing American Crows, they may be mobbing a Great Horned Owl. Crows may gather from near and far and harass the owl for hours. The crows have good reason, because the Great Horned Owl is their most dangerous predator.
- Even though the female Great Horned Owl is larger than her mate, the male has a larger voice box and a deeper voice. Pairs often call together, with audible differences in pitch.
- Great Horned Owls are covered in extremely soft feathers that insulate them against the cold winter weather and help them fly very quietly in pursuit of prey. Their short, wide wings allow them to maneuver among the trees of the forest.
- Great Horned Owls have large eyes, pupils that open widely in the dark, and retinas containing many rod cells for excellent night vision. Their eyes don’t move in their sockets, but they can swivel their heads more than 180 degrees to look in any direction. They also have sensitive hearing, thanks in part to facial disc feathers that direct sound waves to their ears.
- The oldest Great Horned Owl on record was at least 28 years old when it was found in Ohio in 2005.
Found all across North America up to the northern tree line, Great Horned Owls usually gravitate toward secondary-growth woodlands, swamps, orchards, and agricultural areas, but they are found in a wide variety of deciduous, coniferous or mixed forests. In some areas, such as the southern Appalachians, they prefer old-growth stands. Their home range usually includes some open habitat—such as fields, wetlands, pastures, or croplands—as well as forest. In deserts, they may use cliffs or juniper for nesting. Great Horned Owls are also fairly common in wooded parks, suburban area, and even cities.
Great Horned Owls have the most diverse diet of all North American raptors. Their prey range in size from tiny rodents and scorpions to hares, skunks, geese, and raptors. They eat mostly mammals and birds—especially rabbits, hares, mice, and American Coots, but also many other species including voles, moles, shrews, rats, gophers, chipmunks, squirrels, woodchucks, marmots, prairie dogs, bats, skunks, house cats, porcupines, ducks, loons, mergansers, grebes, rails, owls, hawks, crows, ravens, doves, and starlings. They supplement their diet with reptiles, insects, fish, invertebrates, and sometimes carrion. Although they are usually nocturnal hunters, Great Horned Owls sometimes hunt in broad daylight. After spotting their prey from a perch, they pursue it on the wing over woodland edges, meadows, wetlands, open water, or other habitats. They may walk along the ground to stalk small prey around bushes or other obstacles.
- Clutch Size
- 1–4 eggs
- Number of Broods
- 1 broods
- Egg Length
- 2.1–2.2 in
- Egg Width
- 1.8–1.9 in
- Incubation Period
- 30–37 days
- Nestling Period
- 42 days
- Egg Description
- Dull white and nearly spherical, with a rough surface.
- Condition at Hatching
- Helpless, with closed eyes, pink skin, and white down on upperparts.
Nests often consist of sticks and vary widely in size, depending on which species originally built the nest (usually Red-tailed Hawks, other hawk species, crows, ravens, herons, or squirrels). Great Horned Owls may line the nest with shreds of bark, leaves, downy feathers plucked from their own breast, fur or feathers from prey, or trampled pellets. In some areas they add no lining at all. Nests deteriorate over the course of the breeding season, and are seldom reused in later years.
Great Horned Owls typically nest in trees such as cottonwood, juniper, beech, pine, and others. They usually adopt a nest that was built by another species, but they also use cavities in live trees, dead snags, deserted buildings, cliff ledges, and human-made platforms. In the Yukon they nest in white spruces with “witches’ brooms,” which are clumps of dense foliage caused by a fungus. They occasionally nest on the ground. Pairs may roost together near the future nest site for several months before laying eggs.
Great Horned Owls roost in trees, snags, thick brush, cavities, ledges, and human-made structures. They are active mostly during the night—especially at dusk and before dawn. When food supplies are low they may begin hunting in the evening and continue into the early morning; in winter they may hunt during daylight hours. Mated pairs are monogamous and defend their territories with vigorous hooting, especially in the winter before egg-laying and in the fall when their young leave the area. Great Horned Owls respond to intruders and other threats with bill-clapping, hisses, screams, and guttural noises, eventually spreading their wings and striking with their feet if the threat escalates. They may kill other members of their own species. Crows, ravens, songbirds, and raptors often harass Great Horned Owls with loud, incessant calls and by dive-bombing, chasing, and even pecking them. Unattended eggs and nestlings may fall prey to foxes, coyotes, raccoons, lynx, raptors, crows, and ravens. Both members of a pair may stay within the territory outside of the breeding season, but they roost separately.
Great Horned Owls are common and widespread throughout much of the Americas, however populations declined throughout their range by about 43% between 1966 and 2014, according to the North American Breeding Bird Survey. Canadian populations had even greater declines—over 2.5% per year during those years—resulting in a cumulative loss of 72%. Partners in Flight estimates the global breeding population at 6 million with about 45% of in the U.S., 14% in Canada, and 7% in Mexico. They rate a 6 out of 20 on the Continental Concern Score and are not on the 2014 State of the Birds Watch List. Great Horned Owls were heavily hunted until the practice was abolished in the mid-twentieth century. Some illegal hunting continues. Northern populations rise and fall in cycles along with prey populations. The species adapts well to habitat change as long as nest sites are available. In the Pacific Northwest they have expanded into open land recently created by logging. Because of their prowess as predators, Great Horned Owls can pose a threat to other species of concern, such as Peregrine Falcons and Spotted Owls. Owls are sometimes poisoned by pesticides and other toxic substances that have accumulated in their prey.
- Houston, C. S., D. G. Smith, and C. Rohner. 1998. Great Horned Owl (Bubo virginianus). In The Birds of North America, No. 372 (A. Poole and F. Gill, eds.). The Birds of North America Online, Ithaca, New York.
- IUCN. 2012. IUCN Red List of Threatened Species (ver. 2012.1).
- North American Bird Conservation Initiative, U.S. Committee. 2014. State of the Birds 2014 Report. U.S. Department of Interior, Washington, DC.
Partners in Flight. 2012. Species assessment database.
- USGS Patuxent Wildlife Research Center. 2015. Longevity Records of North American Birds.
- USGS Patuxent Wildlife Research Center. 2014. North American Breeding Bird Survey 1966–2014 Analysis.