Dense forests, deserts and plains to city parks; have been known to inhabit the same areas as the diurnal red-tailed hawk

In the wild, they eat at least 253 different prey items.  The preferred diet is made up of rabbits and hares. Mammalian prey includes all coexisting rodents, squirrels, mink, skunks, raccoons, armadillos, porcupines, domestic cats and dogs, shrews, moles, muskrats, and bats. Bird prey includes all other owls (except snowy owl), grouse, woodpeckers, crows, turkeys, pigeons, red-tailed hawks, bitterns, great blue heron, ducks, swans, gulls, etc. Reptiles include snakes, turtles, lizards, and young alligators. Amphibians include frogs, toads, and salamanders. Other foods include fish, large insects, scorpions, centipedes, crayfish, worms, spiders, and road kill.  In the Zoo, they are fed bird of prey diet, mice, rats and chicks.

Not listed, but all birds of prey are protected by law.

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.  Prey is usually killed instantly when grasped by its large talons.  A great horned owl may take prey 2 to 3 times heavier than itself.  They also hunt by walking on the ground to capture small prey or wading into water to snatch frogs and fish. They have been known to walk into chicken coops to take domestic fowl.  Rodents and small rabbits can be swallowed whole while larger prey is carried off and ripped apart at feeding perches or at the nest.  Birds taken as prey are often plucked first, and legs and wing tips discarded.

Great horned owls are residents year-round; however, those living in the northern part of the species' range may migrate south during colder weather.

The nesting season is in January or February when the males and females hoot to each other. When close they bow to each other, with drooped wings. Mutual bill rubbing and preening also occurs. They do not build a nest of their own but utilize the nests of other birds such as the hawk, crow and heron. They may also use squirrel nests, hollows in trees, rocky caves, abandoned buildings, or artificial platforms. They are extremely aggressive when defending the nest and will continue to attack until the intruder is killed or driven off. Normally, two to four eggs are laid and incubated by the female for 26-35 days. Young start roaming from the nest onto nearby branches at 6 to 7 weeks, when they are called "branchers", but cannot fly well until 9 to 10 weeks old. They are fed for another few weeks as they are slowly weaned. Families remain loosely associated during summer before young disperse in the autumn. Adults tend to remain near their breeding areas year-round while juveniles disperse widely, over 250 km (150 miles) in autumn. Territories are maintained by the same pair for as many as 8 consecutive years; however, these owls are solitary in nature, only staying with their mate during the nesting season. Average home ranges in various studies have been shown to be approximately 2½ square kilometers (1 square mile).

Hearing is very acute and in many species the ears, which are crescent-shaped slits beneath the facial feathers, are placed asymmetrically (unevenly) on the head.  Sound waves reach each ear at different times, giving the sound a directional quality.  Owls also have a distinctive facial disk that directs sound towards the ears. The flight of an owl is virtually silent due to tiny fringelike structures found along the outer edge of each feather. This allows an owl to fly quietly toward its prey without detection.  Great horned owls have a large repertoire of sounds, ranging from deep booming hoots to shrill shrieks. The male's resonant territorial call "hoo-hoo hoooooo hoo-hoo" can be heard over several miles during a still night. Both sexes hoot, but males have a lower-pitched voice than females. They give a growling "krrooo-oo" or screaming note when attacking intruders. Other sounds include a "whaaa whaaaaaa-a-a-aarrk" from disturbed birds, a catlike "MEEE-OWww", barks, hair-raising shrieks, coos, and beak snapping. Some calls are ventriloquial. Most calling occurs from dusk to about midnight and then again just before dawn.

The great horned owl was first seen in the Virginia colonies, so its species name was created from the Latinized form of the name of this territory (originally named for Queen Elizabeth I, the "Virgin Queen").

Johann Gmelin made the first published description in 1788.

The owl is a bird with a poor reputation despite being known for being extremely wise, hence the expression being a 'wise old owl'.  Perhaps this stems from the fact that the owl leads a nocturnal and solitary existence and that the night has long been associated with the time when darker forces and negative energies are present. To see one by day is unlucky and to experience one flying around the house at night signals that death is present, which is thought to stem back to Roman times when the historian 'Pliny' in AD 77 was quoted as saying the bird was 'most execrable and accursed' and always brought bad news. Should an owl brush its wings against a window pain or be seen perching for a considerable length of time on a roof then it is traditionally believed that illness and even death is present within.  To look into an owl's nest is reputed to leave the observer with a sad and morose soul.  According to an old Welsh (UK) tradition if you hear an owl hooting amongst a densely built up area then a female in the locality is said to have just lost her virginity!  To hear the hoot of the owl when pregnant, it is traditionally believed in France that the baby will be a girl.  In Germany if an owl is heard as a child is being born then the life will be an unhappy one.

A dead owl has served many purposes including mixing some of the flesh with boar's grease as an ointment to ease the pain of gout.  Owl broth was once used to feed children to avoid whooping cough according to British tradition, perhaps because the owl itself never suffered in pain when making a similar sound. The eggs were also once thought to help prevent epilepsy, bad sight (for obvious reasons), and more amusingly to bring drunks back to their senses.

It is illegal to possess any species of a raptor alive or dead without special permits, or to knowingly kill or injure one in any way.