A great horned owl hunts mostly at night. The iris of a great horned owl is yellow, except in the South American great horned owl, where it is amber. A great horned owl's night vision is excellent, in black and white rather than color. A great horned owl has binocular vision, which gives excellent frontal vision but weaker peripheral vision. An owl turns its head to look around, because its eyes do not move in the sockets, and it can turn its head about 270 degrees, which is three-quarters of the way around a circle.

A great horned owl has keen hearing and keen vision in low light. Great horned owls have better depth perception and better perception of sound elevation (up-down direction) than humans. An owl can pinpoint both the horizontal and vertical direction of a sound, and a great horned owl is keenly attuned to high-frequency sounds, such as those made by squeaky-voiced rodents. Special flight feathers let an owl fly down silently, and great horned owls have soft, fluffy feathers that keep them warm in colder climates. A great horned owl's hoot is low and deep, and you can hear great horned owls hooting at night in winter.

A great horned owl watches from a high perch, then swoops down to catch its food. Great horned owls eat rabbits, rats and squirrels, and up to 90 percent of a great horned owl's diet is mice, voles, squirrels and other small mammals. Great horned owls have the widest prey base of any North American owl, and a great horned owl may eat more than 4,000 mice per year. To a lesser extent, they also take reptiles, amphibians, fish and large insects. A great horned owl swallows small prey whole, and it coughs up pellets of the bones and fur it cannot digest.

An adult great horned owl is between 18 and 25 inches long, and a great horned owl's wingspan can reach about 1.5 meters (5 feet). The Wildlife Science Center says great horned owls generally weigh between 2.2 and 3.8 pounds, and the Animal Diversity Web gives an average mass of about 1.7 kg for female great horned owls and 1.3 kg for males. The Owl Research Institute lists adult male great horned owls at 1304 g (2.9 lb) and adult females at 1509 g (3.3 lb). Great horned owls are the largest North American owls with ear tufts.

The great horned owl is the most widely distributed true owl in the Americas, and it lives across most of North America. Great horned owls are most commonly found in areas where woodland and open fields are mixed together, and they live in many places, including the countryside and cities. Mated great horned owls stay in their territory all year, and the Animal Diversity Web says great horned owl territories are generally 5.26 to 5.56 square kilometers in area. The Peregrine Fund lists the great horned owl's status as Least Concern, as of November 2026.

Great horned owls start nesting early, in winter. Great horned owls do not build their own nests, and they add little or no nest material, aside from feathers at times. They use nests built by other large birds, such as hawks and crows, and a great horned owl may also nest on a cliff ledge, in a cave, in a broken-off tree stump, or sometimes on the ground. In Vermont, great horned owl nests have been found in borrowed hawk and heron nests and in broken tree stubs. A great horned owl usually lays two or three eggs, and the eggs hatch in about a month.

Baby great horned owls are covered with down when they hatch. While the female sits on the eggs, the male brings her food, and both parents help feed the young owls. Young great horned owls leave the nest and climb out onto nearby branches at about 5 to 6 weeks old, and they can fly well at about 9 to 10 weeks old. Great horned owls in captivity may live more than 20 years.

Words to know

• binocular: two-eyed
• peripheral: at the sides
• perch: a high seat
• pellets: small lumps
• territory: claimed area