The Great Horned Owl, Most Widespread Owl in the Americas

Nov 5, 2010
Bob Bowers

: Great Horned Owl in Flight - Vince Maidens

A year-round resident throughout North America, Mexico and much of South America, the Great Horned Owl is easily identified by its haunting, hooting call.

Although there are 19 species of owls in North America, none is as familiar as Bubo virginianus, the Great Horned. Like other owls, the Great Horned is a nocturnal predator, though sleeping owls are often seen during the day.

Owls

All 19 species (in 11 genera) of North American owls, except the Barn Owl, are in the family Strigidae. The Barn Owl, Tyto alba, belongs to the Tytonidae family. Owls, for the most part, are nocturnal predators that most often hunt by looking for prey from a perch. North American owls range in size from the sparrow-sized Elf Owl, at less than six inches in length, to the Great Gray Owl, a two and a half pound bird that measures 27 inches in length.

Smaller owls prey mostly on insects while larger owls prefer to kill and eat small mammals, amphibians, fish and birds, including other owls. Most prey is swallowed whole, or in the case of larger kills, torn into chunks that are swallowed whole. Unlike hawks, that eat prey leisurely in the open, most owls, including the Great Horned, avoid competition by bolting their food and retreating to cover. The digestive system of owls creates pellets from the prey's bones, exoskeletal remains, fur and other indigestible body parts. These pellets are ejected from the owl's mouth, collect under favorite roosts and provide valuable data about the owl's diet.

With relatively few natural enemies, owls are put at risk primarily through human activity. Habitat loss through logging or residential encroachment threatens certain species in particular, such as Burrowing and Spotted Owls. Attempts to control rodents with poisoned bait also kills owls that subsequently feed on the dead or dying animals.

The Great Horned Owl, Bubo virginianus

One of North America's largest owls, the Great Horned (Bubo virginianus) is just under 24 inches in length, has a wingspan of 44 inches and weighs just over 3 pounds. The Great Horned forages mostly from a perch, typically from dusk to dawn, and feeds on rabbits, rodents and similarly-sized mammals. Sometimes called the tiger owl or 'hoot owl', the familiar evening or pre-dawn call of the Great Horned is a muffled, repetitive and rhythmic hoo-oo hoo hoo hoo, suggestive of a Mourning Dove. The owls make a variety of other sounds and calls, as well, including growls, shrieks and barks. Courting females will answer a male's beckoning 'hoot' with an unexpected 'mee-ow', sounding like a treed cat.

Mostly monogamous, Great Horned Owls nest in abandoned hawk nests or build their own using sticks and bark. Nests can be found in a wide variety of locales, including trees, cactus, logs, rocks and the understructure of highway overpasses. Two to three eggs, measuring over two inches, are typical, with an incubation up to a month. The semialtricial young are cared for by both parents, and fledge in a month or more, as well. Other than those birds living in the farthest northern areas, Great Horned Owls are non-migratory. Known as well to Native Americans, representations of these owls can also be found in petroglyphs.

The species name (virginianus) originated with early European settlers in the Virginia colonies. The owl has no 'horns', but the prominent feather tufts above its eyes resemble horns, accounting for its common name.

During the day, Great Horned Owls seek cover deep in thickly-leaved trees, and their mottled coloration helps camouflage them. However, birders still find them, mostly because of their size. In addition, the birds occasionally open their eyes, and the large yellow cat-like irises are a giveaway.

The Most Widespread Owl in North America

The Great Horned Owl is found in all of the Canadian provinces (and is the official provincial bird of Alberta) as well as all 49 of the continental United States. South of the border, Great Horneds are resident throughout Mexico, parts of Central America and much of South America, including Columbia, Venezuela, Brazil, Bolivia, Paraguay, Uruguay and Argentina. Distinguished by its size, vivid yellow eyes, high-tufted 'horns' and hooting call, it is one of the most commonly recognized owls in the hemisphere.

For information about other birds of interest, see the following articles: