Great Horned Owls
Author: Bruce Neville

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Scientific Name: Bubo virginianus Common Name: Horned Owl, Tiger Owl, Great Horned Owl Spanish Name: Búho cornudo, Búho águila, búho gigante, búho real, tecolotón

Description:
The Great Horned Owl is the largest owl in New Mexico. They are even larger than a crow. Their heads are large and have earlike or hornlike tufts of feathers. Their faces are flat and reddish-brown. Their eyes are yellow and large (even for an owl). They have a moustache of pale feathers above their dark bill. The rest of their plumage (feathers) are mottled (freckled) in shades of brown and gray, with narrow blackish bars on the breast. Desert-breeding birds in New Mexico are grayer than those in wetter areas of the country. Males and females look alike. Young birds often have tufts of downy white feathers among the adult feathers.

Geographic range:
The Great Horned Owl lives throughout nearly all of North America, except for the most barren areas of the Arctic. They also occur in parts of South America. Great Horned Owls are not migratory, so they stay pretty close to home for throughout the year. They can be found all over New Mexico.

Habitat:
The Great Horned Owl occurs in most habitats in the state, including riparian forests (forests along waterways), ponderosa pine forests, and deserts. Their home range usually includes some open areas where it is easier for them to hunt. They are adaptable and can usually live around humans, so they can often be found in cities and towns.

Food Web:
The Great Horned Owl is a powerful nocturnal predator (they hunt at night). They generally capture prey by pouncing from a perch. They will catch and eat almost anything from insects to jackrabbits. Rabbits and rodents are their most common food. It often preys upon nestlings (the young) of large birds, like hawks and ravens. They regurgitate (throw up) the parts they cannot digest as pellets, which gather below their regular roosting trees. Individual prey can easily be identified from the tiny bones that are left along with the pellets.

Nestlings may be attacked and killed by crows or ravens. The nestilings that fall out of the nest too soon can be attacked by carnivorous (meat eating) mammals on the ground. Adult great horned owls generally have few predators, although adults will kill other Great Horned Owls for territory. Great Horned Owls have also been known to attack porcupines. Both the owls and the porcupinces can be killed in these attacks.

Reproduction and Development:
Great Horned Owls mate for several years, possibly for life. They nest in a wider mix of habitats than any other North American bird. They may steal the nest of a hawk or raven or they may build in a hollow stump. They may also nest on the ground or on a ledge of a cliff, cave, or lava tube. Great Horned Owls use little or no nesting material.

They generally lay 2 to 3 nearly round and spherical white eggs, and only the female incubates (takes care of the eggs). They lay their eggs in winter or early spring. The eggs hatch in about a month, and the young are born naked and with their eyes closed. The young fledge (leave the nest) about two months after hatching, but they are fed by both parents for several months after they leave the nest. Great Horned Owls generally do not nest until they are two years old. A Great Horned Owl that is caught, studied and banded as an adult lived an additional 28 years.

Behavior:
Great Horned Owls are mainly active at night (nocturnally), even though they begin hunting at dusk. Owls have a very strong sense of hearing and sight. They can locate their prey in near darkness because one ear, like those of other owls, is higher than the other (asymmetrical) and can be used to determine the location of their prey. Great Horned Owls generally perch in trees or other structures during the day. They can land on the ground but don't usually, because they are clumsy walkers. Great Horned Owls are very territorial and defend their territory year-round.

The usual call of the Great Horned Owl is a series of low hoots that carry great distances. They also make a variety of screeches and clicking noises.

Ecosystem roles:
Great Horned Owls are important predators of small mammals, such as rabbits and rodents. So they can be very important because they can control the amount of pests that may carry disease or ruin plants.

Conservation:
Great Horned Owls are still relatively common in New Mexico, but all raptor populations have been affected by earlier hunting.

• The “ears” of the Great Horned Owl are just tufts of feathers and not ears at all. The owl's ears are located on the side of the head and covered by feathers; there is no external sign of the ears. The ear tufts may help the owl to look bigger to opponents.

Taxonomy:

Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Aves, Birds
Order: Strigiformes, Owls
Family: Strigidae, True Owls
Genus: Bubo, Eagle-Owls
Species: Bubo virginianus, Great Horned Owl, Búho cornudo