Great Horned Owl
Zoo Animals
Great Horned Owl
Bubo virginianus
The Great Horned Owl is the largest species of owl found in the Carolinas. This owl and the Barred Owl inhabit most rural areas of the southeast. They both can be quite vocal even in the daytime and are both referred to as “hoot owls” by many people. Although found in many of the same habitats, these two owls are quite different from each other. The great horned owl’s closest relative is the eagle owl (Bubo bubo) of Eurasia. It is a large, powerful, and long-lived owl that is adapted by its anatomy, physiology, and behavior to survive in any climate except the arctic-alpine regions. Equally at home in
desert, grassland, suburban, and forested habitats, the great horned owl has the most extensive range, the widest prey base, and the most variable nesting sites of any
American owl.
The Great Horned Owl has been described by many as a flying tiger, referring to this
creature’s ferocity. T. Gilbert Pearson stated that “The Great Horned Owl is the feathered tiger of the air. Like the striped terror of the jungle, it hunts by night; among birds and small mammals it is all powerful, and its work of destruction is swift and sure.” This is a good summary of one of the most efficient predators, avian or mammalian, inhabiting the Carolinas. Although a ferocious predator, the Great Horned Owl often has to defend itself, usually against man. This species snaps or claps its bill vigorously when angry, distressed, disturbed, stressed, or threatened. This action is created by snapping the upper and lower beak together rapidly to produce a warning or aggressive sound. It is usually associated with nest disturbance, when humans or other potential predators approach a nest or nestlings. Hissing, low screams, rasping, and wing flapping may accompany bill clapping.
The Great Horned Owl is a fairly common species in the Carolinas. Because of its nocturnal habits, few people ever see these hunters of the night, although most people have probably heard the deep “hoo-hoo, hoo-hoo-hoo, hoo, hoo” that is its trademark call. Their call has aptly been described as a staccato morse code. Most calling takes place in late fall and winter during the courtship period. This owl is generally the upland deciduous or pine forest counterpart to the barred owl, which is mostly found in bottomland forest areas. Because of its ability to successfully kill domestic poultry, the great horned owl was often executed. It is now protected by law from persecution, harassment, or killing, as are all birds of prey.
The two prominent ear tufts of feathers, resembling horns, give this owl its common name. In the southern states, the plumage is generally a dark reddish-brown color, heavily streaked or striped over its entire plumage. Subspecies in the western and northern parts of North America have much grayer plumage. Like all other owls, Great Horned Owls have very large eyes. Their glaring eyes are a brilliant yellow that often give this owl a cat-like appearance. The females of this species are 25-30% larger than the males. The Great Horned Owl’s vision like that of other members of its family is truly exceptional. The huge eyes face forward, giving the owl binocular vision and enabling it to pinpoint prey with deadly accuracy. Additionally, the night vision of the owl group is legendary. The auditory sense of owls is also especially keen. Two characteristics that serve to enhance their hearing are the specialized disc feathers, which funnel sound waves into the ear and the large size of the owl ear. Owls have no fleshy, outer ear; but rather their ears are simply very large holes in their skull placed asymmetrically. These three characteristics of the owl's ear enable them to hunt extremely accurately by sound alone. The unique construction of owl feathers enables owls to fly with virtually no sound. This advantage permits undetected approach to sharp-eared prey such as rodents, birds, and even smaller owl species.
Most horned owls including the Great Horned Owl and the much smaller Screech Owl usually prefer hardwood forests or pine forests, but can be found almost anyplace that provides a good food source and adequate protection. They can also be found in residential areas and even in cities if there is an ample supply of food. Although habitat destruction appears to have reduced horned owl numbers, the owls have demonstrated strong resilience to drastic environmental and habitat changes.
Great Horned Owls are opportunistic feeders. They eat almost any animal that crosses their path that they are capable of killing. Their prey ranges from insects to Canadian Geese and everything in between those two sizes including rodents, amphibians, skunks, weasels, and porcupines. They have been known to capture a domestic cat every now and then.
Great Horned Owls are highly territorial. Mated pairs occupy territories year-round and long-term. Males guard the nest site and territory year round while the female may come and go until breeding season. Territories are established and maintained through hooting, with the highest activity occurring just prior to egg laying. Territoriality peaks again in autumn when juveniles are dispersing and attempting to establish their own territories. The male performs most of the territorial defense, but the female will frequently assist her partner in hooting contests with neighbors or intruders, even during incubation. It is believed that territoriality limits the number of breeding pairs as individuals are prevented from establishing a territory and will live a silent existence as a “floater.”
Great Horned Owls are capable of constructing a sufficient nest but are usually more inclined to utilize a red-tailed hawk’s nest and, occasionally, even a bald eagle’s nest. Red-tailed Hawks and Great Horned Owls usually inhabit similar ecosystems and are both found in the same ranges, but breed at different times of the year, which makes borrowing someone else’s nest a bit easier. In the Carolinas, nesting may begin as early as January. The monogamous owl pair will engage in a very vocal courtship before mating and egg laying. A male will approach a female with much bowing and hooting. The male will cock his tail, swell his white bib, and with much bobbing and jerking utters a series of deep reverberating calls that elicits calls from the female. The male and female will then engage in bouts of calling, called duetting, and bowing with wings drooped or cocked at angles to the body. This reproductive behavior, coupled with displays of bill clapping, bill rubbing, and preening of head and neck feathers serves to establish and maintain a pair bond between the male and female owl.
Female Great Horned Owls usually lay two large, oval, white eggs. She assumes the responsibility for the month long incubation period, at which time the male hunts and brings food to her after dark so that she never has to leave the nest. Opossums and raccoons will eat eggs and young owlets so both parents defend the nest vigorously. The newly-hatched owlets are covered with a coat of thick down and are quite weak and helpless for several days. During the first few days, they can barely raise their heads to be fed. Their eyes will open in 7-8 days. Both parents feed the young, with one of them constantly at the nest to defend the owlets and keep them warm. The low temperatures of winter make constant brooding by one of the parents necessary. The hatchlings are fed small mammals and birds, with cottontail rabbits being the preferred food for the owlets. Four to five weeks are required for the nestlings to reach their full adult size, but plumage development is slower. First flight is attempted at around 9 weeks of age.
The Great Horned owl inhabits most of the landmass of the Western Hemisphere. It is found from northern Canada down through southern South America. It is found in all counties of the Carolinas and every state in the United States. It is considered one of the longest-living owls in North America with some wild individuals living into their late teens and early twenties. As the ever-increasing human population continues to destroy habitat at today’s rapid pace, the population of Great Horned Owls is sure to diminish. However, its ecological role as a controller of rodent populations has finally come to be recognized and appreciated. Perhaps this knowledge will help protect the future of the Great Horned Owl.
