Great Horned Owl (Bubo virginianus)

Great Horned Owl

[order] STRIGIFORMES | [family] Strigidae | [latin] Bubo virginianus | [authority] Gmelin, 1788 | [UK] Great Horned Owl | [FR] Grand duc de Virginie | [DE] Virginiauhu | [ES] Buho Americano | [NL] Amerikaanse Oehoe

Subspecies

Monotypic species

Genus

Members of the genus Bubo are the largest of the owls. Heavily built with powerful talons they are recognisable by their size, their prominent ear-tufts, and their eyes that vary in colour from yellow to brown but are frequently vivid orange. The genus, including the Asian fish owls of the genus Ketupa – now believed to be part of Bubo – comprises of 20 species ranging Eurasia, Indonesia, Africa and the Americas. DNA evidence suggests that the Snowy Owls of Nyctea and the fish owls of Scotopelia are also candidates for inclusion in this genus.

Physical charateristics

Great Horned Owls can vary in colour from a reddish brown to a grey or black and white. The underside is a light grey with dark bars and a white band of feathers on the upper breast. They have large, staring yellow-orange eyes, bordered in most races by an orange-buff facial disc. The name is derived from tufts of feathers that appear to be “horns” which are sometimes referred to as “ear tufts” but have nothing to do with hearing at all. The large feet are feathered to the ends of the toes, and the immature birds resemble the adults. Females are 10 to 20% larger than males.

Listen to the sound of Great Horned Owl

[audio:http://www.planetofbirds.com/MASTER/STRIGIFORMES/Strigidae/sounds/Great Horned Owl.mp3]

Copyright remark: Most sounds derived from xeno-canto


wingspan min.: 91 cm wingspan max.: 152 cm
size min.: 46 cm size max.: 63 cm
incubation min.: 26 days incubation max.: 35 days
fledging min.: 63 days fledging max.: 35 days
broods: 1   eggs min.: 2  
      eggs max.: 4  

Range

North America, Latin America : widespread

Habitat

It is present in many habitats, including northern forests, coastal mangrove forests, and mountain and desert areas. It is absent from heavy or primary rainforest or dense cloud forest.

Reproduction

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 utilise the nests of other birds such as the hawk, crow and heron. They may also use squirrel nests, hollows in trees, rocky caves, clumps of witches broom, abandoned buildings, or on 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 only 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 the 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 2.5 square kms

Feeding habits

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 are 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 are carried off and ripped apart at feeding perches or at the nest. Birds are often plucked first, and legs and wing tips discarded. An extremely wide range of prey species (at least 253 identified) are captured, but rabbits and hares are its preferred prey. 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 killed animals.

Video Great Horned Owl

httpv://www.youtube.com/watch?v=g43BpJ3cb8I

copyright: youtube


Conservation

This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The American or Great Horned Owl is, with its two subspecies, the only representative of the Eagle Owl family in the Americas. The Great Horned Owl is a bird of northern, central and southern America, where it ranks amongst the largest owls. In Suriname only found in the Avicennia mangroves in the coastal area. The Great Horned Owl is a large bird whose power almost rivals the slightly larger Eurasian Eagle Owl (Bubo bubo).
A very adaptable bird it exists, in its various races, from almost arctic conditionds in Alaska to southern mangrove swamps; from sea level to 14,000 feet (4,300 m) in the Andes.
It is an aggressive bird which drives all other owls from its territory, and such is their impact on food supply, that when one of these large birds changes its territory, the diurnal raptors in the area also need to shuffle around and rearrange their huunting areas. Only birds like the Turkey Vulture (Cathartes aura), which do not compete with the Great Horned for food, are safe close to its nest area. Where this rule has been breached, the Great Horned has been known to kill a large number of other owls, including Long-eared, Short-eared, Burrowing, and Barn Owls as well as avariety of diurnal raptos including American Kestrels, harriers and several forms of buzzard.
Great Horned Owl status Least Concern

Migration

They are resident year-round, however, birds living in the northern part of the species’ range may migrate south.

Distribution map

Great Horned Owl distribution range map

Leave a Reply