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Birds

Great Horned Owl

Description: 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.

Size: Length 46-63.5cm (18-25") Wingspan 91-152cm (36-60") Weight 900-1800g (32-63.5 oz)

Habits: Activity generally begins at dusk, but in some regions, may be seen in late afternoon or early morning. Both sexes may be very aggressive towards intruders when nesting.

Voice: Great Horned Owls have a large repertoire of sounds, ranging from deep booming hoots to shrill shrieks. The male's resonant territorial call "hoo-hoo hoooooo hoo-hoo" can be heard over several miles during a still night. Both sexes hoot, but males have a lower-pitched voice than females. They give a growling "krrooo-oo" or screaming note when attacking intruders. Other sounds include a "whaaa whaaaaaa-a-a-aarrk" from disturbed birds, a catlike "MEEE-OWww", barks, hair-raising shrieks, coos, and beak snapping. Some calls are ventriloquial. Most calling occurs from dusk to about midnight and then again just before dawn.

Hunting & Food: 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. 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 (over 250 identified) are captured, but rabbits and hares are its preferred prey. Mammalian prey includes all coexisting rodents, squirrels, mink, skunks, raccoons, armadillos, porcupines, shrews, moles, muskrats, and bats. They may sometimes take small domestic dogs and cats. 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. A Great Horned Owl is powerful enough to take prey 2 to 3 times heavier than itself.
Pellets are very large, about  7.6 to 10.2 cm (3- 4") long and 3.8 cm (1.5") thick. Pellets are dark greyish-black and compact. Skulls as wide as 3 cm (1.2") are regurgitated whole. Pellets are regurgitated 6 to 10 hours after eating.

Breeding: 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 (1 square mile).

Mortality: A long-lived Owl, captive birds have been known to live 29 to 38 years, and wild Owls up to 13 years. Most mortality is related to man - shootings, traps, road kills and electrocutions. The only natural enemies are other Great Horned Owls and, occasionally, Northern Goshawks during disputes over nest sites. Peregrine Falcons have also been observed attacking Great Horned Owls.

Habitat: Great Horned Owls have adapted to many different places and climates. They occur in habitats from dense forests, deserts and plains to city parks. They have been known to inhabit the same area as the diurnal red-tailed hawk.

Distribution: Great Horned Owls are found throughout North America from the northern treeline and then in Central and South America. They are resident year-round, however, birds living in the northern part of the species' range may migrate south.