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Great Horned Owl

(Bubo virginianus)

Great Horned OwlThe Great Horned Owl is one of the larger owls in North America.  The Great Horned Owl average size is 22 inches long with a wingspan of about 3 feet.  The “horns” are only tufts of feathers.  They are brown with some spotted coloration in darker shades of brown.

The Great Horned Owl mates in Late January or early February laying 2-3 eggs once a year.  The eggs are incubated by both parents and hatch in about four weeks.  The owls mature quickly.

This owl is found across North America in valleys, grasslands, woodlands, forests and city parks.  Here in the Hampton Roads area it is found everywhere.

They eat mainly squirrels, rabbits, small mammals and other birds but are not limited to that diet.  They swallow their food whole and later regurgitate what their body cannot process in owl pellets.  They have excellent hearing and fly silently through the air that aids in hunting nocturnally.  They will swoop down to catch their prey with powerful feet and talons.

Territories. The territory for a mated pairs may range 1/3 of a mile to 2-5 square miles. Some ornithologists (scientists who study birds) believe that owls form permanent pair-bonds. If one; after the courtship displays end, the male continues to hoot to maintain territory and the female remains near the selected nest until time to lay the eggs. She lays them in the debris (wood chips or other plant matter) in the bottom of the nest. The number of eggs laid seems to be linked to available food supplies. Normally the female lays 2-3 dull white, thick-shelled, oval-shaped eggs. Owls lay only one clutch of eggs per season. Some females nest only every other year. Females in prime habitat may nest every year.
Incubation of the eggs lasts through the winter. Both the females and the eggs can survive extremely cold weather. Incubation usually takes 26-35 days with both sexes sharing in the process. The male feeds the female during this time.
Once the owlets hatch, the male brings large quantities of food to the nest. Prey is stored in the nest, since young owlets will eat their nest mates if not kept constantly fed.
Newly hatched owls are covered with white natal (birth) down. Their eyes open at 9 days and function poorly for the first 2 weeks after opening. The owlet cannot hold up its head. After 3 weeks buff-colored, mottled looking down replaces the natal down. The owlets need constant brooding (female sits on nest and covers owlets) to protect them from cold and predators. A female owl will viciously attack both animal and human invaders during this time.

Great Horned OwlOwlets begin growing their primary feathers (main, adult feathers) at 3 weeks of age. They have light yellow eyes with blue pupils. Less brooding is necessary and they are very active about the nest. Owlets learn to eject excrement (body waste) over the side of the nest but sometimes fall due to their clumsiness. About this time the owlets begin using a defensive display when disturbed. They raise their feathers, fan their wings downward, and hiss or snap their bill.
After 5-6 weeks, the female coaxes the owlets out of the nest by offering food from a nearby branch. At about 9-10 weeks old the owlets first flight out of the nest to the ground.  They quickly scramble up a tree to get away from ground level predators. If approached by a predator, they assume a hiding pose by sitting still and erect against the side of the tree. If this pose fails they present the defensive display.
Feedings become irregular but the young owlets remain with the female and beg for food until September or October. During mid-June, the young owlets use their inborn instinct to attack prey. Young owls leave their parent's home range in autumn, when they are fully independent and can find their own hunting territory.
When a member of the pair dies, the survivor remains in the home territory until another mate arrives.
Owls defend their territories from other owls. Defense occurs during breeding times. It lasts from 1 month before breeding until the young owlets leave the parental territory. Adults may wander across territory lines for a short time before the next breeding season begins. They frequently allow other types of birds such as hawks to live in their territory.
Owls with large territories frequently spend each season in a different part of their territory. Owls use specific areas of their territory for nesting and roosting. Some birds use certain trees so regularly that observers can predict in which trees they will find the owl in during a specific season.
During the winter and fall, owls prefer evergreen roost trees since they provide daytime cover. When these are not available, owls will adapt to any place that provides as much concealment as possible during daylight hours. They seem to prefer to roost in isolated trees in small forest openings.

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