That hoot-hoot-hoot you heard at night or just before dawn in January is the mating call of the great horned owl. After mating, the owls will continue to hoot to stake out a territory and warn other owls away.
Owls breed in the winter because it takes a long time to raise a young owl. First, the female owl takes two to three days to lay, on average, two eggs. Then, she sits on them for 30-35 days.
After hatching, the young birds will remain in the nest for close to two months before their first flight, called fledging. That can be mid to late May or later.
Afterward, the young have to be taught and practice to hunt at night. It can take as long as six months after hatching before the young have their first winter plumage and are good fliers and hunters.
Although most of the great horned owl’s activities take place from sunset to sunrise, they have keen vision day or night. They also have superb hearing.
A facial disc funnels sounds to ear openings covered by feathers on the side of the owl’s head. Their ears are lopsided, allowing them to triangulate sounds and find a mouse scurrying under several inches of snow in the dark of night. Remarkable.
— Bruce Auchly
Fish, Wildlife and Parks