The hoots come through the patio doors, the windows, even the walls. Low and soft.

Two great horned owls are talking to each other on this January night.

Courtship started in December when the male owl began hooting on a regular basis.

His mate would join him in conversation only for the several days before the relationship was to be consummated.

Given this night's hoo-hooing, that would seem imminent.

These owls are in the trees on the far side of the wooded swamp that wades into our yard. They're maybe 150 to 200 yards away. If these were songbirds, we would not hear them, even with doors and windows open.

Strong, and deep in pitch, owl voices travel well. Low goes farther. You could say that high frequencies, songs of warblers for instance, get poor mileage.

This works well for the owls because they have large territories, and communication is often long-distance.

The calls this night eventually will bring the two birds together. They will finish courtship with a head-bobbing ritual that can include bill rubbing and mutual grooming.

They will put their eggs and raise their young in a nest they have confiscated. They don't build. They often use nests of red-tailed hawks. The hawks might like to move in again, but the owls get there three months sooner.

Great horned owls are fierce predators. They will capture, kill and eat almost anything alive as long as it's no larger than a raccoon. (This includes domestic cats.)

The owls often share territory with red-tailed hawks. Both hunt much the same prey, the hawk from a hover, the owl from a perch. For their prey animals, hunting has a day shift and a night shift.

If there is no available hawk nest, the nests of crows, ravens, herons or even squirrels will do. Snags and tree cavities are used. The birds will nest in caves, on cliffs, in abandoned quarries, sometimes on platforms or even on the ground.

It depends on where they are, and they are everywhere. Their range stretches from tree line in the north to South America. The owls avoid only high elevation and bare desert.

This species can live into its 20s. The oldest known great horned owl lived 28 years after its banding date, its age at that time unknown.

Two chicks will hatch after a month of incubation. The female has that responsibility. She doesn't leave the nest, her mate bringing her food. Owl chicks are altricial — featherless, blind, helpless. (The opposite is precocial, mobile hours after hatching, like ducks and chickens, for example.)

The young birds will look like and begin to behave as adults in about five months. Here, that's close to the end of June. They will maintain loose association with their parents.

The owls nest in the middle of winter to give young birds time to hone hunting skills. They need to be independent come winter.

They will be floaters for their first year, hanging around the edges of other owl territories. At two years old, the birds will begin to look for a mate. And just after Christmas, like a late present, you might hear them calling in your neighborhood.

They are most active vocally just after sunset and before sunrise. The male will have the deeper, more mellow voice; the female voice is a bit higher.

Three to six notes — hoo-hoo hoo hoo-hoo.

And you needn't even open the window.

Read Jim Williams' birding blog at startribune.com/wingnut.