I am a light sleeper. I was awakened before dawn the other day by a pair of Great Horned Owls (Bubo virginianus) serenading in a large spruce tree outside my window. The male’s deep, resonant but soft “whoo who-who-who whoooooo whoooooo” was immediately followed by the female’s slightly higher call, and they continued back and forth. It’s courting time for this species and now is a good time to hear them. You might need to wake early though as they seem to be most vocal between 3 and 6 am—although I have also heard them at dusk along the Farmington Canal Trail in Hamden.
Male Great Horned Owls set up territories in October. During courtship and before mating, the male will display in front of the female and bring her food. These owls are usually monogamous and often mate for life. After raising young, however, the pair may roost separately until the following winter although still in the same territory.
The pair won’t build their own nest from scratch. Here in New England these owls will commonly use old nests made by Red-tailed Hawks (Buteo jamaicensis), American Crows (Corvus brachyrhynchos), and even Eastern Gray Squirrels (Sciurus carolinensis). Females usually do the incubating. In Connecticut, a female Great Horned Owl sits on two to five eggs for 28 to 35 days, as early as late January to early February. Research has shown that females can successfully incubate eggs even when temperatures hit –27 °F (–32.8 °C)!
Why nest in the cold depths of winter, which seems to be such a hardship? The Great Horned Owl is such a large bird that nesting early gives it a head start on lots of food for growing owlets in early spring right when prey is more active. It also gives young enough time to learn to hunt before the next winter.
This nocturnal owl is such an efficient predator that it is called “the tiger of the skies.” With adaptations like fringed feathers on its primaries, a wing span up to five feet (1.5 meters), extremely strong talons, incredible hearing, and large eyes with sharp vision in low light, it can fly almost silently and dive down on prey. Its eyes are among the largest of all terrestrial vertebrates, about the size of those of humans. They feed on a wide variety of prey, including small mammals such as rodents, hares, and rabbits, other owls, waterfowl, and marsh birds. And they are one of the few predators of the Striped Skunk (Mephitis mephitis).
The name “Great Horned Owl” is a misnomer. They don’t have horns. What they do have are actually large feather tufts. These feathers can indicate their disposition. When the Great Horned Owl roosts during the day, the tufts are often in a narrow, elongated position with upright feathers, a camouflage adaptation that looks like a branch. This might keep the owl from being detected by crows. Crows mob owls, as owls have been known to eat crows. When I see a murder of crows flying quickly in circles and calling excitedly with harsh “caws,” I know they’ve found a predator, usually a hawk or owl.
Great Horned Owls are found throughout North America, from the subarctic in Canada and Alaska down to Mexico. They are highly adaptable to a variety of habitats, from deciduous, coniferous, and mixed forest, to prairies, mountainous areas, rocky coasts, and mangrove swamp forests, to urban areas. If you’re lucky enough to hear them at this time of year, you’ll know they are likely courting. When much of the natural world around us seems dormant, it’s pleasant to think of new life poised to begin anew.