The great horned owl (Bubo virginianus) is resident almost all over North America, and through much of South America too. These supreme hunters stalk through the night sky on silent wings, often in our very neighborhoods. Their presence becomes known in the winter, however, when pairs begin their rhythmic hooting duets at night.
Great horned owls nest in the cold winter months. They are pretty lazy when it comes to nest building, preferring to use a nest built by other large birds. They make up for this by being great parents, occasionally providing their young with food many months after they have left the nest.
If you’d like to discover more about the breeding habits of one of America’s most impressive birds, you’ve come to the right place, so read on to learn everything you need to know.
|Key Great Horned Owl Nesting Facts|
|Nesting season||February to April, but varies across the range|
|Nesting material||Use existing nests of sticks and twigs|
|Nest type||Platform style nest|
|Number of broods||One brood|
|Clutch size||2 eggs, but ranges from 1 - 4|
|Egg color||Dull white|
|Egg size||56 x 47 mm|
|Egg weight||51 g|
|Incubation period||30 - 37 days, by the female|
|Fledgling period||6 - 7 weeks after hatching|
|Use nest boxes||Open-topped nesting platform|
Great Horned Owl nesting high up in a tree
Great horned owls nest just about anywhere. Nest sites vary tremendously, although the nests of other large birds are most frequently used. These nests are most often located at the tops of large deciduous trees like aspens and poplars, although this does vary geographically.
Great horned owls do not build their own nests, and if an existing nest in a tree is not available, they will even nest on ledges and cliffs, in and on buildings, or even just on the ground.
Before we judge them too harshly, consider the great success of these wise old owls! Read on to learn more about where, how, and when these magnificent birds nest.
Great Horned Owl sitting on her nest inside a tree hollow
Describing the nest of the great horned owl is perhaps more difficult than for any other North American bird species. This is because they use such a wide variety of nest sites!
Some of the most common nests used by great horned owls are those originally built by other large birds. The nest of the widespread and common red-tailed hawk (Buteo jamaicensis) is the most often used, but other hawks, corvids, and even herons also build suitable nests.
The nests used by great horned owls are typically large platform nests constructed from sticks and twigs. Red-tailed hawk nests, for example, are often rather untidy in appearance and can be over six feet deep and three feet across.
It is worth taking a careful look at any such nests you see in the winter months. You might just spot the two ear tufts of a female great horned owl, dutifully incubating her eggs in the crisp winter air!
Great Horned Owl nesting in an old Bald Eagle nest
Great horned owls nest in winter in the United States. The exact timing varies geographically, with birds in the southern states beginning as early as November, but as late as May in parts of Canada.
You might be wondering why the great horned owl would choose to nest in the harsh winter months.
Great horned owl chicks mature slowly, and they spend the first few months of their life learning how to hunt in the vicinity of their parents. Breeding in winter allows great horned owls to care for their eggs and hatchlings during the harshest times of the year, which sets the youngsters up nicely to learn how to fend for themselves during the plentiful days of spring and summer.
A mother Great Horned Owl feeding one of her chicks in the nest, high up in an oak tree
The period from nest site selection to fledging typically lasts about 10 weeks for great horned owls. The female alone incubates the eggs for a period of 30-37 days, but she is fed by her partner during this time.
Once the eggs have hatched, she will brood the chicks continuously for the next two weeks or so. The attentive male will continue to bring food for the female and the chicks during this time. She will only hunt if the male is struggling to provide enough food.
Great horned owls don’t construct their own nests. They prefer to use nests that have already been built by other large birds, although they will use other convenient spots like cliff ledges and large tree cavities where suitable nests are not available.
Great horned owls will often make some effort to make the nest site a little cozier, however. They do this by lining the interior of the nest site with soft materials like feathers from their own bodies or from their prey, fur, and soft plant material like leaves. This isn’t always the case, however, and in some areas, they tend to leave the nest site unimproved.
Young Great Horned Owlets peeking out from the nest
Baby great horned owls first leave the nest at an age of about six weeks. Great horned owls exhibit great parental care and will continue to care for their young long after they have fledged. The youngsters don’t go far at first, remaining in the vicinity of the nest site for several weeks.
One study found that until the age of about 15 weeks, the fledglings had not moved further than a kilometer from the nest site. Baby great horned owls will stay in the vicinity of their parents right up until the fall, and might be fed by their parents for as long as four months after leaving the nest!
Great horned owls usually have a single brood in a season. If the eggs are broken, or nesting fails due to predation, the pair might attempt a second brood.
Great Horned Owl in the nest with two chicks (owlets)
Great horned owls might use the same nesting site year after year if it does not deteriorate too much. Most nests that are adopted from other birds do not last more than a single season but sometimes they will hold up for several years. This depends, in part, on where and how the nest was built, with some nests lasting up to a decade.
Great horned owls are monogamous and can live for over 30 years. A pair can stay together for 5 years or more, and use a nest site in a cavity or on a cliff several times.
Great horned owl eggs are very round as far as eggs go. Most clutches consist of two eggs, but anything from one to four is typical. They are plain white in color and measure about 5.6cm at their tallest and 4.7cm at their widest. They weigh a little over 50g each, which is similar to a standard medium chickens egg.
Great Horned Owl in nest
Great horned owls lay their eggs at different times of the year depending on their location. Birds in warm areas like Florida can begin egg-laying as early as November and December while birds in the cold north may start as late mid-spring.
Interestingly, the timing can also vary on a much smaller scale. Pairs in urban areas can begin egg-laying a month or more before their out-of-town neighbors. During years when prey is abundant and weather conditions are mild, great horned owls can also begin nesting as much as a month earlier than usual.
Great horned owls are more likely to nest on an open-topped nesting platform than in a cavity-style nest box.
A Great horned owl nesting in a cactus in the desert, Arizona
Great horned owls have adapted very well to urban and suburban development. They certainly do nest in backyards where suitable nest sites occur.
This is great news for bird lovers, especially if you have a large yard with good owl habitat. Yards with tall trees (particularly trees that already have large nests in them) are most likely to attract nesting great horned owls.
Great horned owls use the same nest site both day and night for the duration of the incubation and brooding period. They are nocturnal birds that are active at night and roost during the day. Great horned owls usually spend the day resting in trees or rocky areas, but they will occasionally hunt in the daylight hours.
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