Great Horned owls are majestic birds of prey with iconic ‘horns’ that protrude from the tops of their odds. These highly adaptable predators live across most of the Americas, ranging from Alaska and Canada to the subtropical rainforests of Central and South America.
Adult Great Horned owls are elusive enough in their own right, but what about baby Great Horned owls?
Baby Great Horned owls are born altricial, meaning they’re naked and are pretty much immobile in the nest.
Like many baby birds, baby Great Horned owls are extremely vulnerable and can’t thermoregulate, meaning they can’t stay warm themselves. As a result, one of their parents (usually the female) remains at the nest nearly all the time for at least 1 to 2 weeks.
Young Great Horned owl chicks are also blind and can’t open their eyes. Their eyes remain closed for as long as ten days. After 10-days or so, the tiny chicks begin to open their eyes and shuffle around the nest.
Despite their initial diminutive size, the baby owls grow at an astonishing rate, increasing their weight from around 30 to 50g to about 1kg within just 25 to 30 days!
This equates to as much as 30 to 33g (approx. 1 oz) per day. Weight gain slows after 30 to 40 days or so. After around three weeks, Great Horned owl chicks are reasonably alert and mobile within the nest itself.
Three young Great Horned Owl chicks in the nest
Juvenile Great Horned owls are initially covered with a thick layer of white down, which grows on their naked bodies after around a week to 10 days. The iconic ear tufts of the Great Horned owl grow after around three weeks.
After two to three months, the young owls are covered with much of their adult plumage, though this can take a couple more months to develop fully.
Fledging occurs after around six weeks, at which point the chicks will move to a branch and undertake their first flights. The juvenile birds remain with their parents for the remainder of the breeding season and much of summer.
Juveniles are observed begging for food for as long as 4 to 5 months after leaving the nest! Most juvenile Great Horned owls gain independence from their parents sometime in early-to-mid winter (October until January in most studies).
Close up of a juvenile Great Horned Owl
At birth, baby Great Horned owls are small, measuring just a few cm in length. They’re born altricial, which means they’re naked and blind.
Despite being so small at birth, Great Horned owls grow quickly, reaching some 75% of their adult size and weight by fledging.
Baby Great Horned owls weigh around 35g (1.2oz) at birth. The females tend to weigh slightly more than the males. By 25 to 30 days, the young owls weigh around 800g (males) to 1,000g (females). This is approximately 75% of their full adult weight of around 1.4kg.
As we can see, baby Great Horned owls grow astonishingly quickly in their first few weeks alive. However, by the time they fledge, weight gain slows considerably. It takes the young owls many months to grow from their fledgling weight of around 1kg to their adult weight of 1.4kg.
Two young Great Horned Owlets in the nest
Like other baby owls, baby Great Horned owls are called owlets. They’re also more generally known as chicks.
Like other baby birds, at birth, after hatching, Great Horned owls are called hatchlings. While they remain in the nest, they’re called nestlings, and when leaving the nest, they’re called fledglings. After that, they’re called juveniles and, finally, adults.
Baby Great Horned owls are fed solely on meat. The female typically stays with the nestlings while the male hunts.
The female tears food up into small pieces before feeding it to the chicks directly from her bill. Roles do sometimes mix and interchange. Hares, rabbits, voles, and other rodents are some of the most common food items.
Great Horned Owl feeding one of the chicks in the nest
The female mainly feeds the baby Great Horned owls while the male hunts prey for both.
As the nestlings’ food demands increase, the female joins hunting trips. The male and female roles do sometimes interchange, and both the male and female have been observed raising the chicks alone if the other disappears or dies.
Great Horned owls are very rounded, rather than ovular or elliptical like other birds’ eggs. In fact, they’re considered some of the most rounded eggs of any bird. The eggs are a dull white with a rough, coarse outer texture.
Close up of a baby Great Horned Owl
Great Horned owl eggs measure around 55 to 56 x 45 to 47mm. As we can see, the length and width measurements are very similar, which is evident of how rounded the eggs are.
Great Horned owl eggs are incubated for around 30 to 37 days, with an average of approximately 33 days. The eggs tend to hatch at slightly different times, sometimes at intervals of 2 days apart.
Two Great Horned Owl fledglings perched
On average, Great Horned owls are likely to raise two babies (chicks).
Great Horned owls clutches numbers 1 to 4 eggs, rarely 5. Most clutches number just 2 eggs. Of these two eggs, it’s certainly possible that both chicks survive until fledging at least.
Egg-laying varies massively by latitude and region. For example, in Florida, Great Horned owls may rarely lay their eggs as early as November.
In much of the USA, most first clutches are laid from January to February. Contrastingly, in Canada, in Yukon and Saskaketchawan, egg-laying can occur as late as June.
Interestingly, egg-laying times vary depending on the habitat and microclimate. For example, great Horned owls in warmer microclimates or semi-urban areas can lay their eggs up to one 1-month sooner than others.
In Central and South America, egg-laying occurs throughout much of the year and varies from region to region and habitat to habitat.
Overall, Great Horned owls are considered one of the earliest egg-laying birds in North America.
Close up of two Great Horned Owlets
As one of the larger species of owls, Great Horned owls take long-term care of their chicks. Sometimes, juvenile owls are seen begging their parents for food for some 4 to 5 months after fledging.
Young owls don’t become independent from their parents until they can effectively catch larger prey items such as voles and hares.
Baby Great Horned owls can stay with their parents for the best part of 6 to 9 months. This brings them all the way from as early as January and February to as late as October, November, or even later.
Great Horned owls are large birds with slow, patient lifecycles and small brood sizes of just two chicks on average. Therefore, the parents put maximum effort into raising the chicks for the security of their future generations.
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