With their distinctive ear tufts, large, piercing yellow eyes, and low-pitched hooting call, adult great horned owls are one of the most easy-to-identify owl species, as well as one of the largest and most deadly.
Our guide explores what juvenile great horned owls look like at different stages of their development, and investigates how long it takes before a young owl is indistinguishable from an adult bird.
Great horned owl chicks are born featherless and with their eyes closed. A thick layer of white down covers their body by around a week to 10 days.
From between 7 and 21 days, the white down is gradually replaced with longer, grayish feathers that are downy and fluffy in texture. At this stage barred markings emerge and brownish-black facial discs start to appear. The recognizable ear tufts of the great horned owl begin to develop around three weeks after hatching and become more prominent as time passes.
After two to three months, the young juvenile owls are covered with much of their adult plumage, though this can take a couple more months to develop fully, and they retain a softer, fluffier plumage texture which is gradually replaced by the September after they hatch.
Young Great horned owl have slate gray bills when they hatch, which darken in fully mature birds. Their eyes are initially a steely gray or a shade of hazel-yellow; these change to become the bright yellow of an adult’s bird by the time juveniles reach 30 days.
Juvenile Great Horned Owl on the ground
Although they are born featherless, newly hatched great horned owls soon become covered with a fluffy white down in the first week of life. This is then replaced with grayish feathers, and gradually markings of an adult bird begin to develop.
By the time they fledge, juvenile great horned owls are somewhat similar to adult birds, with a gray-white mottled plumage that is barred with darker brown bands. Their plumage offers them an effective camouflage against their woodland habitats, with various shades of brown and black helping them to blend into their surroundings unnoticed.
By the time they reach 30 days, juveniles have developed the same striking yellow irises seen in adult birds. These are surrounded by blackish-brown eye rings, sometimes with a reddish tinge, and a dark facial disk outline.
Recently fledged Great Horned Owlet
During the nestling stage, young great horned owls experience rapid growth, increasing from an average birth weight of 34.7 g (1.2 oz) to 1,000 g (35.3 oz) at 25 days for a female great horned owlet, 800 g (28.2 g) at 29 days for a male. Data from observations of fledgling weight shows that juveniles weigh around 75 percent of the weight of an adult bird by the time they are ready to leave the nest.
Juvenile great horned owls rely on their parents for food and eat whatever is brought back to the nest by the male. Initially this could include insects and worms, but as they grow, young great horned owls will be fed small mammals, reptiles and other birds.
Rabbits, voles, hares, and small rodents are among the most common food items. These prey items are torn into manageable pieces by the female while the owlets are still in the nest.
By the time the young owls fledge but haven’t quite managed to fully get to grips with the art of hunting, parents will continue to bring catches for their young, but will leave them to dissect the items themselves or allow them to experiment with swallowing prey whole.
Three juvenile Great Horned Owlets perched on a branch together
Juvenile and young great horned owls use screeching as a way to communicate they are hungry and this piercing sound can be heard when young owlets beg their parents for food.
Vocal communication begins even before hatching, with young great horned owlets producing weak cries from inside the egg which continue once they are being brooded. With time, their calls become louder and more intense, with different sounds being practiced and incorporated into their range of vocalizations.
Young male great horned owls will spend time in the nest perfecting their hooting, mimicking adult male birds. After considerable practice, by the spring after they hatch they are capable of stronger hoots. Female juvenile great horned owlets do not practice hooting, but in their first spring as mature birds, they are able to hoot fully.
Very young Great Horned Owlet just after fledging the nest
By around three months, young owls have acquired much of their adult plumage, but it is not until several months later that the fluffiness and downy texture have fully been replaced with their full set of feathers.
Great horned owls fledge after around six weeks, but remain on branches close to the hatch site at first. They continue to return to the nest for a few more weeks, gradually mastering further flights and attempts at hunting. Five weeks after fledging, sustained flights of up to 5 minutes can be successfully completed.
Juvenile birds remain with their parents for the remainder of the breeding season, roosting close together and continuing to be fed occasionally, even up to 4 to 5 months after leaving the nest.
By between October and January, most young great horned owls will be fully independent from their parents.
Three Great Horned Owl chicks in the nest with their parent
Juvenile great gray owls look fairly similar to young great horned owls, but lack the distinctive ear tufts, and the great gray owl has a rounder face shape. Eagle owl owlets share similar features and coloring to juvenile great horned owls, with ear tufts, dark barring on lighter brown mottled plumage, and the same piercing yellow eyes.
As with other owl species, one name commonly given to young great horned owl chicks is ‘owlets’.
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