The Great Horned Owl, Bubo virginianus, is one of the most widely distributed and largest owls, native across the Americas. Also known as the ‘hoot owl‘ or ‘tiger owl‘, these birds are admired for their great size and formidable appearance. They are also known for their attribution to lore and mythology across indigenous cultures.
This owl is one of 10 extant species in the genus Bubo, which includes the different species of horned owls, including the Eurasian Eagle Owl and the Snowy Owl. Together, these belong to the family Strigidae in the family Strigiformes. There are many subspecies of Great Horned Owl across their range, but the exact number is still a point of debate. Some accounts have as few as ten, others as many as 20 but the exact number fluctuates as more research identifies those that are truly distinct.
Those that live in the northern, colder latitudes are larger than those that live in the southern USA or below, conforming to the Bergmann’s Rule.
Appearance & Characteristics
The Great Horned Owl is truly a formidable predator. With a wingspan stretching between 3 to 5 feet (91 – 153 cm) and a weight of up to around 2 kilograms for the larger subspecies. This size places them among the larger species of owls, dwarfing many other owl species. It does vary by subspecies and location but even as an average across the subspecies, this places them amongst the largest of their kind, and on a par with other large birds of prey too.
Their plumage is a blend of brown, gray, and white, providing excellent camouflage in their woodland habitats. The feather tufts on their heads, often mistaken for ears or horns, are one of their most distinctive features. The shades of the plumage does vary across the different subspecies. The Northern Great Horned Owl (Bubo virginianus subarcticus) for example has much paler feathers than any of the other subspecies. Also, the South American Great Horned Owl (Bubo virginianus nacurutu) is the only subspecies to have an amber coloured iris, whereas all the rest have yellow eyes.
These owls have exceptional vision, adapted for low-light conditions, and their large eyes are fixed in their sockets, requiring them to turn their entire head to change their field of view. Their vocalizations are varied, including the classic hooting associated with owls, as well as screeches and other sounds used for communication and territorial defence. Their classical ‘signature’ call though, is a low pitched ‘whoo-hoo-o-o, whoo‘, containing several syllables. For the males the pitch remains low and for females it rises toward the end.
Great Horned Owl Subspecies
The number of subspecies for the Great Horned Owl is in constant flux. Some accounts have them as few as 10, and others up to 20. Here are 17 of the documented subspecies, though not all of them have size and weight data available.
|Subspecies||Location||Size (Wing Chord)||Weight|
|B. v. virginianus||Eastern North America||319 – 388 mm (12.6 – 15.3 in)||1 – 2.5 kg|
|B. v. subarcticus||Northern North America||323 – 390 mm (12.7 – 15.4 in)||0.9 – 2.04 kg|
|B. v. saturatus||Pacific Northwest||330 – 400 mm (13 – 15.7 in)||Not Published|
|B. v. pacificus||Southern California||305 – 375 mm (12 – 4.8 in)||0.68 – 1.66 kg|
|B. v. pallescens||Southwestern North America||318 – 381 mm (12.5 – 15 in)||0.72 – 1.55 kg|
|B. v. mayensis||Yucatan Peninsula||297 – 357 mm (11.7 – 14.1 in)||Not Published|
|B. v. elachistus||Central America||305 – 335 mm (12 – 13.2 in)||Not Published|
|B. v. heterocnemis||Northern South America||350 – 390 mm (13.8 – 15 in)||Not Published|
|B. v. nacurutu||South America||Not Published||Not Published|
|B. v. nigrescens||Andes||345 – 382 mm (13.6 – 15.1 in)||Not Published|
|B. v. magellanicus||Southern South America||Not Published||Not Published|
|B. v. varablanca||Costa Rica||Not Published||Not Published|
|B. v. mesembrinus||Southern tip of South America||Not Published||Not Published|
|B. v. deserti||Desert areas of Southwest U.S. and Northern Mexico||Not Published||Not Published|
|B. v. lagophonus||Northern Rocky Mountains, Alaska||Not Published||Not Published|
|B. v. algistus||West Alaska||Not Published||Not Published|
|B. v. pinorum||The Rockies – Texas, New Mexico, Idaho, Arizona, California||350 – 367 mm (13.8 – 14.4 in)||1.25 kg in limited data|
Distribution – Location and Habitat
Great Horned Owls have an extensive range, found throughout North America, limited and sporadic areas of Central America and large parts of South America. They are incredibly adaptable birds, capable of living in all sorts of environments. From dense forests to open prairies, and even in urban settings. Generally, they do prefer areas that offer a mix of open spaces for hunting and dense foliage for roosting and nesting. In some parts of their range they are more picky than others.
Their ability to thrive in diverse habitats, coupled with their intimidating size, has made them one of the most widespread owl species in the Americas.
The Lifestyle & Behaviour
Great Horned Owls are both nocturnal birds and apex predators in their ecosystems. It’s easy to see with these characteristics why they appear in the owl spirit animal lore for many American Indian tribes, as well as other South American cultures too. Often attributed as a guardian of night, wise and strong but also secretive and stealthy. Some even view the owl as a negative animal, the opposite and enemy of the Eagle.
They hunt primarily at night, using their acute sense of hearing and silent flight to locate and ambush prey. During the daylight hours they roost in their favourite secluded spots, often in tall trees or hidden cavities. By their nature, Great Horned Owls are usually solitary and territorial. Once paired up, they maintain large territories and defend them aggressively against intruders. Their behaviour changes during the breeding season, becoming more vocal and visible as they court and raise their young.
Diet & Nutrition
The Great Horned Owl’s diet is impressively diverse, including mammals, birds, and even reptiles and insects. They are capable of taking down prey much larger than themselves, such as hares, skunks, and even other raptors. They do have a preference however, for rodents such as rats and mice, as well as rabbits and hares. These make up the largest part of their diet and are widely available across most of their range.
Populations that live in the northern range – around Alaska and Canada – have fewer prey species available to them, and rely mostly on a few rodent species, like the deer mouse and the snowshoe hare. Southern populations have a wider range of prey species available.
Their hunting strategy involves perching silently in dim and dark light, before swooping down on unsuspecting prey. In a level flight, they can reach up to 40 mph which, with their silent, stealthy movement is fast enough to catch any prey off guard. They kill their catch by crushing them with their powerful feet or by stabbing with their talons. They then swallow their prey whole or in large pieces, later regurgitating the indigestible parts like bones and fur in the form of pellets.
Predators & Threats
Great Horned Owls are top of their food chain and have few natural enemies. As young chicks though, and when still in the egg, they are vulnerable to other large predators, including eagles and other raptors, crows and ravens. Some opportunistic nest raiders such as foxes and raccoons will also take advantage to eat their eggs any chance they get.
Like most large predator species in North America though, human activities such as deforestation and urbanization, pose the biggest ‘indirect threats’ by reducing their natural habitats. They are susceptible to poisoning from pesticides and rodenticides used in agriculture and accumulated in their prey.
The mating season for Great Horned Owls begins with elaborate courtship rituals, including hooting duets, aerial and physical displays. They are known to puff up their throat like a ball, and approach the female to attempt to rub beaks together. They start very early in the season, with courtship generally taking place between October and December, and mates chosen before the end of January.
Once they have paired up, they typically nest in tree cavities, abandoned nests of other large birds, or even on cliff ledges. The male chooses the nesting site and stomps his feet in it repeatedly to attract the female to the site. Once mated, the female lays between 1-6 eggs (usually 2-3), which both parents incubate. The timing of egg laying can differ by a matter of months across their range. Populations in the north, around Canada and the Northern USA can be as late as April or May, whereas in the Southern USA they lay as early as November to December. It varies by sub species too.
Those that live in more tropical climates, around South and Central America, have less well defined reproduction cycles. The dependency on seasonal variations is not the same and as such, there is less pressure on timing for reproduction to take place.
The chicks hatch after about a month (sooner if the weather is great) and are dependent on their parents for food and protection for several weeks. They weight around 34g at birth, and can grow by as much as 33g per day for the first month of their life. The young owls grow very fast, able to start venturing out the nest by the age of around 6 weeks. At week twelve they will usually have fledged but the timing varies depending on the availability of food and climate. They will be almost full size by the time they fledge the nest.
In the wild, Great Horned Owls can live between 20 to 30 years, but in captivity they have been known to live much longer. The oldest known example of the species, was a 50 year old captive female. Their life stages include the juvenile phase, where they learn to hunt and survive independently, followed by the adult phase, where they establish territories and find mates.
Population and Conservation
The Great Horned Owl is not currently considered a species at risk. In their last assessment by the IUCN in 2018, the species was listed collectively as ‘Least Concern’. Their population is stable, thanks to both their adaptability and broad diet. Conservation efforts focus on preserving their natural habitats and mitigating the impacts of pesticides and human interference.
5 Fun Facts for Kids
- Great Horned Owls can rotate their necks up to 270 degrees!
- They don’t have actual horns – those are just long feathers!
- These owls can fly almost silently, thanks to their special feathers.
- They have been known to live in the same area for many years, across generations.
- Great Horned Owls can swim if they need to!