Grett Horned Owl
GREAT HORNED OWL
The great horned owl (Bubo virginianus), also known as the “horned owl,” is in the order Strigiformes, containing the other owls.
SIZE: The great horned owl is among the largest owls in North America with ear feather tufts referred to in its name. Horned owls can stand over two feet (0.6 m) tall and have four to five foot (1.2–1.5-m) wingspans. Female raptors (hawks, eagles, falcons and owls) are larger than the males. The female great horned owl is about 10–20 percent larger than the male. This sexual size dimorphism may allow the female to hunt different
prey in the same territory, thus reducing competition between the pair and increasing the prey species available to them. Other birds of prey also use this strategy. These impressively large and powerful owls weigh two to four pounds (1–2 kg).
COLOR: Great horned owl body feathers are blotched with a variety of browns and tans with some reddish, light-gray and dark bars. The underside is usually lighter gray with dark bars. The feet are feathered to the toes, and the large, black talons are visible and impressive. The great horned owl has large yellow-orange eyes and a facial disc bordered by dark feathers.
SPEED: Horned owls rarely exceed speeds of 50 miles per hour (80 km/hr).
LONGEVITY: Great horned owls have been recorded to live at least 28 years in the wild, while captive birds have been known to live nearly 40 years.
REPRODUCTION: In Alaska, great horned owls will nest in a variety of locations including tree cavities, cliff ledges and old buildings, but they most often use an old nest of another large bird such as a raven, hawk or even a magpie. Great horned owls have an advantage for locating the best nests; they begin their nesting cycle in January and February, which is much earlier than their competitors. Once they have established themselves at a nest, even if it belonged to another large predatory bird, the owls are difficult to dislodge from the site. Courtship includes hooting, bowing to each other with drooped wings, and mutual bill rubbing and preening. The male mounts the female for the quick copulation. Eggs are laid every day or two apart, but incubation begins when the first egg is laid to protect it from freezing. Incubation of the two to five eggs takes about 30 days. The chicks grow quickly and are hopping around the nest site at six to seven weeks old. They fledge at approximately ten weeks of age. After fledging, the young will continue to be fed for several weeks by the adults. The juveniles disperse in the fall. Adults in northern regions usually migrate south during the winter, but many adults remain near their breeding territories. The juveniles disperse widely. The adults may use the same nesting territory for many years. Great horned owls aggressively defend their nests, even from humans. Some great horned owl researchers have scars from the talons of an angry and defensive owl.
SOCIAL STRUCTURE: Great horned owls are notorious for their aggressive behavior. A breeding pair will exclude other horned owls and raptors from their nesting territory. Great horned owls mate for life.
DISTRIBUTION: Great horned owls range from North to South America, wherever there are trees for nesting.
MOVEMENTS AND MIGRATION: Great horned owls are residents throughout the year over most of their range, with the exception of many of the most northern owls which will migrate south during the winter. This is especially true during years of low snowshoe hare abundance.
HABITAT: Horned owls are very adaptable birds. They are found in a variety of habitats, including many cities and towns.
PREY: The great horned owls are also a very adaptable predator, taking a large suite of prey items. Waterfowl and other birds, squirrels, rats, hares, marten and other small mammals are the prey most often caught in Alaska. Domestic pets are also on their menu, especially cats.
PREDATORS: Natural enemies of great horned owls are other great horned owls and northern goshawks. In both cases, this aggression probably is only during nest site disputes.
PREDATORY CHARACTERISTICS: Most owls have soft feathers; many feathers have a leading edge that is serrated. These characteristics allow for silent, stealthy flight. Great horned owls hunt by gliding silently through the forest or over meadows. They also like to hunt from perches, usually old dead trees. These hunting techniques give them the advantage of surprise. Nearly silent flight aids in the element of surprise: most of their prey never knows what hit them. The owl will dive and hit the prey hard with its open feet. The talons pierce through the flesh and into vitals and crush the life out of their victims. Smaller prey is eaten whole or ripped into two or three chunks and swallowed. Birds are plucked before being eaten. Larger prey is taken back to the nest or a perch where it is ripped apart with the strong beak and eaten. Some of the prey can weigh three times that of the owl. Since these animals are too heavy for the owl to carry, they are fed upon near the kill site until the owl is satiated. Great horned owls also will hunt walking on the ground to catch small prey, or wading into the water for frogs and fish.
CURRENT STATUS: Great horned owl populations are healthy in Alaska. Population densities vary, depending upon habitat and prey abundance.
ECOLOGY/CONSERVATION: Understanding the ecology of great horned owls is the job of the scientist, and this often requires study of the owl’s feeding habits. When the owl eats a small vole, bird or mouse whole, the non-digestible fur, feathers and bones are formed into pellets and regurgitated. Researchers collect the pellets and analyze the contents to determine the owl’s prey. Great horned owl pellets are really very interesting to pick through. They can be four inches (10 cm) long and 1½ inch (3.8 cm) thick, and they are usually dark gray to black. If you are lucky enough to find a raptor’s pellet make sure you pick it apart carefully and in the presence of some children. You soon will see that youngsters find this experience worth repeating. Try to figure out what the owl was eating by identifying the bones. The skull and teeth are especially revealing for identifying prey species. Great horned owls eat primarily nocturnal prey and that is what you would expect to be represented in the pellets.
Great horned owls are very territorial, and they will not hesitate to attack intruders. To avoid injury most birds avoid fighting, especially with members of the same species. Owls will hoot to keep other owls out of their territories. If the conditions are right the hooting can be heard miles away. When great-horned owl hooting can be heard, especially during the nesting season, this is a warning that all animals should heed. Owls help maintain a healthy ecosystem by controlling small-mammal population explosions that will result in over-grazing of habitats and the spread of disease.
However, all birds of prey are susceptible to human activities, including poisoning from insecticides and other contaminants, loss of habitat and persecution. Do your part to make the environment safe for great horned owls and other predators, and you will make the world a better place for humans, too.
References:
Wright, Bruce A., 2011. Alaska Predators, Their Ecology and Conservation. Hancock House Publishing. 119 pages. http://www.hancockhouse.com/products/alapre.htm
Other species:
Pacific sleeper sharks in Alaska
Salmon sharks in Alaska
Great white sharks in Alaska
Bald Eagle
Gyrfalcon
Snowy Owl
Black Bears
Brown Bears
Polar Bears
Orcas
Wolves
Wolverine
The great horned owl (Bubo virginianus), also known as the “horned owl,” is in the order Strigiformes, containing the other owls.
SIZE: The great horned owl is among the largest owls in North America with ear feather tufts referred to in its name. Horned owls can stand over two feet (0.6 m) tall and have four to five foot (1.2–1.5-m) wingspans. Female raptors (hawks, eagles, falcons and owls) are larger than the males. The female great horned owl is about 10–20 percent larger than the male. This sexual size dimorphism may allow the female to hunt different
prey in the same territory, thus reducing competition between the pair and increasing the prey species available to them. Other birds of prey also use this strategy. These impressively large and powerful owls weigh two to four pounds (1–2 kg).
COLOR: Great horned owl body feathers are blotched with a variety of browns and tans with some reddish, light-gray and dark bars. The underside is usually lighter gray with dark bars. The feet are feathered to the toes, and the large, black talons are visible and impressive. The great horned owl has large yellow-orange eyes and a facial disc bordered by dark feathers.
SPEED: Horned owls rarely exceed speeds of 50 miles per hour (80 km/hr).
LONGEVITY: Great horned owls have been recorded to live at least 28 years in the wild, while captive birds have been known to live nearly 40 years.
REPRODUCTION: In Alaska, great horned owls will nest in a variety of locations including tree cavities, cliff ledges and old buildings, but they most often use an old nest of another large bird such as a raven, hawk or even a magpie. Great horned owls have an advantage for locating the best nests; they begin their nesting cycle in January and February, which is much earlier than their competitors. Once they have established themselves at a nest, even if it belonged to another large predatory bird, the owls are difficult to dislodge from the site. Courtship includes hooting, bowing to each other with drooped wings, and mutual bill rubbing and preening. The male mounts the female for the quick copulation. Eggs are laid every day or two apart, but incubation begins when the first egg is laid to protect it from freezing. Incubation of the two to five eggs takes about 30 days. The chicks grow quickly and are hopping around the nest site at six to seven weeks old. They fledge at approximately ten weeks of age. After fledging, the young will continue to be fed for several weeks by the adults. The juveniles disperse in the fall. Adults in northern regions usually migrate south during the winter, but many adults remain near their breeding territories. The juveniles disperse widely. The adults may use the same nesting territory for many years. Great horned owls aggressively defend their nests, even from humans. Some great horned owl researchers have scars from the talons of an angry and defensive owl.
SOCIAL STRUCTURE: Great horned owls are notorious for their aggressive behavior. A breeding pair will exclude other horned owls and raptors from their nesting territory. Great horned owls mate for life.
DISTRIBUTION: Great horned owls range from North to South America, wherever there are trees for nesting.
MOVEMENTS AND MIGRATION: Great horned owls are residents throughout the year over most of their range, with the exception of many of the most northern owls which will migrate south during the winter. This is especially true during years of low snowshoe hare abundance.
HABITAT: Horned owls are very adaptable birds. They are found in a variety of habitats, including many cities and towns.
PREY: The great horned owls are also a very adaptable predator, taking a large suite of prey items. Waterfowl and other birds, squirrels, rats, hares, marten and other small mammals are the prey most often caught in Alaska. Domestic pets are also on their menu, especially cats.
PREDATORS: Natural enemies of great horned owls are other great horned owls and northern goshawks. In both cases, this aggression probably is only during nest site disputes.
PREDATORY CHARACTERISTICS: Most owls have soft feathers; many feathers have a leading edge that is serrated. These characteristics allow for silent, stealthy flight. Great horned owls hunt by gliding silently through the forest or over meadows. They also like to hunt from perches, usually old dead trees. These hunting techniques give them the advantage of surprise. Nearly silent flight aids in the element of surprise: most of their prey never knows what hit them. The owl will dive and hit the prey hard with its open feet. The talons pierce through the flesh and into vitals and crush the life out of their victims. Smaller prey is eaten whole or ripped into two or three chunks and swallowed. Birds are plucked before being eaten. Larger prey is taken back to the nest or a perch where it is ripped apart with the strong beak and eaten. Some of the prey can weigh three times that of the owl. Since these animals are too heavy for the owl to carry, they are fed upon near the kill site until the owl is satiated. Great horned owls also will hunt walking on the ground to catch small prey, or wading into the water for frogs and fish.
CURRENT STATUS: Great horned owl populations are healthy in Alaska. Population densities vary, depending upon habitat and prey abundance.
ECOLOGY/CONSERVATION: Understanding the ecology of great horned owls is the job of the scientist, and this often requires study of the owl’s feeding habits. When the owl eats a small vole, bird or mouse whole, the non-digestible fur, feathers and bones are formed into pellets and regurgitated. Researchers collect the pellets and analyze the contents to determine the owl’s prey. Great horned owl pellets are really very interesting to pick through. They can be four inches (10 cm) long and 1½ inch (3.8 cm) thick, and they are usually dark gray to black. If you are lucky enough to find a raptor’s pellet make sure you pick it apart carefully and in the presence of some children. You soon will see that youngsters find this experience worth repeating. Try to figure out what the owl was eating by identifying the bones. The skull and teeth are especially revealing for identifying prey species. Great horned owls eat primarily nocturnal prey and that is what you would expect to be represented in the pellets.
Great horned owls are very territorial, and they will not hesitate to attack intruders. To avoid injury most birds avoid fighting, especially with members of the same species. Owls will hoot to keep other owls out of their territories. If the conditions are right the hooting can be heard miles away. When great-horned owl hooting can be heard, especially during the nesting season, this is a warning that all animals should heed. Owls help maintain a healthy ecosystem by controlling small-mammal population explosions that will result in over-grazing of habitats and the spread of disease.
However, all birds of prey are susceptible to human activities, including poisoning from insecticides and other contaminants, loss of habitat and persecution. Do your part to make the environment safe for great horned owls and other predators, and you will make the world a better place for humans, too.
References:
Wright, Bruce A., 2011. Alaska Predators, Their Ecology and Conservation. Hancock House Publishing. 119 pages. http://www.hancockhouse.com/products/alapre.htm
Other species:
Pacific sleeper sharks in Alaska
Salmon sharks in Alaska
Great white sharks in Alaska
Bald Eagle
Gyrfalcon
Snowy Owl
Black Bears
Brown Bears
Polar Bears
Orcas
Wolves
Wolverine