Great Horned Owl (Bubo virginianus)
Habitat
Great horned owls occupy a greater variety of habitats than any other owl in North America. They are birds of coniferous, deciduous and mixed forests, desert, swamp, woodland, prairies, farmland and large urban parks. They prefer areas with open areas for hunting and at least a few scattered trees for perching.
Physical Characteristics
Great horned owls are large dark gray-brown owls with distinct feathered “ear tufts” and large yellow eyes. They have a buff facial disc outlined in black and a distinct white patch on the throat. The breast is tawny with many tiny dark bars; the back is darker and mottled. They average 22 inches (55 cm) in length with a wingspan of about 45 inches (113 cm). Weight typically ranges from 2.5 to 4.5 pounds (1.1-2.0 kg). As with most owls the females are larger than the males but otherwise they are similar in appearance.
Life Span
Great horned owls have lived more than 35 years in captivity.
Diet
In the wild: Great horned owls eat an extremely wide variety of prey. Over 250 prey species have been identified, far more than any other bird in North America. Small mammals such as jackrabbits, cottontails, skunks, meadow voles and mice make up the majority of the great horned owls diet but they will also eat insects, reptiles and birds up to the size of geese and herons.
At the zoo: Mice, rats and coturnix quail.
Reproduction
Great horned owls are one of the earliest nesting birds. Pairs may begin roosting together in early December and females may begin incubating eggs as early as late February. One to six eggs are laid in an old crow or red-tailed hawk nest, tree or cactus crotch, or cavity. Females perform all incubating and brooding duties while their mate supplies them with food. Young hatch at 28 to 35 days and remain in the nest vicinity for 10 to 12 weeks.
Life Cycle
Young owls grow quickly and by 6 to 7 weeks the nest becomes crowded. The young birds soon leave the nest and move onto surrounding branches where they hide and wait for food. These “branching” young begin testing their wings at 6 to 7 weeks. At 9 to 10 weeks the young owls begin to fly and within a few more weeks the young birds will start to fend for themselves. They will remain dependent on the adults for some time while they acquire and hone their hunting skills and will finally disperse from the home range of the adults in the fall.
Calls of the Wild
Great horned owls are fairly sedentary birds and are a common year-round residence throughout much of their range. They maintain their territory for much of the year. The territorial song of the male is a series of four to five deep hoots, Hoo, hoo-oo, hoo, hoo.” The female responds with six to eight hoots, “Hoo, hoo-hoo-hoo, hooo-oo, hoo-oo.” Mated pairs hoot back and forth in a duet. Although soft, their call is booming and far-reaching, and will often send small birds and mammals in search of cover. Great horned owls will drive all other owls from their territory and their presence will also influence the distribution of diurnal raptors, such as red-tailed hawks, which compete with great horned owls for prey.
Location at the Zoo
A great horn owl can be seen at the zoo’s Raptor Center. Other birds of prey that can be viewed at the Raptor Center include the bald eagle, Harris’s hawk, gyrfalcon, turkey vulture as well as spectacled and barred owls. Additionally, owls can be seen in the zoo’s Temperate Forest bioclimatic zone; a spotted or great gray owl adjacent to Bug World and a barn owl at the Family Farm. The Raptor Center’s Eagle Release Program has rehabilitated and released back into the wild more than 80 eagles, plus numerous other raptor species.
Conservation Connection
Due to their adaptability to a variety of habitat types and prey species, great horned owls have remained common, despite continuing persecution over much of their range. Habitat destruction, road fatalities and indiscriminate shooting remain a concern for great horned owl populations in many areas.
Humans need raptors. Here are only a few of the benefits raptors provide:
- Raptors help keep animal populations in balance.
- Raptors consume many animals that humans consider as pests, including mice, rats and destructive species of insects. This helps to control disease and damage to crops.
- As top predators of their food chain, raptors are an indicator species of the overall health of the ecosystem in which they live.
- Of equal importance, witnessing wild raptors enriches each of our lives. Imagine what life would be like if we could no longer gaze upon the grandeur of raptors soaring high above.
How You Can Help!
Efforts to save threatened and endangered raptors require cooperation and support at international, national, regional and individual levels. You can help in this cause. Join and become active in Woodland Park Zoo and other conservation organizations of your choice. Recycle forest products. Eliminate or reduce pesticide use. Support breeding programs for endangered birds of prey at zoos and other animal care organizations. Let your elected representatives know your views about the conservation of migratory birds and their wild habitats.
Contact Woodland Park Zoo at webkeeper@zoo.org to find ways you can support conservation programs at the zoo. Learn other ways you can help conserve wildlife and their habitats by visiting our How You Can Help page.
Sources and Suggested Reading
Hume, Rob. 1997. Owls of the World. Parkgate Books LTD., London. 192 p.
Johnsgard, Paul A. 1988. North American Owls, Biology and Natural History. Smithsonian Institution Press, Washington DC. 295 p.Sutton, Patricia and Clay. 1994. How to Spot an Owl. Charters Publishing Ltd., Shelburne, VT. 143 p.
For Kids!
Jarvis, Kila and Denver W. Holt. 1996. Owls: Whoo Are They? Mountain Press Publishing Company, Missoula, MT. 59 p.
Zoobooks. 1992. Owls. Wildlife Education, Ltd., San Diego, CA. 17 p.