Great Horned Owl (Bubo virginianus)
Prepared by Paul Nicholson, February 2022
Adult Great Horned Owl (left) and fledged owlet (right). Photos by Paul Nicholson.
Great Horned Owls are one of seven owl species that can be seen each year in London and elsewhere in Middlesex County. At 55 cm in length, it is a large bird that is even longer than a Red-tailed Hawk, one of our more common raptors.
Adult Great Horned Owls have a bulky look. Their plumage is mostly streaked and brown so the birds are well-camouflaged when perched in a spruce or other tree. While this bird is named for the tufts of feathers on its head, they aren’t the owls’ actual ears. Its ears are hidden under feathers at the side of its head. It is theorized that the tufts enhance Great Horned Owls’ camouflage by breaking up its outline.
The classic vocalization of a Great Horned is a classic hoot hoot.
Listen to the Great Horned Owl call below:
Video about Great Horned Owls by local photographer Mary Lou Roberts.
Images of Great Horned Owl nestlings in south London snapped in 2021 by London bird watcher and bird photographer Mary Lou Roberts were put into a short film that has been widely shared by media and enjoyed by thousands. For the last many years, Great Horned Owls have successfully nested in a willow tree in London’s Gibbons Park.
Great Horned Owls aren’t a migratory species so Londoners are fortunate to host them all year long. This species nests across Middlesex County, often in deciduous, coniferous or mixed forests. They might take over a large nest that was built by another bird. The nest site might be a stick nest, a cavity nest, a snag, or even in an abandoned building. Nesting commences early in the year. Some Great Horneds are even on the nest in January. Pairs of this species mate for life. Active nests are defended aggressively.
Great Horned Owls are voracious. They usually hunt at dusk, at night, or at dawn for mammals, reptiles, fish, and other birds including other owls.
Other species such as American Crows or even Black-capped Chickadees will sometimes band together and mob a Great Horned Owl in an attempt to get it to move on. If you do hear a cacophony of alarmed bird calls, check to see what has unnerved those birds. It might be an owl.
The State of Canada’s Birds 2019 report remarked on the conservation status of birds of prey such as the Great Horned Owl. Birds of prey “have recovered since the indiscriminate use of DDT was banned in Canada and the United States in the 1970s, and in Mexico in the late 1990s.” The authors added that this success with birds of prey “shows us that when we understand the problem and take action together, conservation works.”
Help make London more Great Horned Owl friendly:
When admiring owls with binoculars or a camera, refrain from crowding or harassing the birds. At all times respect the birds and their habitat.
Support the protection of natural habitats such as woodlands that Great Horned Owls need for food, shelter and breeding.
Avoid using rodenticide / rat poison. Learn more
Avoid use of pesticides and reduce your ecological footprint as much as possible.
Retrofit your home windows using bird-friendly materials to prevent bird-window collisions.