They are distributed throughout most of North and very spottily in Central America and then down into South America south to upland regions of Argentina, Bolivia and Peru, before they give way to the Magellanic horned owl, which thence ranges all the way to Tierra del Fuego, the southern tip of the continent. Bird-Banding, 42:103-105. ), are sometimes taken as prey. In some big females, the gripping power of the great horned owl may be comparable to much larger raptor species such as the golden eagle. Tomazzoni, A. C., Pedó, E., & Hartz, S. M. (2004).  Pleistocene era fossils have been found of Bubo owls in North America, which may either be distinct species or paleosubspecies, from as far east as Georgia, but predominantly in the Rocky Mountains and to the west of them.  Effective maximum hunting distance of an owl from an elevated perch is 90 m (300 ft).  On Protection Island, Washington, where they are no native land mammals, rhinoceros auklets (Cerorhinca monocerata), both adults and nestlings, were the most numerous prey, present in 93% of 120 pellets. However, the young are not usually competent fliers until they are about 10 to 12 weeks old. 1972. Of these, the great horned owl and golden eagle were able to nest most closely to one another because they had the most strongly dissimilar periods of activity. wolves (Canis lupus), cougars (Puma concolor) and bears (Ursus ssp.)). , Most tree nests used by great horned owls are constructed by other animals, often from a height of about 4.5 to 22 m (15 to 72 ft) off the ground. Great Horned Owl (, Rohner, C., and F. I. Doyle (1992). All studies have found raptors are a small portion of this owl's diet but predation can be seriously detrimental for such prey, as raptors tend to be territorial and sparsely distributed as a rule and thus can be effectively decimated by a small number of losses.  However, some snakes are partially or largely nocturnal, and more than a dozen species are hunted in North America.  Its size can vary considerably across its range, with populations in interior Alaska and Ontario being largest and populations in California and Texas being smallest, though those from the Yucatán Peninsula and Baja California appear to be even smaller. While the true nature/purpose of the ear tufts that are present on the great horned owl is unknown, researchers agree that the tufts do not play any role in the hearing ability of the owl. The snowy may be the one North American owl too formidable for the great horned owl to consider as prey. Two hare species, the black-tailed jackrabbit and snowshoe hare, are so important to the owls as a food source that the local owl populations sharply rise and fall in sync with the hares' cyclical population trends.  In one single nest, the remains of 57 striped skunks were found. There has been some evidence to support that if prey availability is low enough that the species may forgo mating entirely for a season. , Prey can vary greatly based on opportunity. Occasionally, these owls may prey on threatened species. Even tropical great horned owls have feathered legs and feet. , The breeding habitat of the great horned owl extends high into the subarctic of North America, where they are found up to the northwestern and southern Mackenzie Mountains, Keewatin, Ontario, northern Manitoba, Fort Chimo in Ungava, Okak, Newfoundland and Labrador, Anticosti Island and Prince Edward Island. The feathers on the feet of the great horned owl are the second-longest known in any owl (after the snowy owl). Woolfenden, Glen E. and John W. Fitzpatrick. ", "Bird Master Database Search- Bubo virginianus", "Stacey O'Brien : Wesley the Owl: Crows and Ravens: The Corvids and their odd behavior", "Blakeman answers questions about nest maintenance", "Chihuahua survives owl attack in Illinois", "Comparing the diet of Great Horned Owls (, "Food niche overlap in co-existing Barn Owl Tyto alba (Scopoli 1769) and Great Horned Owl Bubo virginianus Gmelin 1788 in intensively used farmland", "Raptor Presence Along an Urban–Wildland Gradient: Influences of Prey Abundance and Land Cover", "Urban effects on native avifauna: a review", "Presence and Food Preferences of the Great Horned Owl in the Urban Parks of Seattle", "Poisoning of Wildlife with Anticoagulant Rodenticides in New York", "These Owl Chicks Have Two Moms and a Dad—a First", "Great Horned Owl Nest – Interesting Facts & Information", "Nest Site Selection by Urban and Rural Great Horned Owls in the Northeast (Selección del Lugar de Anidamiento por Parte de Bubo Virginianus en Zonas Urbanas y Rurales del Nordeste de los Estados Unidos)", "Nesting of Red-Tailed Hawks and Great Horned Owls in a Central New York Urban/Suburban Area (Anidamiento de Buteo jamaicensis y de Bubo virginianus en un area urbana/suburbana de la parte central de New York", "Early breeding records and nesting phenology of Great Horned Owls in Wisconsin", "January initiation of suburban great horned owl nests in Manitoba", "Interesting Facts About Great Horned Owls", "Composição da avifauna em oito áreas úmidas da Bacia Hidrográfica do Lago Guaíba, Rio Grande do Sul", "Forty-Second Supplement to the AOU Checklist of North American Birds", 10.1642/0004-8038(2000)117[0847:FSSTTA]2.0.CO;2, 10.1674/0003-0031(2002)148[0198:TTOTSG]2.0.CO;2, Bulletin of the British Ornithologists' Club, "A Preliminary Survey of Trends in Avian Evolution From Pleistocene to Recent Time", "Spotted owls, great horned owls, and forest fragmentation in the central Oregon Cascades.  The smallest avian prey known for great horned owls are the 5.8 g (0.20 oz) blue-grey gnatcatcher (Polioptila caerulea) and the 6.2 g (0.22 oz) ruby-crowned kinglet (Regulus calendula). Strix virginiana Gmelin, 1788  In the Upper Midwest, the ring-necked pheasant (Phasianus colchicus) and northern bobwhite (Colinus virginianus) were the fifth and sixth (out of 124 identified species) most significant prey species in 4838 pellets.  In the boreal forest, especially in years where the snowshoe hare experiences population decreases, great horned owls prey fairly heavily (approximately 25% of biomass) on ruffed grouse (Bonasa umbellus) and spruce grouse (Falcipennis canadensis), enough so in the earlier bird to possibly contribute to population reductions.