<P> Hunting activity tends to peak between 8: 30 pm and 12: 00 am at night and then can pick back up from 4: 30 am to sunrise . Hunting activity tends to be most prolonged during winter by virtue of prey being more scarce . However, great horned owls can learn to target certain prey during daylight in the afternoon when it is more vulnerable, such as eastern fox squirrels (Sciurus niger) while they're building their leaf nests and chuckawallas (Sauromalus ater) sunning themselves on desert rocks . Owls hunt mainly by watching from a snag, pole or other high perch . During hunting forays, they often fly about 50 to 100 m (160 to 330 ft) from perch to perch, stopping to survey for food at each, until they sense a prey item below . From such vantage points, owls dive down to the ground, often with wings folded, to ambush their prey . Effective maximum hunting distance of an owl from an elevated perch is 90 m (300 ft). Due to their short but broad wings, great horned owls are ideally suited for low speed and maneuverability . Despite reports that they do not hunt on the wing, they also sometimes hunt by flying low over openings on the ground, scanning below for prey activity . Great horned owls can fly at speeds of more than 65 km / h (40 mph) in level flight . Hunting flights are slow, often quartering low above the ground where prey is likely to occur in open country or open woodland . Brief hovering flight (for about 6--18 seconds) have been described, especially in windy areas . On occasion owls may actually walk on the ground in pursuit of small prey or, rarely, inside a chicken coop to prey on the fowl within . Rodents and invertebrates may be caught on foot around the base of bushes, through grassy areas, and near culverts and other human structures in range and farm habitat . The great horned owl is generally a poor walker on the ground; it walks like a starling, with a pronounced side - to - side gait . They have been known to wade into shallow water for aquatic prey, although this has been only rarely reported . Owls can snatch birds and some arboreal mammals directly from tree branches in a glide as well . The stiff feathering of their wings allows owls to produce minimal sound in flight while hunting . </P> <P> Almost all prey are killed by crushing with the owl's feet or by incidentally stabbing of the talons, though some may be bitten about the face as well . Prey is swallowed whole when possible . When prey is swallowed whole, owls regurgitate pellets of bone and other non-digestible bits about 6 to 10 hours later, usually in the same location where the prey was consumed . Great horned owl pellets are dark gray or brown in color and very large, 7.6 to 10.2 cm (3.0 to 4.0 in) long and 3.8 cm (1.5 in) thick, and have been known to contain skulls up to 3 cm (1.2 in) in width inside them . However, not all prey can be swallowed at once, and owls will also fly with prey to a perch and tear off pieces with their bill . Most dietary studies focus on pellets found under perches and around nests, since they provide a more complete picture of the diversity of prey consumed, but prey remains outside of pellets may provide clues to prey excluded from the pellets and a combination of both is recommended . Many large prey items are dismembered . Great horned owls may behead large prey before taking it to its nest or eating perch . The legs may also be removed, as may (in some bird prey) the wings . The great horned owl will also crush the bones of its prey to make it more compact for carrying . On occasion, the owls may return to the kill site to continue eating if the prey is too heavy to fly with after dismemberment . Many owls will accrue a cache of prey, especially those who are nesting . Caches must be at a safe location, usually the crotch of a tall tree . In northern regions, where large prey is prevalent, an owl may let uneaten food freeze and then thaw it out later using its own body heat . Hunting success seems to require fairly open understory, and experimental testing of microhabitat proved that open areas provided more hunting success on five species of rodent, with cloudy nights and denser bush foliage both decreasing success . </P> <P> Prey can vary greatly based on opportunity . According to one author, "Almost any living creature that walks, crawls, flies, or swims, except the large mammals, is the great horned owl's legitimate prey". In fact, the great horned owl has the most diverse prey profile of any raptor in the Americas . Over 500 species have been identified as great horned owl prey, with dozens more identified only to genus or general type (especially numerous invertebrates) and presumably several more unknown from their relatively little - studied populations in the neotropics . Mammals (more than 200 species) and birds (nearly 300 species) make up the majority of their diet . Their diet in North America is made up of 87.6% mammals, 6.1% birds, 1.6% reptiles and amphibians with the remaining 4.7% being made up by insects, other assorted invertebrates and fish . Estimated mass of individual prey for the owls has ranged from as little as 0.4 g (0.014 oz) to as much as 6.8 kg (15 lb) Most prey is the range of 4 g (0.14 oz) (shrews) to 2,300 g (5.1 lb) (jackrabbits). A single owl requires about 50 to 100 g (1.8 to 3.5 oz) of food per day and can subsist on a large kill over several days . Despite the great diversity of prey taken by these predators, in most of the Continental United States from the East to the Midwest as well as Canada and Alaska, great horned owls largely live off just a handful of prey species: three species of lagomorph: the eastern cottontail (Sylvilagus floridanus), the snowshoe hare (Lepus americanus) and the black - tailed jackrabbit (Lepus californicus); two species of New World mice: the white - footed mouse and the North American deermouse (Peromyscus leucopus & maniculatus), approximately three species of vole: the meadow, prairie and woodland voles (Microtus pennsylvanicus, ochrogaster & pinetorum) and one introduced pest, the brown rat . </P> <P> Small rodents form the great majority of great horned owl prey by number . Weighing a mere 14 to 31.5 g (0.49 to 1.11 oz) and 20 to 58 g (0.71 to 2.05 oz) on average, the nine species of New World mice in Peromyscus and eight species voles in Microtus recorded in the diet would appear to be overly small to be as important as they are to a predatory bird of this size . The prominence of these genera is undoubtedly due to the abundance of both genera in the wooded edge habitats frequented by great horned owls . It is estimated that a family of owls with two offspring would need to take about a half dozen (voles) to a dozen (mice) of these rodents every night to satisfy their dietary requirements but apparently the accessibility and abundance of these foods is irresistible as their numeric dominance is indisputable . By winter in areas that hold heavy snow, Peromyscus mice often come to outnumber the voles in the diet since the mice tend to travel over the surface of the snow while the voles make tunnels underneath the snow . In fact, a healthy family of great horned owls can decimate a colony of field rats, thus potentially performing a key role in controlling a highly destructive pest . Great horned owls living in the timbered fringes of garbage or refuse dumps may subsist mostly on rats . </P>

How much weight can a great horned owl lift
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