On average the northern hawk-owl will lay 3–11 eggs per brood. Three to five weeks after hatching, the young leave the nest (Duncan and Duncan, 1998; Nero, 1995). [13][15], In Yukon, northern hawk-owl densities were estimated to be between zero and six pairs per 100 km2 (39 sq mi). [16], In North America, over 50% of the northern hawk-owls' breeding territory occurs in non-commercial boreal forests [3] and as long as nothing threatens their northern habitats, no known factors challenge their existence. The Animal Diversity Web team is excited to announce ADW Pocket Guides! The specific dates of egg appearance can be quite variable depending on locality. Owls: Their Life and Behavior. [3], Occasionally, S. u. caparoch can extend its territory as far south as northern Minnesota and many other states in the northern United States including more central states such as West Virginia, New York, and South Dakota. This species has also spread through northern Russia and Scandinavia (de la Torre, 1990). They hunt primarily during the day, which means that they identify prey by sight and their hearing isn’t as acute as other owl species’. In Eurasia the northern hawk-owl's biomass consists of about 94% microtine voles, whereas in North America the percentage of biomass contributed by voles can be as low as 20%. The northern hawk-owl feeds on a variety of prey, which can include small rodents to mammals more robust in size, and a variety of birds,[8] a typical diet for many boreal owls. When moving from one perch to another, it quickly dives down, stays low, and then abruptly flies up to the new perch. de la Torre, J. At night the Great Horned Owls kill roosting owls while they are resting or enter nests and take eggs or young. The extent to which they prey on birds is unknown. These birds not pose a serious threat to humans. Often referred to as the "earless" owl, they lack true ear tufts; the external ear openings are elliptical (de la Torre, 1990). [3], The northern hawk-owl has been said to resemble a hawk in appearance and in behavior. defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement. The preferred perching tree of the northern hawk-owl is the spruce tree. [14], Populations are known to fluctuate with cycles of small rodents [5][6][15] and irruptions are known to occur in sub-boreal regions throughout the world. the area in which the animal is naturally found, the region in which it is endemic. In the winter, the Northern Hawk Owl sometimes eats ptarmigan and grouse. [5] In 1991, Schmutz and Moker first reported the karyotype of the northern hawk-owl and found it to resemble considerably that of the genus Athene. To avoid predation, the Northern Hawk Owl flattens its plumage and stands erect. Surnia ulula lives primarily in dense coniferous or coniferous-deciduous forests, which adjoin open areas. In particular during the summer months, the Northern Hawk Owl plays a significant role in controlling the rodent population; rodents may make up as much as 90% of their diet (Lockshaw, 2001). (2008) The little owl : Conservation, ecology, and behavior of Athene noctua. These voles usually follow a 3–4 year cycle of abundance. Forestry compromises natural nesting cavities and human encroachment further removes hunting ground. The northern hawk-owl will perch and scour the immediate area for prey. [3] S. u. caparoch can occasionally be found in more southern areas such as Great Britain, southern Russia and Scandinavia, following explosions of prey. young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching.