Area. Western Siberia from the Perm Urals (Cherdyn, where transitional to ruthenus population) and Bashkiria (the same population described by Sushkin as baschkiricus) to the middle Ob (Tomsk) and the western Altai regions, the northern border is not traced, apparently it passes somewhere in the bay. Berezovsky district on the Ob or in the basin of the Taza.
Nature of the stay. The West Siberian Eagle Owl is partially sedentary, but to a large extent roaming bird. This eagle owl makes, more or less regularly, distant migrations. Winter finds in the west to Karelia (Bear Mountain, winter 1937), the upper Mezen basin (Udara river, former Yarensky district, winter 1932), the Bashkir steppes (Birsk, late autumn 1930), the southeastern Caspian (Gassan-Kuli 6.11 .1938), the lower reaches of the Syr Darya (Julek on January 14, and Alma-Ata).
Habitat. Taiga, but not "deaf", willingly near ponds. In the Ural Mountains up to 1000 m (Iremel).
Number. Low - severe conditions of existence, forcing this form to migrate, cause fluctuations in numbers: in the Tyumen region there are many owls in other years (in 1883-1884, especially in 1887), in others there are none at all (Slovtsov, 1892), the same fluctuations abundances are also noted for the Trans-Urals (Ushkov).
Breeding. In the Ilmensky reserve, according to Ushkov, one pair of eagle owls is located at a distance of 4-5-6, on average a little more than 5 km, Nests in niches among stones, on the southern slopes that are more likely to be free of snow, have been used for many years (probably in shifts? ) The beginning of the sexual cycle is very early - already at the beginning of March, when all conditions are winter, you can hear the hooting and "laughter" of owls. There are 2 eggs in the clutch. Dimensions (12) 58.5-62x50-51, an average of 59.43x50.1 mm (Ushkov). In 1937-1941 full masonry on April 9–15 (however, “fresh” masonry for the Tyumen region was also allegedly marked on May 18, Slovtsov, 1892). Hatching occurs from the first egg, chicks are of different ages. Only the female incubates, the male guards the nest and carries her prey, bringing already known stocks before the hatching chicks (in one case, 9 water rats). Hatching was observed on May 15-20, the incubation period is therefore 35 days. Mesoptiles chicks - at the age of 20 days. At 30 days old chicks crawl out of the nest and stay near it, at 50 days they become flying. The first 10 days, the female is always present in the nest and heats the young, and the male brings food.
Nutrition. In summer, the Siberian eagle owl preys mainly around the nesting site, in winter - often near settlements. In the feeding regime of the Siberian eagle owl, vertebrates occupy 98.6%, of which mammals 90.4%. Among mammals, in the first place are mouse-shaped, 83.8%, of which 49.3% are water rats, 51% are field voles, in addition, white and brown hares, squirrel, chipmunk, wood mouse, mole, and young roe deer. 24.1% of birds were found, among them mainly chicken (grouse, black grouse, capercaillie), ducks (crested blacken, teal whistle and cracker, mallard), coot, chomga, black-throated loon, marsh harrier, small buzzard, black kite, marsh owl, turtledove, clintukh, woodcock, gray-headed gull, gray-headed woodpecker, big spotted woodpecker, yellow, cuckoo, of passerines - mainly ravens (Crow, magpie, jackdaw, rook, jay), in addition, finch and thrush, occasionally - insects. In summer, mouse-like rodents occupy a sharply predominant place in the feeding of an eagle owl; in winter, the proportion of birds increases. (Harrow, chicken) and hares. The need for food per day is about 650-670 g (in adults and large chicks). Eagle owls hunt at night, and in winter and in cloudy weather - and during the day. All the above information refers to the Ilmensky reserve and belongs to Ushkov. The relationship between the number of Siberian eagle owl and hares has already been noted.
There are indications of an attack by Siberian eagle owls on poultry (Narym, Ilmensky Reserve).
Description. Dimensions and structure. Large eagle owl with toes clawed to claws. The wing of males (7) 438-465, females (14) 472-515, an average of 451 and 492 mm. The length of the female (1) is 732, the span is 1586 mm.
Coloring. The most light-colored subspecies both in the pale basic tone of plumage and in the weak development of dark speckles. The main color tone is creamy white with a slight admixture of ocher color. The dark pattern is slightly developed, the transverse stripes on the abdomen and sides are usually irregular, thin and far apart, the dark longitudinal stripes on the nape and neck are very narrow, dark spots on the humeral are small and occupy only the very top of the feather, on the humeral and covering wings well large whitish streaks are expressed. With significant individual variability of Siberian eagle owls, they still always have a common whitish tone of plumage color, a very small “blurry” dark pattern and irregular transverse striping of the belly and sides.
Source: Birds of the Soviet Union, t.1. - M .: Owls. the science. 1951.