Background color of adult Eagle Owls is very variable from dark-rusty dense black-brown mottled to pale-buff or almost creamy-white with rare isolated spots. Head is dark streaked above. Feathers of shoulders are with dark tips and marble same-color pattern on base of feathers; its outer webs often are with large white spots which formed character mottling on the back of Eagle-Owl. Wing is broad and short, its tip is formed by 3-5 primaries with dark tips. Borders of outer webs of 1-3 primaries are barbed, second and third primaries are barbed only in narrowed terminal part. Tail is slightly rounded; tail feathers are with very variable cross-pattern. Facial disc is expressed only in bottom part. Breast is black and brown longitudinal streaked. Flacks and belly have character cross-pattern which is different in each geographical races. Tarsus and toes are full feathered. Eyes are orange-red, bill and claws are black. Females are larger than males. Young birds have variable background color - from orange-buff to pale-buff, with narrow cross-strips; throat is white; above the eyes there are two dark patches. Tail and flight feathers are colored as on adults, and not changed in first autumn moulting.
Breeds and occurs on wintering almost throughout in Kazakhstan. Please see the detailed distribution in Kazakhstan in the section Subspecies.
Eagle Owl is rare resident. It inhabits plain and hilly areas with rocks and cliffs, chinks or precipitates in river valleys, in dense deciduous, mixed or coniferous forests, in Tien Shan up to 3000 m. Eagle Owl breeds in separate pairs, fairly far each of other. Breeding territory is stable and is used by birds year in year out, in case of absence of external troubles. Nest is placed in cave; in hollow under stone; on ground near woodblock; under brushwood; nest is without any special materials. Clutches of 2-5 eggs is founded from mid-March to April. Female incubates for 35 days and male feed her. Nestlings hatch in end April at southern areas, and in late May on Altai. At first time male bring food to nest and female give it to chicks, but later both parents hunt for food. Juveniles fledge in end May - mid-July. Repeated breeding after losing of first clutch occurs. Broods break-up in September, and young birds disperse singly not far from birth area.
 Bubo bubo ruthenus (Zhitlov et Buturlin, 1906)Description. Background colour is rusty-yellow with expressed greyish tinge. Dark pattern on upper- and under-parts is brownish-black. Wing coverts have whitish spots. Dark pattern on upper parts (head, back and shoulders) occupies less area than background. Male wing length 430-468, female 471-515 mm. |
 Bubo bubo sibiricus (Gloger, 1833)Description. The lightest race. Background colour is buffy-whitish. Dark pattern on upper- and under-parts is slightly expressed and has black-brownish colour. Wing coverts and scapulars have well expressed large whitish spots. Dark pattern on upperparts (head, back and shoulders) considerably reduced. Male wing length 438-465 (451), female 472-515 (492) mm. |
 Bubo bubo yenisseensis (Buturlin, 1911)Description. Darker than sibiricus. Background colour is buff-greyish. Dark pattern on upper- and underparts is well expressed and has brownish-black colour. Dark pattern on upperparts (head, back and shoulders) occupies less area than background, irregular and not formed solid dark sets. Males wing length 443-468, female 473-518 mm. |
 Bubo bubo turcomanus (Eversmann, 1835)Description. Background colour is pale, yellowish-buff. Dark pattern on upper- and underparts is paler, less espressed and more shattered than in interpositus. Dark longitudinal pattern on underparts is not covered to belly. Male wing length 420-468, female 470-492 mm. |
| Bubo bubo omissus (Dementiev, 1933) Description. Background colour is buffy-yellow, more pale; dark pattern on upper- and underparts less expressed than in turcomanus. Dark shaft-streaks on nape are very narrow. Dark longitudinal pattern on underparts not covered to belly. Dark cross-pattern on belly and flanks is thinner and paler than in turcomanus. Male wing length 404-424, female 425-460 mm. |
 Bubo bubo hemachalanus (Hume, 1873)Description. This race is close to turcomanus but background colour is more yellowish, less buff. Dark pattern on upper- and underparts some more expressed and less regular than in turcomanus and omissus. Dark longitudinal pattern on underparts covered on fore-belly. Male wing length 433-466, female 473-508 mm. |
"Птицы Казахстана" том 2. "Наука". Алма-Ата, 1962.
Э.И.Гаврилов. "Фауна и распространение птиц Казахстана". Алматы, 1999.
Gavrilov E. I., Gavrilov A. E. "The Birds of Kazakhstan". Almaty, 2005.
