Dietary biology of the golden eagle
Owls, which may have dissimilar periods of activity, are not entirely exempt from golden eagle predation either. Several species have been recorded as prey, especially in Northern Europe, Slovakia (where owls make up 2.4% of prey remains) and some parts of the Western United States. Species hunted have ranged in size from tiny Eurasian pygmy owl ("Glaucidium passerinum") and little owl ("Athene noctua") to the formidable, large great horned, Eurasian eagle and great gray owls ("Strix nebulosa"). Barn owls ("Tyto alba") have been predated by golden eagles in both North America and Eurasia. On Santa Rosa and Santa Cruz Islands, barn owls made up 4.5% of the diet, the largest known occurrence of that species in the eagles' diet. However, the great horned owl is the owl species that occurs most regularly in the diet of North American golden eagles. In Europe, golden eagles are relatively minor predators of owls compared to Eurasian eagle-owls and northern goshawks. The primary owls hunted by European eagles are Ural owls ("Strix uralensis") and short-eared owls ("Asio flammeus"). Few eye-witness accounts are known of owl predation, but one violent mid-day confrontation between a golden eagle and an adult great horned owl was witnessed in Jefferson County, Colorado. Although this owl was about a third of the eagle's weight, it was able to land some damaging blows on the larger bird. In the end, despite its wounds, the eagle was victorious over the dead owl. A case of kleptoparasitism by a golden eagle on a great horned owl has been recorded. Although the Eurasian eagle-owl is preyed upon by golden eagles (4 confirmed cases of golden eagles killing eagle-owls in Europe), in one case a golden eagle (age unspecified) was found amongst the prey in an eagle-owl nest.
Ural owl
The Ural owl ("Strix uralensis") is a medium-sized nocturnal owl of the genus "Strix", with up to 15 subspecies found in Europe and northern Asia.
The Ural owl is smaller than the great grey owl, and much larger than the tawny owl, which it superficially resembles. Distinguishing features apart from the size are the pale, buffish grey-brown plumage, with copious dark brown streaking on the back of the head and underparts. It has a round head with plain buffish-grey facial discs, orange-yellow bill and small black eyes. The tail is long and wedge-shaped, with dark barring on the upper tail, and the wings are rounded. Flight is direct and purposeful, recalling that of the common buzzard. Sexes are similar, with no seasonal variation. Length can range and wingspan from . Weight in males is and in females is .