Bubo virginianus
(Great Horned Owl)

Physical Description:
18-25" (46-64 cm). Large owl with ear tufts set wide apart. Mottled gray-brown above with closely spaced, fine dark gray horizontal barring below. Conspicuous white throat bib below a tawny face.

Similar Species- Long-eared Owl

Song:
A deeply resonant hooting, usually uttered 5-6 times.

Distribution:
Breeds from western and central Alaska, east to southern Keewatin and Labrador, and south to southern South America. Winters generally throughout breeding range. Northernmost populations are partially migratory, wintering south to southern Canada and northern United States. Species is most common and widely distributed owl in Idaho.

Habitat:
Found in various moist or arid forested habitats, from lowland forests (deciduous or evergreen) to open temperate woodlands, including second-growth forests, swamps, orchards, riverine forests, brushy hillsides, and desert.

Diet:
Broad diet; eats mainly mammals (commonly mouse to rabbit size), and small to large birds (including hawks and waterfowl) but also amphibians, reptiles, and invertebrates. Idaho study found voles and deer mice were main food items. Parents provide about 300 g of food per day, per nestling.

Ecology:
Hunts from perch; captures prey on ground. Caches food. Utilizes abandoned stick nest in tree, cliff ledge, or man- made platform. Productivity peaks with snowshoe hare population in northern range. Size of home range varies seasonally and geographically. density varies, but is usually about 1 pair/5-21 km2. Idaho study found density of 1.7 owls/10 km2; juvenile survival was 1.8/nest.

Female incubates 2-3 eggs for 26-35 days; male supplies food. Young leave nest at 4-5 wk, fly well at 9-10 wk, and are dependent on parents for several wk. Most yearling females do not nest. Female may re-lay if first clutch is lost.

Conservation:

Element Code:	ABNSB05010
Status:	Protected nongame species
Global Rank:	G5
State Rank:	S5
National Rank:	N5

Important State References:
Frounfelker, C.R. 1977. Prey selection of the great horned owl with reference to habitat and prey availability. M.S. Thesis, Univ. Idaho, Moscow. 62pp.