Strix occidentalis occidentalis

A large, dark-eyed, round-headed, dark brown owl with white spotting on the head, back, and underparts (spotted breast, barred belly).

Differs from subspecies caurina in being paler and having the legs and feet less heavily mottled (Ridgway 1914). Supposedly differs from subspecies lucida in having underparts with much more buff and correspondingly less white (Ridgway 1914), but see taxonomic comments under the full species.

Typical habitat is dense, multi-layered evergreen forest that includes a diversity of tree species, large trees (some greater than 83 cm DBH), some trees with evidence of decadence, and open areas under the canopy; most often on lower, north-facing slopes of canyons, usually within 0.3 km of water (Gould 1977, Bias and Gutiérrez. 1992). Foraging owls selected macrohabitats composed of larger trees (>52 cm dbh) with canopy closures of 40% and greater; used microhabitats characterized by multiple vegetative strata, large tree size classes, high tree basal areas, and woody debris (Call et al. 1992). Commonly inhabited plant associations include: canyon live oak/California laurel (lower elevations of southern Coast Range); ponderosa pine, or sugar pine, Coulter pine, and/or incense cedar (higher elevations of southern Coast Range); mixed conifer forest, usually dominated by ponderosa pine (southern Sierra Nevada); ponderosa pine, Douglas-fir, and/or white fir (northern Sierra Nevada) (Gould 1977). Spotted owls may persist in areas where up to 10-30% of the available habitat has been removed by clear-cutting (Gould 1977).

In the central Sierra Nevada, 97 percent of the habitat patches in which owls roosted were characterized by the presence of residual trees (greater than 100 cm dbh); owl roost and nest sites were also characterized by residual trees and high structural diversity (Moen and Gutiérrez 1997).

Nests are on broken tree tops, cliff ledges, in natural tree cavities, or in tree on stick platforms, often the abandoned nest of hawk or mammal; sometimes in caves. This owl exhibits a high level of nest site fidelity.

Egg laying occurs mainly early to mid-April. Clutch size is 2-4, usually 2. Incubation, by female (fed by male), lasts about 30 days. Hatching occurs in early to mid-May. Young leave nest at about 5 weeks, fly at about 6-7 weeks, stay near nest for several weeks, fed by adults until late summer, independent by early fall. First breeds at 2-3 years; may not breed every year.