Strix occidentalis lucida

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

Differs from other subspecies in being generally paler and having the lighter markings of the underparts more whitish (Ridgway 1914).

Nesting and roosting occurs in both forested and rocky-canyon habitats. Forests used for roosting and nesting often contain mature or old-growth stands with complex structure; typically they are uneven-aged, multistoried, and have high canopy cover; nest trees are typically large Douglas-fir, though other species sometimes are used. In parts of its range, Mexican spotted owls occupy a variety of steep, rocky-canyon habitats. The owls appear to use a wider variety of cover types for foraging than for roosting or nesting. Source: USFWS (2012).

Highest densities occur in mixed-conifer forests that have experienced minimal human disturbance (USFWS 1995, Ganey and Dick 1995). In the southwestern U.S., these owls are most common where unlogged closed canopy forests occur in steep canyons; uneven-aged stands with high basal area and many snags and downed logs are most favorable. In Arizona, owls occur primarily in mixed-conifer, pine-oak, and evergreen oak forests; also in ponderosa pine forest and rocky canyonlands (Ganey and Balda 1989). In Arizona, spotted owls generally foraged more than or as frequently as expected (based on availability) in virgin mixed-conifer and ponderosa pine forests, and less than expected in managed forests; they roosted primarily in virgin mixed-conifer forests; both foraging and especially roosting sites had more big logs, higher canopy closure, and greater densities and basal areas of both trees and snags than did random sites (Ganey and Balda 1994). In southern Utah, spotted owls commonly used mesa tops, benches and warm slopes above canyons in fall and winter; relatively cool canyons were the primary summer habitat (see USFWS 1994). In New Mexico, breeding and roosting occurred in mixed-conifer forests that contained an oak component more frequently than expected by chance; generally did not use pinyon pine-alligator juniper woodlands for nesting or roosting; selected roost and nest sites in forests characterized by mature trees with high variation in tree heights and canopy closure greater than 75% (Seamans and Gutierrez 1995).

Mexican spotted owls are basically intolerant of even-age forest management practices (USFWS, Federal Register, 1 April 1994). They require cool summer roosts (Barrows 1981, Ganey et al. 1993), such as near canyon bottoms, in dense forests, on shady cliffs or in caves (Ganey et al. 1988). Sometimes they occur in deep canyons in areas that lack extensive forests. Sometimes they winter in comparatively open habitats at lower elevations. Breeding formerly occurred in desert riparian habitat, but occurrences are rare in this habitat today. In general, foraging habitat requirements are not well known (USFWS 1995). See USFWS (1993, 1994, 1995) for further details on habitat.

Nests are on broken tree tops, cliff ledges, in natural tree cavities, or in trees on stick platforms, often the abandoned nest of a hawk or mammal; sometimes in caves. In Utah and Colorado, most nests are in caves or on cliff ledges in steep-walled canyons; elsewhere, nests apparently most often are in trees, especially Douglas-fir (USFWS 1995, Seamans and Gutierrez 1995). Mexican spotted owls exhibit a high level of nest site fidelity. Typically they select cool, shady sites with high canopy closure and at least a few old-growth trees, usually on moderate to steep slopes (USFWS 1993). In New Mexico, 61% of nest structures were on clumps of limbs caused by dwarf mistletoe infections; nest trees averaged 164 years old and 60.6 cm in diameter (Seamans and Gutierrez 1995). See also USFWS (1995).

Density generally is less than 0.4/sq km (mostly about 0.1-0.2/sq km) (USFWS 1995). Annual survival rate appears to be about 80-90% in adults, 6-29% in juveniles (White et al. 1995, USFWS 1995).

Egg dates: peak in April in Arizona and New Mexico, sometimes as early as early March. Clutch size is 2-4, usually 2. Incubation, by female (fed by male), lasts about 30 days. Hatching generally occurs in early to mid-May. Young leave nest at about 5 weeks (June), fly at about 6-7 weeks, stay near nest for several weeks, fed by adults until late summer, independent by early fall (dispersal of young occurs in September-October). First breeds at 2-3 years; may not breed every year. Reproductive success generally is low (USFWS 1993); average number of young fledged per pair is about 1.0 (USFWS 1995).