endemic to a single nation, and breeds in a single state or province

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (20,000-200,000 square km (about 8000-80,000 square miles)) Range encompasses part of California and possibly northern Baja California, from southeastern Shasta County south through the Sierra Nevada (almost all sites on west slope) to Kern County; Coast/Peninsular Ranges from Monterey County to San Diego County; possibly the Sierra San Pedro Martir in northern Baja California (Dawson et al. 1987). Elevational range extends up to 2,300 meters in northern Tulare County. See detailed spot map and list of localities in Gould (1977).

Length: 45 cm

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 GTAXCOM.

Comments: 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.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Adults may migrate downslope in fall, return to higher elevation in spring; fall (mid-October to mid-November) movements averaged 31 km with a change in elevation averaging 754 m in the Sierra Nevada, California (Dawson et al. 1987, Laymon 1989).

In and around Lassen National Forest in northeastern California, a small percentage (7 percent) of banded owls changed breeding locations between years; dispersal distance was 1-33 kilometers (mean 7 km); most dispersal events resulted in increased territory quality for the dispersing owl (Blakesley et al. 2006).

Pair home range size averages 3400 acres; range may or may not shift seasonally (Neal et al., in Spahr et al. 1991). Median June-December home range of 5 owls was 1070-2230 ha (Call et al. 1992).

In the San Bernardino Mountains in southern California, 67 juvenile males and 62 juvenile females dispersed 2.3-36.4 kilometers (mean 10.1 km) and 0.4-35.7 km (mean 11.7 km), respectively, from their natal sites (LaHaye et al. 2001). Over half of the successful dispersers became territorial within one year; all females and 95% of the males occupied territories within three years.

Despite the banding of several hundred individuals in southern California mountain ranges, no intermountain movements have been recorded (LaHaye et al. 1994).

Comments: Small mammals, particularly nocturnal arboreal or semi-arboreal species, predominate in diet; mostly Glaucomys, Neotoma and Sciurus. Breeders take larger rodent prey than do nonbreeders (Thrailkill and Bias 1989). Generally hunts from perch. May cache prey.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 - 300

Comments: This subspecies is represented by a large number of occurrences (subpopulations).

2500 - 10,000 individuals

Comments: A minimum of 3,050 individuals were detected between 1970 and 1992 (Gutiérrez 1994). As of the early 1990s, 1,008 pairs and 436 single birds were known to occur in the Sierra Nevada; 598 individuals were known from 15 other populations (range 6-270 individuals/population) (Beck and Gould 1992, LaHaye et al. 1994).

Comments: Roosts during the day; hunts at dusk and at night. May leave roost during day to capture prey beneath roost, retrieve cached prey, or to drink or bathe in stream.

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.

United States

Rounded National Status Rank: N3 - Vulnerable

Rounded Global Status Rank: T3 - Vulnerable

Reasons: Fairly large number of occurrences, but relatively few are of high quality, and population trend is downward, due to past and continuing loss, degradation, and fragmentation of habitat.

Intrinsic Vulnerability: Moderately vulnerable

Comments: Small clutch size, temporal variability in nesting success, and delayed onset of breeding all contribute to the relatively low fecundity of this species (Gutiérrez 1996).

Other Considerations: This is a high profile species to which apply a large number of policies and regulations.

Global Short Term Trend: Decline of 10-30%

Global Long Term Trend: Increase of 10-25% to decline of 50%

Comments: Verner et al. (1992) were uncertain about the possibility of a decline in the Sierra Nevada population. They stated that the owl's current distribution and abundance do not suggest that the species has declined either in overall distribution in the Sierra Nevada or that it has declined markedly in abundance within any forest type. However, they noted concern over declining habitat quality (see threats comments). Verner et al. (1992) reported that the population in southern California declined steeply in the late 1980s and early 1990s.

Demographic parameter estimates by Seamans et al. (2001) indicated that the population in the central Sierra Nevada declined 5.2 percent per year during the years 1990-1999.

A study of population dynamics of California spotted owls from four locations in the Sierra Nevada and one location in southern California (San Bernardino Mountains), spanning the years 1986-2000 overall, found suggestive but not conclusive evidence of an overall population decline (Franklin et al. 2004).

Demographic data collected in and around Lassen National Forest in northeastern California indicated an annual rate of decline in the territorial population of 9% per year over the period of study (1990-1999) (Blakesley et al. 2001).

Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable

Comments: Habitat continues to be lost or degraded by logging and/or forest fragmentation. Verner et al. (1992)noted concern over the rapid disappearance of the large, old, and generally decadent trees that are the focus of nesting by spotted owls. Additionally, they hypothesized that drought-induced declines in woodrat populations may have played a role in the owl decline in southern California.

Interactions with barred owls may develop into a significant threat. Seamans et al. (2004) reported a hybrid spotted owl x barred owl as far south in the Sierra Nevada as Placer County, California. This owl may have displaced a pair of spotted owls from the occupied site.

Based on data from all three spotted owl subspecies, Bond et al. (2002) hypothesized that noncatastrophic "wildfires may have little short-term impact on survival, site fidelity, mate fidelity, and reproductive success of spotted owls. Further, prescribed burning could be an effective tool in restoring habitat to natural conditions with minimal short-term impact on resident spotted owls."

Preserve Selection and Design Considerations: Based on demographic models, a protection of a smaller numer of fairly large preserves, each including 10-20 active nests, may be preferable to preserving a larger number of small preserves (Andersen and Mahato 1995).

Management Requirements: Greatest management need is protection of large contiguous blocks of habitat capable of supporting multiple pairs.

Lee and Irwin (2005) used published literature and data from the southern Sierra Nevada to examine the potential effects of landscape-level reductions in canopy cover (CC) on owl occupancy and reproduction. Using a combination of population data, canopy cover measurements, and forest simulation models, they showed that modest fuels treatments in the Sierra Nevada would not be expected to reduce canopy cover sufficiently to have measurable effects on owl reproduction. Sixty-year simulations predict that mechanical thinning or mechanical thinning plus fuel-break construction treatments in combination with either no fire or mixed-lethal fire scenarios will not degrade canopy conditions in productive owl territories, nor impede improvement of non-productive territories. In contrast, lethal fire simulations produced a pronounced and lasting negative effect. Their analysis supports the hypothesis that habitat needs for owl reproduction can be incorporated in developing effective fire and fuels management strategies that lessen the chances of uncharacteristic wildfire.

Management Research Needs: Determine population attributes and trends in relation to existing management activities. Determine silvicultural techniques that could produce wood products and owls. Determine ways to make younger forests capable of supporting owls.

Global Protection: Few to several (1-12) occurrences appropriately protected and managed

Comments: Many occurrences are in national parks and other protected areas, but this does not necessarily ensure the absence of significant threats in those areas. Logging is restricted in a number of occupied areas in national forests, national parks, wilderness areas, and BLM lands.

Needs: Protect large tracts of old growth forest or younger forest of similar vegetative structure.