Northern Spotted Owl

Strix occidentalis caurina

Description

The northern spotted owl, one of three spotted owl subspecies, is a medium-sized owl with a round head, dark brown plumage, and dark eyes. It has white spots on the head and neck and white mottling on the breast and abdomen. The female is slightly larger than the male and has a higher pitched call. Juveniles go through a series of downy plumages in their first summer; afterwards they are distinguishable from adults only by ragged white downy tips on their tail feathers.

The northern spotted owl is distinguished from the two other subspecies—the California spotted owl (Strix occidentalis occidentalis ) and the Mexican spotted owl (S. o. lucida )—by slight differences in plumage and their respective geographic ranges. The Mexican spotted owl was proposed for listing as threatened in November 1991.

Behavior

The northern spotted owl inhabits a relatively large home range, which it uses for nesting, foraging, and roosting. It usually spends the entire year on its territory.

Like most other owls, it is primarily nocturnal, swooping down from perches to take prey. Its diet consists mostly of small mammals, but also includes birds, reptiles, and insects. The most important prey are flying squirrels (Glaucomys sabrinus ), red tree voles (Arborimus longicaudus ), and dusky-footed woodrats (Neotoma fuscipes ).

Owl pairs do not nest every year, and not all nesting attempts are successful. It is believed that nesting patterns may be related to local prey availability. Nesting behavior begins in February and March, and nests are located almost exclusively in tree cavities or platforms. Pairs do not build their own nest but use cavities at the broken tops of old-growth conifers, nests built by other birds or mammals, and naturally occurring platforms. Females lay a clutch of two eggs in March or early April, and incubate them for about 32 days. The male feeds the female and young during incubation and brooding. The young leave the nest after about a month and remain near the nest where they are fed by the adults until early fall. The young disperse in September or October.

Young northern spotted owls have a much higher mortality rate than adult birds. Studies have found that only about 19% survived their first year. The principal causes of juvenile death appeared to be starvation and predation by great horned owls.

Habitat

The northern spotted owl inhabits old-growth forests or mixed stands of old-growth and mature trees. Pairs establish extensive territories, which are used for nesting, foraging, and roosting. The sub-species is occasionally found in younger forests that have remnant patches of large trees or scattered individual large trees. Old-growth forests possess a combination of characteristics required by the owl: a high, multistory canopy dominated by large trees; numerous trees with cavities or broken tops; woody debris or fallen trees; and open space beneath the canopy for flying.

The size of a pair's home range varies across the subspecies' geographical distribution. The median size of a pair's home range is about 10,000 acres (4,050 hectares) for the Olympic Peninsula; 6,300 acres (2,550 hectares) for the Washington Cascades; 3,000 acres (1,200 hectares) for the Oregon Cascades; 4,800 acres (1,950 hectares) for the Oregon Coast Range; and 3,300 acres (1,350 hectares) for the Klamath Provence.

Distribution

The precise historic range of the northern spotted owl cannot be known with certainty. Early European settlers began cutting the old-growth forests, particularly in coastal and foothill areas, before the owl's range was determined. Researchers generally believe that the owl inhabited all suitable habitat from southern British Columbia to northern California. There are no historic population estimates.

Northern spotted owls are found in what old-growth forest remains throughout the subspecies' historic range. By the late twentieth century, most privately owned old-growth forest had been cut; approximately 90% of the remaining old-growth forest was on federal land managed by the U. S. Forest Service, U. S. Bureau of Land Management (BLM), and the National Park Service. The early twenty-first century range was from southwestern British Columbia, south through western Washington, western Oregon, and northern California to near San Francisco Bay. The southern boundary that separated the northern spotted owl from the California spotted owl was the Pit River area of Shasta County, California.

Northern spotted owls were not uniformly distributed throughout this range. Most inhabited the Cascades in Oregon and the Klamath Mountains of southwestern Oregon and northwestern California. Densities were lowest in northern Washington, southern British Columbia, and northeastern California. Approximately 2,000 breeding pairs were known, and the total population was estimated to number between 3,000 and 5,000 pairs.

Threats

The principal threat to the northern spotted owl is the ongoing reduction of its old-growth forest habitat through logging. Nearly all privately owned old-growth forest has already been cut in the Pacific Northwest, and suitable spotted owl habitat is almost completely confined to federal land. Conflict over forest management practices to conserve the spotted owl date to at least the mid-1970s when wildlife officials in Oregon, in concert with federal scientists, attempted to establish a state management plan for the subspecies.

Conservation and Recovery

The decision to list the northern spotted owl and institute a conservation plan has generated more controversy than any other action taken under the Endangered Species Act in several decades. Citing a threat to the regional economy, companies, organizations, and localities dependent on the timber industry vigorously opposed any action that would reduce the timber cut on federal land in the Pacific Northwest. A coalition of environmental organizations and independent and government scientists has been equally vigorous in pressing for additional protection for the region's old-growth forests which serve as the owl's habitat.

Following a January 1987 petition from a private conservation organization to list the owl, the U. S. Fish and Wildlife Service (FWS) determined in December 1987 that listing the owl was not warranted. The Sierra Club Legal Defense Fund then challenged that decision by filing a lawsuit against the FWS in the U. S. District Court for the Western District of Washington (Northern Spotted Owl v. Hodel, no. C88-573Z). On November 17, 1988, the court found that FWS's failure to list the northern spotted owl was "arbitrary and capricious or contrary to law" and directed the service to reconsider its decision. Following this judicial rebuke, the FWS organized a special listing review team to evaluate the scientific evidence concerning the threat to the owl. In June 1989, the FWS proposed that the northern spotted owl be listed as threatened. The listing was made final on June 26, 1990. Meanwhile the controversy between timber interests and environmentalists had escalated into a major political debate over the health of the local economy versus conservation of the owl and its old-growth forest habitat.

In 1989, while the listing proposal was under consideration, an interagency scientific committee was established to develop a conservation plan for the owl. On April 2, 1990, it issued a report, "A Conservation Strategy for the Northern Spotted Owl" (popularly known as he "Jack Ward Thomas Report," after the committee's chairman). This report recommended the establishment of habitat conservation areas on nearly eight million acres (3.2 million hectares) of federal land throughout the owl's range. The conservation plan called for a network of individual reserves, each large enough to support a minimum of 20 pairs of owls. No logging would be allowed on these reserves, and a strict timber management policy would apply on federal land connecting the conservation areas.

In February 1991, the FWS was ordered by the U. S. district court presiding over Northern Spotted Owl v. Hodel to designate critical habitat for the owl. On May 6, FWS proposed a network of critical habitat areas totaling more than 11 million acres (4.5 million hectares) of federal, state, and private land in Washington, Oregon, and California. These areas were largely based on the habitat conservation areas mapped in the Jack Ward Thomas Report. On August 13, 1991, the FWS revised its proposal to include only federal and state land. It proposed that approximately 8.2 million acres (3.3 million hectares) be designated as critical habitat. The final determination was made on January 9, 1992, when the FWS announced that critical habitat for the owl would encompass approximately 6.9 million acres (2.8 million hectares) of federal land.

The listing of the northern spotted owl as threatened and the determination of its critical habitat has hardly ended the political or legal struggle. On May 23, 1991, a U. S. district judge ordered the suspension of timber sales in the national forests of the Pacific Northwest until the Forest Service produced an effective protection plan for the northern spotted owl.

And on September 30, 1991, Secretary of the Interior Manuel Lujan decided to convene the Endangered Species Committee, sometimes known as the "God Committee," to consider a BLM request for an exemption from the Endangered Species Act. The BLM was seeking permission to sell timber from about 4,000 acres (1,600 hectares) of northern spotted owl habitat. While this was only a small portion of the owl's critical habitat, proponents of protecting the owl regarded this as the first step in a campaign to weaken the provisions of the Endangered Species Act.

Contact

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov/

References

Forsman, E., and E. C. Meslow. 1986. "The Spotted Owl." In Audubon Wildlife Report 1986. Academic Press, San Diego.

Thomas, J. W., et al. 1990. "A Conservation Strategy for the Northern Spotted Owl." U. S. Department of Agriculture, U. S. Forest Service, U. S. Department of the Interior, U. S. Fish and Wildlife Service, U. S. Bureau of Land Management, and National Park Service, Portland.

U. S. Fish and Wildlife Service. 9 January 1992. "Determination of Critical Habitat for the Northern Spotted Owl." Federal Register 57.