An overview of the northern spotted owl

This long mostly level alluvial plain has some scattered areas of low basalt, and contrasts with productive farmland and large urban areas. It has the fastest-growing human population in the state resulting in challenges due to land-use changes. Northern Spotted Owls require large areas of late-successional forest for breeding and dispersal. Northern Spotted Owls have large home range requirements.

An overview of the northern spotted owl

California, Oregon, Washington; British ColumbiaCanada 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. The Mexican spotted owl was proposed for listing as threatened in November 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 sabrinusred tree voles Arborimus longicaudusand 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.

An overview of the northern spotted owl

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. 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: The size of a pair's home range varies across the subspecies' geographical distribution.

An overview of the northern spotted owl

The median size of a pair's home range is about 10, acres 4, hectares for the Olympic Peninsula; 6, acres 2, hectares for the Washington Cascades; 3, acres 1, hectares for the Oregon Cascades; 4, acres 1, hectares for the Oregon Coast Range; and 3, acres 1, 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. 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. Densities were lowest in northern Washington, southern British Columbia, and northeastern California.The northern spotted owl (Strix occidentalis caurina) is one of three subspecies of spotted owl.

Like all spotted owls, the northern spotted owl lives in old-growth forests.

Conservation endocrinology

Although it is often considered to be a medium-sized owl, the northern spotted owl ranks among the largest in North America. The Northern Spotted Owl (Strix Occidentalis) is a nocturnal, woodland owl native to the temperate rainforests of the Pacific Northwest, Western Canada, and Alaska whose survival is tied directly to the health of old growth forest ecosystems, and as such, had assumed the role of an indicator species for the health of these ecosystems.

Basic Description. In the s the Spotted Owl was catapulted into the spotlight over logging debates in the Pacific Northwest.

This large, brown-eyed owl lives in mature forests of the West, from the giant old growth of British Columbia and Washington, to California's oak . The northern spotted owl, Strix occidentalis caurina, is the flagship threatened species of the Pacific monstermanfilm.comlly listed under the Endangered Species Act in , the northern spotted owl continues to decline at a rate of about 4% throughout its range.

Northern Spotted Owl - Oregon Conservation Strategy

The northern spotted owl is believed to have historically inhabited most forests throughout southwestern British Columbia, western Washington and Oregon, and . The northern spotted owl is a medium-sized, dark brown owl with a barred tail, white spots on the head and breast, and dark brown eyes surrounded by prominent facial disks.

Males and females have similar plumage, but females typically weigh 10 to 20 percent more than males.

Impacts of vehicle exposure on northern spotted owl | Center for Conservation Biology