Owl, Northern Spotted

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Owl, northern spotted

Strix occidentalis caurina

phylum: Chordata

class: Aves

order: Strigiformes

family: Strigidae

status: Lower risk: near threatened, IUCN Threatened, ESA

range: Canada (British Columbia), USA (California, Oregon, Washington)

Description and biology

The northern spotted owl is one of three subspecies of spotted owl. This owl has chocolate brown plumage (covering of feathers) that is speckled with white or light brown spots. It has a round face and dark eyes surrounded by light facial disks. An average northern spotted owl measures 16 to 19 inches (41 to 48 centimeters) long and has a wingspan of about 42 inches (107 centimeters). Females are slightly larger than males.

Northern spotted owls have very keen hearing and vision. Although sometimes active during the day, they are mainly nocturnal (active at night). They perch on trees and then swoop down to catch their prey. Mammals—especially the northern flying squirrel—make up 90 percent of the owl's diet. Birds and insects make up the other 10 percent. Predators of the northern spotted owl include the great horned owl, the northern goshawk, and the red-tailed hawk.

The northern spotted owl's home range can vary widely. Depending on the amount of food available in the area, the type of habitat, and the geographic location, this range can extend from 2,000 to 14,000 acres (800 to 5,600 hectares). Biologists (people who study living organisms) believe male and female northern spotted owls mate for life. The female lays a clutch (eggs produced at one time) of 2 to 4 eggs in a naturally occurring nest such as a broken-top tree or a cavity in an older tree. She alone incubates (sits on or broods) the eggs. During incubation, the male hunts for food. After the nestlings hatch, they are cared for by both parents until they leave the nest three to five weeks after birth.

Habitat and current distribution

The northern spotted owl is found from southern British Columbia, Canada, south to Marin County, California (the other subspecies inhabit California, the U.S. Southwest, and Mexico). In the northern part of this area, the owl's range extends from sea level up to elevations of 5,000 feet (1,524 meters). In the southern part, its range extends to elevations of 7,500 feet (2,286 meters). Although not quite sure, biologists believe between 3,000 and 5,000 pairs of northern spotted owls currently exist in the wild.

This owl lives almost exclusively in old-growth forests dominated by Douglas fir, western hemlock, and redwood trees. "Old growth" refers to forests made up of trees that are at least 200 years old and that haven't been cut or altered in any way by man. Additionally, the physical structure of an old-growth forest is very complex. It has multiple layers in its canopy, trees of varying sizes, and many standing dead trees and dead logs that provide cavities for nesting sites.

History and conservation measures

The northern spotted owl has been at the center of a battle between lumber companies and environmentalists. Timber from old-growth forests is highly valued by loggers because of its fibrous, grainy nature. The Pacific Northwest region has some of the last remaining old-growth forests in America, and roughly 80 percent of that has already been cleared. Of the forest that remains, 90 percent is on federally owned land. Once the northern spotted owl was placed on the Endangered Species List in 1990, logging of the remaining old-growth forests was curtailed, and the debate over the fate of old- growth forests and the northern spotted owl became a federal issue.

Lumber companies have argued that preserving old-growth forests will simply cost jobs—as many as 12,000 people would be put out of work. Environmentalists counter that the lumber companies are simply delaying what is destined to happen: at the rate lumber companies are cutting trees, the old-growth forests will soon disappear, and just as many people will become unemployed. In addition, old-growth forests are necessary for the survival of many species, such as the northern spotted owl, the marbled murrelet, and the red-cockaded woodpecker.

In 1995, the U.S. Fish and Wildlife Service and the Weyerhaeuser Company (a lumber company) agreed to a recovery plan. The plan designated areas of forest as protected owl habitat. In between those areas, Weyerhaeuser was allowed to cut down enough timber to maintain its yearly production levels. The federal government and the lumber company hoped this was tthe beginning of a solution to save both jobs and the northern spotted owl. In 2000, after five years under this plan, it was reported that the decline in the owl population had slowed from 4.5 percent a year to 3.9 percent a year. The drop was far less than conservationists had hoped.