The U.S. Fish and Wildlife Service listed the northern spotted owl as threatened under the Endangered Species Act in 1990. In 1994, the Northwest Forest Plan provided protections for the spotted owl and other species inhabiting late-successional forests in Washington, Oregon, and California. The spotted owl's first critical habitat designation came in 1992 and was revised in 2008. A new final rule designating critical habitat was published in December 2012. We first issued a recovery plan for the spotted owl in 2008 and revised it in 2011. A number of conservation partnerships are in place with public and private partners who contribute to spotted owl recovery. The two main threats to the spotted owl's continued survival are habitat loss and competition from the barred owl, a species native to eastern North America.
Historical Status and
The northern spotted owl is believed to have historically inhabited most forests throughout southwestern British Columbia, western Washington and Oregon, and northwestern California as far south as the San Francisco Bay. Loss and adverse modification of nesting, roosting, and foraging habitat due to timber harvesting, land conversions, natural disturbances such as fire and windstorms, and competition with encroaching barred owls have led to a decline of spotted owls throughout much of their historic range. In 2004, we completed a five-year review of the status of the northern spotted owl. We concluded that the species continues to warrant the protection of the Endangered Species Act as a threatened species. Today spotted owls are particularly rare in British Columbia, the Cascade Mountains of northern Washington, and the Coast Ranges of southwest Washington and northwest Oregon. A large and virtually isolated population persists on the Olympic peninsula. Estimates suggest that the amount of suitable habitat available to spotted owls has been reduced by over 60 percent in the last 190 years. Owl numbers appear to have declined annually since 1985 when many studies began. Spotted owls are currently declining at an average rate of 2.9 percent rangewide each year. Although the listing of the spotted owl as threatened and the designation of critical habitat offer some protection for the spotted owl, past trends suggest that much of the remaining unprotected habitat could disappear in 10 to 30 years.
Northern spotted owls live in forests characterized by dense canopy closure of mature and old-growth trees, abundant logs, standing snags, and live trees with broken tops. Although they are known to nest, roost, and feed in a wide variety of habitat types, spotted owls prefer older forest stands with variety: multi-layered canopies of several tree species of varying size and age, both standing and fallen dead trees, and open space among the lower branches to allow flight under the canopy. Typically, forests do not attain these characteristics until they are at least 150 to 200 years old.
Description and Life
A medium-sized, chocolate brown owl with dark eyes, the northern spotted owl is a nocturnal "perch-and-pounce" predator that captures its prey (primarily small forest mammals) with its claws. Like most owl species, the spotted owl nests in the tops of trees or in cavities of naturally deformed or diseased trees. Spotted owls primarily mate for life and may live up to 20 years. Although the breeding season varies with geographic location and elevation, spotted owls generally nest from February to June. One to four (usually two) pure white eggs are laid in the early spring and hatch about a month later. During incubation, the male typically does most of the foraging and brings food to the female and the young owlets. At three to four weeks of age, the owlets are able to perch away from the nest, but still depend on their parents for food. Predation on these juveniles by great horned owls and other predators is high at this time and many do not survive. Parental care of the juveniles generally lasts into September when the young owls finally take off on their own. This period, too, is hard for the young birds, and starvation is common in the first few months on their own.
Reasons for Decline
Prior to the listing of the northern spotted owl, timber harvesting and land conversions resulted in the loss of owl habitat. Forests with the late-successional and old-growth characteristics preferred by spotted owls are also preferred for timber harvesting to meet the demand for all types of forest products. As the amount of suitable habitat declines, so does the number of spotted owls. When spotted owls are forced to live in small patches of forest they become more susceptible to starvation, predation, or further loss of habitat due to natural destruction such as windstorms. More recently, competition from encroaching barred owls also has caused an apparent decline in spotted owls across most of their range. Barred owls are larger than spotted owls and more aggressive and have a broader diet which makes them more resilient to declines in habitat quality.
Recovery efforts for the northern spotted owl are helping to reduce habitat loss on federal lands. Although the need for timber necessitates continued harvesting, current forest management practices stress more limited harvesting in old-growth forests and suggest alternate areas for harvest which are less preferred by spotted owls. Careful planning of timber sales and forest conservation are necessary to halt the decline of the spotted owl and other old-growtth species. The Northwest Forest Plan, created in 1994, established a system of late-successional reserves (LSR) across the range of the spotted owl to provide suitable nesting habitat over the long term. The federal forest lands outside these reserves are managed to allow dispersal between the LSRs through riparian reserves and other land allocations. In 2011, we issued a Revised Recovery Plan for the Northern Spotted Owl that contains a wide array of recommendations, including protecting high-quality and occupied spotted owl habitat, actively managing forests to restore their health, and managing competition from the encroaching barred owl. We are currently proposing to conduct an experimental removal of barred owls from spotted owl habitat to assess the effect on spotted owls. We are also in the process of revising the spotted owl's critical habitat designation.
References and Links
Northwest Interagency ESA Website: Information on
the Endangered Species Act (ESA) and Streamlined Consultation Process. Website
Conservation Strategy: Conservation Strategy
for the Northern Spotted Owl. Interagency Scientific Committee.
Portland, Oregon. May 1990. Report(pdf
5-Year Status Review: Scientific evaluation of
the status of the Northern Spotted Owl. Sustainable Ecosystems Institute,
Portland, Oregon. September 2004. Report