Published: February 2016
Author(s): Joseph B. Buchanan
The Northern Spotted Owl (Strix occidentalis caurina; hereafter, Spotted Owl) was listed as an Endangered Species in Washington State by the Washington Fish and Wildlife Commission in 1988, and was listed as a Threatened Species under the Endangered Species Act in 1990. This is one of three Spotted Owl subspecies and the only one to occur in the Pacific Northwest. Its distribution is from extreme southwestern British Columbia south through the Cascade Range and coastal mountains to northwestern California. Spotted Owls have very large home ranges (thousands of acres) and use mature and old coniferous forest habitat for nesting, roosting and foraging; loss of this habitat due to timber harvest was the primary reason for its listing. Protections on federal (Northwest Forest Plan) and nonfederal lands (Forest Practices Rules) have reduced the amount of habitat loss, although authorized habitat loss continues under these and other initiatives such as federal habitat conservation plans. Population monitoring at three demography study areas in Washington indicate annual rates of change between -3.9 and -8.4%. The closely related Barred Owl expanded its range across North America and arrived in the Pacific Northwest about 45 years ago. The range of the Barred Owl has continued to expand, and it now is found throughout the range of the Spotted Owl. The Barred Owl has life history traits that enable it to be a more effective competitor of resources than the Spotted Owl, and this competitive advantage has contributed substantially to the continuing population decline of the Spotted Owl in Washington. A variety of management actions are underway to enhance Spotted Owl conservation in Washington and elsewhere within its range. In particular, a landscape-scale experiment to remove Barred Owls from Spotted Owl territories at four study areas was implemented in autumn of 2015; one of the study areas is in the eastern Cascade Range in Washington. The decline of Spotted Owls has not subsided in Washington and the population is becoming critically imperiled. The U.S. Fish and Wildlife Service currently is evaluating whether to change the speciesâ€™ status to Endangered under the Endangered Species Act. We recommend that the status remain as Endangered in Washington State.
Buchanan, J. B. 2016. Periodic status review for the Northern Spotted Owl in Washington. Washington Department of Fish and Wildlife, Olympia, Washington. 22 + iv pp.
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