Published: July 2023
Author(s): Joseph B. Buchanan
The Northern Spotted Owl (Strix occidentalis caurina; hereafter, Spotted Owl) was listed as an Endangered Species in Washington by the Washington Fish and Wildlife Commission in 1988, and was listed as a Threatened Species under the Endangered Species Act (ESA) 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 northern California. Spotted Owls have very large home ranges (thousands of acres) and use mature and old coniferous forest for nesting, roosting, and foraging; loss of habitat due to timber harvest was the primary reason for its ESA listing. Protections on federal (Northwest Forest Plan) and nonfederal lands (Forest Practices Rules) have reduced the amount of habitat loss due to timber harvest. Population monitoring at three demography study areas in Washington indicate annual rates of change between -5.0 and -9.0% through 2018, continuing an ongoing downward trend for the last three decades.
The closely related Barred Owl (Strix varia) expanded its range across North America and arrived in Washington over 55 years ago. The range of the Barred Owl has continued to expand, and it now occurs throughout the range of the Northern Spotted Owl. The Barred Owl has life history traits that enable it to be an effective competitor of the Spotted Owl for resources, and this competitive interaction is now the primary driver of 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 2015, a landscape-scale experiment to remove Barred Owls from Spotted Owl territories at four study areas was implemented; one of the study areas was in the eastern Cascade Range in Washington. Results of the experiment indicated a positive response by Spotted Owls to the removal of Barred Owls. The USFWS is currently working to develop a management strategy to benefit Spotted Owls in the Pacific Northwest and California by managing Barred Owls.
The decline of Spotted Owls has not subsided in Washington and the population has become critically imperiled, having declined by up to 80-90 percent in some predominantly federal landscapes in Washington. The U.S. Fish and Wildlife Service has concluded that uplisting the Spotted Owl from threatened to endangered status under the Endangered Species Act was “warranted but precluded.” We recommend the continued recognition of Endangered status of the species in Washington.
Buchanan, J. B. 2023. Draft periodic status review for the Northern Spotted Owl in Washington. Washington Department of Fish and Wildlife, Olympia, Washington. 26 + iii pp.