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Spotted and Barred Owl
Spotted owl, listed as threatened under the Endangered Species Act, may be declining in the watershed. Their close relative—the barred owl—is increasing in numbers.
The northern spotted owl (Strix occidentalis caurina) is a medium sized (17.5 inches), dark-eyed owl. Spotted owls mate for life and may live up to 20 years.
In western Washington and Oregon, spotted owls require large patches of moderate-elevation late-successional or old-growth forest habitat for breeding.
(Strix varia) are larger (21 inches) than spotted owls. They have dark plumage like spotted owls, but they have barring and streaking rather than spots on their head and back.
Barred owls are native to the eastern United States, but have expanded their population to the west coast in the past few decades, likely as a result of changes people have made to the landscape. They first appeared in Washington in 1965.
Barred owls are more aggressive than spotted owls and use a wider range of habitats, including old-growth forest, mature second-growth forest, and riparian areas. Barred owls appear to be successfully competing with spotted owls in Washington and displacing them from old-growth forest.
In Washington the spotted owl population steadily declined by about 7 percent per year from 1990 through 2005. There are now less than half as many spotted owls in Washington as in the 1980s. In 1990, the spotted owl was listed as threatened under the federal Endangered Species Act.
In 1994, the Northwest Forest Plan created a system of late-successional reserves for nesting habitat for spotted owls throughout 24.5 million acres of federal lands in California, Oregon, and Washington. Despite this habitat protection on federal land, spotted owl numbers continue to decline, likely as a result of continued habitat loss on non-federal land and increasing competition with the barred owl (see Draft Recovery Plan for the Northern Spotted Owl (pdf)).
Surveys in the Watershed
The majority of old-growth forest in the watershed occurs in six distinct patches. Only four of these patches are considered large enough (greater than 1,000 acres) and at a low enough elevation (below 3,500 feet) to support breeding spotted owls.
Surveys for spotted and barred owls have been conducted in the Cedar River Watershed from 1986 to 2010. Because the surveys varied in extent, location, and focus (spotted vs. barred owls), it is difficult to compare the numbers of spotted or barred owls from year to year. It appears, however, that spotted owl numbers may be declining and barred owl numbers are increasing, mirroring state and regional trends.
All of the spotted owls were detected in old-growth forests in the upper watershed. A maximum of five spotted owls were found in surveys from 1986 to 1988. The first juvenile spotted owl documented in the watershed (which indicates successful breeding) was in 1990, and several other juveniles were observed in the early 1990s.
Complete surveys of all six large old-growth forest patches were conducted in 2005 and 2008. No spotted owls were found in 2005, and only a single male was found in 2008. He had previously been captured and banded as a juvenile in 2006 near Snoqualmie Pass. Although we have searched for him in 2009 and 2010, he was not relocated.
Barred owls were detected in many of the spotted owl surveys. Only four barred owls were found during extensive surveys throughout the watershed in 1985. In 2005 and 2006, a total of 38 barred owls were detected across the lower and upper watershed and in both old- and second-growth forest.
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- Cedar River Watershed Habitat Conservation Plan: Northern Spotted Owl – Measurements of Success
Other bird species in the watershed: