Opinion ID: 3040620
Heading Depth: 3
Heading Rank: 2

Heading: Western Gray Squirrels in Washington

Text: Sciurus griseus griseus, a subspecies of the western gray squirrel,1 is the largest native tree squirrel in the Pacific Northwest. Status Review and 12-Month Finding for a Petition To List the Washington Population of the Western Gray Squirrel, 68 Fed. Reg. 34,628, 34,629 (June 10, 2003) (“Final Finding”). Members of the subspecies are “silvery-gray with dark flanks and creamy white underneath.” Id. They live in trees, rarely venture into open spaces, and subsist principally on acorn and nuts. Historically, the western gray squirrel was widespread throughout Washington, Oregon, California, and western Nevada. Id. at 34,630. Today, the western gray squirrel is fairly common in California, where it is a regulated game species, with an estimated population of eighteen million. Id. at 34,631. In Oregon, the subspecies is not rare and is legally hunted, but its distribution appears to be much reduced from historical levels. Id. at 34,632. In Nevada, the western gray squirrel is rare and has been classified as a “protected species” under state law. Id. at 34,631. In Washington, the western gray squirrel once ranged from the Puget Sound to the Columbia River, and from the Cascade Mountains to Lake Chelan. Id. at 34,632. The population has long been separated from the rest of the subspecies by the Columbia River. During the last century, its distribution has been reduced to three geographically isolated populations: the Puget Trough population, the North Cascades population, and the South Cascades population. The Puget Trough population, which is found near the 1 The two other subspecies are Sciurus griseus nigripes and Sciurus griseus anthonyi. Final Finding, 68 Fed. Reg. at 34,629. Only Sciurus griesus griesus is at issue here. 1222 NORTHWEST ECOYSTEM ALLIANCE v. USFWS Puget Sound, lives in a transitional ecological setting. Id. at 34,633. The population’s habitat of Oregon white oak woodlands is nestled between upland Douglas-fir forests and prairies. The habitat is wetter, flatter, and contains fewer mastproducing trees than the rest of the subspecies’ range. Consequently, the Puget Trough population is more dependent on the Oregon white oak for sustenance than populations in ecologically more diverse habitats. “Although the western squirrel was once common on the partially wooded prairies adjacent to the Puget Sound, the surviving Puget Trough population is now centered on Fort Lewis,” a military reservation. Id. “During intensive surveys in 1998 and 1999, only 6 western grey squirrels . . . were detected in over 4,000 hours of survey effort.” Id. Some researchers have concluded that the Puget Trough population is “at a high risk of extirpation.” Id. The North Cascades population is found in Chelan and Okanogan Counties. Id. at 34,632. Unlike the Puget Trough, the North Cascades habitat lacks oaks, the main source of winter foods for the western gray squirrel in most of its range. Id. at 34,635. Instead, the North Cascades population subsists on seeds and nuts produced by pine trees, big leaf maples, and English walnut trees. A survey in 2000 detected only three remnants out of the eighty-nine nests recorded in a 1996 survey, and found eighteen previously unreported nests. The reduced number of nests suggests a corresponding population decline. The South Cascades population, which constitutes the largest remaining population of western gray squirrels in Washington, is found in Skamania, Klickitat, and Yakima counties. Id. at 34,632, 34,634. One study has found western gray squirrels in Klickitat to have substantially larger body measurements than elsewhere in the subspecies’ range. Id. at 34,637. The study also concluded that the Klickitat population have substantially larger home range sizes and more nests per squirrel than elsewhere. Surveys in 2000 and 2001 produced population density estimates of 0.08-0.13 squirrel per hectare NORTHWEST ECOYSTEM ALLIANCE v. USFWS 1223 in the Klickitat Wildlife Area, as compared with 1.37 per hectare in Lake County, California, or with 2.47 per hectare in Yosemite Valley in California. Id. at 34,634.