DistributionRead full entry
Global Range: The historical range has been described as including California, Oregon, Washington, and part of southern British Columbia (Hall 1981). However, patterns of genetic variation (Schwartz et al. 2007) are inconsistent with this distribution and instead indicate that the historical population in California was differentiated to some degree from populations farther north.
According to Schempf and White (1977), the historical range in California apparently extended from Del Norte and Trinity counties eastward through Siskiyou and Shasta counties, and southward through the Sierra Nevada to Tulare County; reported elevational range was 1,600-14,200 feet, and the mean of 143 sightings was about ,8000 feet (California DF&G 1990). However, the basis for this range includes many anecdotal records of questionable validity. Aubry et al. (2007) mapped the distribution based on verifiable and documented occurrence records and found that wolverine distribution in California included only the central and southern Sierra Nevada. A large gap existed between the central Sierra Navada records and the nearest locations to the north in Oregon (Aubry et al. 2007).
Until recently, there had been no confirmed records of wolverine in California since 1922 (Grinnell et al. 1937); attempts to locate wolverines by means of photographic bait stations during the winters of 1991-1992 and 1992-1993 yielded no records (Barrett et al. 1994). In 2008-2010, a single male wolverine was photographed by camera traps in the central Sierra Nevada of California. However, genetic data (Moriarty et al. 2009) indicate that this male is related to wolverines in the western Rocky Mountains and not a remnant of the native California population, so the native population in California remains as apparently extirpated.
Aubry et al. (2007) found no verifiable or documented post-1994 occurrence records in Oregon, but several records were available for 1995-2005 in the northern half of Washington. More recently, a wolverine was photographed at a baited camera trap in the Cascade Mountain of southern Washington (Mount Adams).
In the 1960s and 1970s, wolverines began showing up in low-elevation, nonforested habitats in eastern Washington and Oregon (Aubry et al. 2007). Verts and Carraway (1998) and Aubry et al. (2007) believed that the "anomalous wolverine records in eastern Washington and Oregon during that time probably represent dispersals from Canada or Montana that failed to establish resident populations" (Aubry et al. 2007).