Beaver in the Sierra Nevada
The North American beaver had a historic range that overlapped the Sierra Nevada in California. Before the European colonization of the Americas, beaver were distributed from the arctic tundra to the deserts of northern Mexico. The California Golden beaver subspecies was prevalent in the Sacramento and San Joaquin River watersheds, including their tributaries in the Sierra Nevada. Recent evidence indicates that beaver were native to the High Sierra until their extirpation in the nineteenth century.
Historical range and distribution
In 1916, Harold Bryant wrote in California Fish and Game, "The beaver of our mountain districts has been entirely exterminated and there are but a few hundred survivors to be found along the Sacramento, Colorado and San Joaquin Rivers." Earlier, in 1906, Frank Stephens wrote in "California Mammals" that Castor canadensis' historic range was from the "Pacific slope from Alaska to central California east to and including the Sierra Nevada and Cascade Mountains" and adds "In most parts of California the presence of beavers is only made known by the stumps of the trees and saplings that they have cut." McIntyre hypothesized that beaver were trapped out of the Sierra early in the nineteenth century by trappers before records could be kept. Other early twentieth century naturalists questioned whether the California Golden beaver dwelt above of elevation in the Sierra. In 2012, physical evidence demonstrated that beaver were native to the Sierra until at least the mid-nineteenth century, via radiocarbon dating of buried beaver dam wood uncovered by deep channel incision in two locations in Red Clover Creek in the Feather River watershed. That report was supported by a summary of indirect evidence of beaver including reliable observer accounts of beaver in multiple watersheds from the northern to the southern Sierra Nevada, including its eastern slope.Reintroduction to the Sierra
California Golden beaver taken from Snelling, California were stocked in 1940 at Mather Station west of Yosemite National Park and in 1944 at Fish Camp by the California Department of Fish and Game. These native "Central Valley" beaver have been building dams and rearing young successfully for 70 years in and near Yosemite at elevations higher than. A second reference confirms that the CDFG re-introductions of beaver into Mariposa County in the Merced River watershed were all C. C. subauratus taken from near sea level elevations. These lowland beaver adapted to the high Sierra without difficulty.Castor canadensis were re-introduced to the Tahoe Basin by the CDFG and the U. S. Forest Service between 1934 and 1949 in order to prevent stream degradation and to promote wetland restoration. Descended from no more than nine individuals from the Snake River in Idaho, 1987 beaver populations on the upper and lower Truckee River had reached a density of 0.72 colonies per kilometer.