Spring 2012 65 California Fish and Game 98(2):65-80; 2012 The historical range of beaver in the Sierra Nevada: a review of the evidence RICHARD B. LANMAN*, HEIDI PERRYMAN, BROCK DOLMAN, AND CHARLES D. JAMES Institute for Historical Ecology, 556 Van Buren Street, Los Altos, CA 94022, USA (RBL) Worth a Dam, 3704 Mt. Diablo Road, Lafayette, CA 94549, USA (HP) OAEC WATER Institute, 15290 Coleman Valley Road, Occidental, CA 95465, USA (BD) Bureau of Indian Affairs, Northwest Region, Branch of Environmental and Cultural Resources Management, Portland, OR 97232, USA (CDJ) *Correspondent:
[email protected] The North American beaver (Castor canadensis) has not been considered native to the mid- or high-elevations of the western Sierra Nevada or along its eastern slope, although this mountain range is adjacent to the mammal’s historical range in the Pit, Sacramento and San Joaquin rivers and their tributaries. Current California and Nevada beaver management policies appear to rest on assertions that date from the first half of the twentieth century. This review challenges those long-held assumptions. Novel physical evidence of ancient beaver dams in the north central Sierra (James and Lanman 2012) is here supported by a contemporary and expanded re-evaluation of historical records of occurrence by additional reliable observers, as well as new sources of indirect evidence including newspaper accounts, geographical place names, Native American ethnographic information, and assessments of habitat suitability. Understanding that beaver are native to the Sierra Nevada is important to contemporary management of rapidly expanding beaver populations. These populations were established by translocation, and have been shown to have beneficial effects on fish abundance and diversity in the Sierra Nevada, to stabilize stream incision in montane meadows, and to reduce discharge of nitrogen, phosphorus and sediment loads into fragile water bodies such as Lake Tahoe.