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Beaver in the Sierra Nevada

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Abeaver lodgeinMcGee Creek,easternSierra Nevada,California.

TheNorth American beaver(Castor canadensis) had a historic range that overlapped theSierra NevadainCalifornia.Before theEuropean colonization of the Americas,beaver were distributed from thearctic tundrato the deserts of northernMexico.[1]The California Golden beaver subspecies (Castor canadensis subauratus) was prevalent in theSacramentoandSan Joaquin Riverwatersheds, 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

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A conifer felled bybeaveronMeeks Creek,Lake TahoeAugust, 2010

In 1916, Harold Bryant wrote inCalifornia 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,Coloradoand San Joaquin Rivers. "[2]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."[3]McIntyre hypothesized that beaver were trapped out of the Sierra early in the nineteenth century by trappers before records could be kept.[4]Other early twentieth century naturalists (Grinnell, Tappe, etc.) questioned whether the California Golden beaver dwelt above 1,000 feet (300 m) of elevation in the Sierra.[5][6]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 inRed Clover Creekin theFeather Riverwatershed.[7]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.[8]

Reintroduction to the Sierra

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North American beaveron the bank of the LowerKern River

California Golden beaver taken fromSnelling, California(elevation 256 ft or 78 m andWaterford, California(elevation 51 ft or 16 m) were stocked in 1940 at Mather Station (elevation 4,522 ft or 1,378 m) west ofYosemite National Parkand in 1944 atFish Camp(elevation 5,062 ft or 1,543 m) by theCalifornia Department of Fish and Game(CDFG). These native "Central Valley"beaver have been building dams and rearing young successfully for 70 years in and near Yosemite at elevations higher than 5,000 feet (1,500 m).[4]A second reference confirms that the CDFG re-introductions of beaver into Mariposa County in theMerced Riverwatershed were all C. C. subauratus (Golden beaver) taken from near sea level elevations.[9]These lowland beaver adapted to the high Sierra without difficulty.

Castor canadensiswere re-introduced to the Tahoe Basin by the CDFG and theU. S. Forest Servicebetween 1934 and 1949 in order to prevent stream degradation and to promote wetland restoration. Descended from no more than nine individuals from theSnake Riverin Idaho, 1987 beaver populations on the upper and lowerTruckee Riverhad reached a density of 0.72 colonies (3.5 beavers) per kilometer.[10]

Ecology

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Abeaver damonMeeks Creek,Lake TahoeAugust, 2010
Further information:Environmental impacts of beavers

As of 2023, theCalifornia Department of Fish and Gamerecognizes theecosystem servicesprovided by beavers across the state.[11]In cases where beavers are harming human property, the DFG will first attempt to educate the human party, and only then issue a limited permit to kill the beaver.[11]

Beaver have been documented in the upper and lowerTruckee River,Ward Creek,Cold Creek,Taylor Creek,Meeks Creek,Blackwood Creek,andKing's Beach,so the descendants of the original nine beavers have apparently migrated around most of Lake Tahoe.[12][13][14]A 2007 study of Taylor Creek showed that the beaver dam removal decreased wetland habitat, increased stream flow, and increased total phosphorus pollutants entering Lake Tahoe - all factors which negatively impact the clarity of the lake's water.[15]In addition, beaver dams located in Ward Creek, located on the west shore of Lake Tahoe, were also shown to decrease nutrients and sediments traveling downstream.[15]

Effects on aspen, cottonwood and willow

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In 1987, Beier reported that beaver had caused local extinction ofQuaking aspen(Populus tremuloides) andBlack cottonwood(Populus trichocarpa) on 4-5% of stream reaches on the lower Truckee River, howeverWillow(Salix spp.) showed good vigor despite heavy use in most reaches. He further speculated that without control of beaver populations that aspen and cottonwood could go extinct on the Truckee River.[16]However, not only have aspen and cottonwood survived ongoing beaver colonization but a recent study of ten Tahoe streams utilizing aerial multispectral videography has shown that deciduous, thick herbaceous, and thin herbaceous vegetation are more highly concentrated near beaver dams, whereas coniferous trees are decreased.[12]

Effects on salmonids

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Until recently, beaver were considered pests who caused flooding and impaired the passage of spawning trout and salmon. However, it has been shown that trout and salmon move freely across beaver dams.[17]The presence of beaver dams has also been shown to either increase the number of fish, their size, or both, in a study of brook, rainbow and brown trout inSagehen Creek,which flows into theLittle Truckee Riverat an altitude of 5,800 feet (1,800 m).[18]

See also

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References

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  1. ^Naiman, Robert J.;Johnston, Carol A.;Kelley, James C. (December 1988)."Alteration of North American Streams by Beaver"(PDF).BioScience.38(11): 753–762.doi:10.2307/1310784.JSTOR1310784.Archived fromthe original(PDF)on March 4, 2012.RetrievedFebruary 28,2010.
  2. ^Bryant, H.C. (1915).California's fur-bearing mammals.San Francisco, California: State of California, Resources Agency, Dept. of Fish and Game. p. 96.RetrievedMarch 17,2010.
  3. ^Stephens, Frank (1906).California Mammals in West Coast Nature Series.San Diego, California: The West Coast Publishing Company. p.97.RetrievedJune 19,2010.
  4. ^abMcIntyre, Robert N. (April 1948)."A New Park Resident"(PDF).Yosemite Nature Notes.RetrievedJanuary 23,2010.
  5. ^Grinnell, Joseph; Dixon, Joseph S.; Linsdale, Jean M. (1937).Fur-Bearing Mammals of California: Their Natural History, Systematic Status and Relations to Man.Berkeley, California: University of California Press. p. 636.ISBN978-0-7812-5041-2.
  6. ^Tappe, Donald T. (1942)."The Status of Beavers in California"(PDF).Game Bulletin No. 3.California Department of Fish & Game. Archived fromthe original(PDF)on July 27, 2011.RetrievedApril 11,2010.
  7. ^James, C.D.; Lanman, R.B. (Spring 2012)."Novel physical evidence that beaver historically were native to the Sierra Nevada"(PDF).California Fish and Game.98(2): 129–132.
  8. ^Lanman, RB; Perryman, H; Dolman, B; James, CD (Spring 2012)."The historical range of beaver in the Sierra Nevada: a review of the evidence"(PDF).California Fish and Game.98(2): 65–80.
  9. ^Hensley, Arthur L. (1946)."A Progress Report on Beaver Management in California".California Fish and Game.32(2):87–99.RetrievedMarch 26,2010.
  10. ^Beier, Paul; Barrett, Reginald H (1989)."Beaver Distribution in the Truckee River Basin, California"(PDF).California Fish and Game.Archived fromthe original(PDF)on July 20, 2011.RetrievedJanuary 17,2010.
  11. ^ab"Beaver Depredation Policy in California".California Department of Fish and Wildlife. June 5, 2023. Departmental Bulletin 2023-02.
  12. ^abAyers, Michael Benson (October 1997).Aerial Multispectral Videography for Vegetation Mapping and Assessment of Beaver Distribution within Selected Riparian Areas of the Lake Tahoe Basin(Thesis). University of Nevada at Reno. p. 71. Archived fromthe originalon July 20, 2011.RetrievedAugust 26,2010.
  13. ^"The Beavers of the Truckee River".Tahoe Arts and Mountain Culture. July 20, 2009. Archived fromthe originalon June 9, 2011.RetrievedJanuary 19,2010.
  14. ^Van Lom, Keaven (January 16, 2010)."This is Wildlife Management in the 21st Century?".Moonshine Ink. Archived fromthe originalon March 3, 2012.RetrievedJanuary 17,2010.
  15. ^abMuskopf, Sarah (October 2007).The Effect of Beaver (Castor canadensis) Dam Removal on Total Phosphorus Concentration in Taylor Creek and Wetland, South Lake Tahoe, California(PDF)(Thesis). Humboldt State University, Natural Resources.hdl:2148/264.
  16. ^Beier, Paul; Barrett, Reginald H. (October 1987). "Beaver Habitat Use and Impact in Truckee River Basin, California".Journal of Wildlife Management.51(4): 794–799.doi:10.2307/3801743.JSTOR3801743.
  17. ^Pollock, Michael M.; Heim, Morgan; Werner, Danielle (2003)."Hydrologic and geomorphic effects of beaver dams and their influence on fishes"(PDF).American Fisheries Society Symposium.37:213–233. Archived fromthe original(PDF)on July 7, 2011.RetrievedJanuary 17,2010.
  18. ^Gard, R (1961). "Effects of beaver on trout in Sagehen Creek, California".Journal of Wildlife Management.25(3): 221–242.doi:10.2307/3797848.JSTOR3797848.
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