Sierra Nevada red fox (Vulpes vulpes necator)

Update September 2010...new siting of Sierra Nevada red fox living in Sonora Pass area! See story, below...

Threats

Red Fox The Sierra Nevada red fox is distinguished from members of the introduced lowland population of red foxes by its slightly smaller size and darker colored fur.  Red fox fur was sought after by trappers during the early part of last century because it was softer than California’s grey fox. Sierra Nevada populations have been reduced by grazing in meadows, which reduces prey populations, and by trapping, logging, and recreational disturbances. Human activities of any significant degree in areas of core habitat will certainly put pressure on this highly endangered species. Given the low numbers of the Sierra Nevada red fox and the increase of non-native red fox population, particularly in the Central Valley of California, competition from this non-native species is increasingly a concern for the Sierra Nevada subspecies.


Habitat

The range of the Sierra Nevada red fox is limited to the conifer forests and rugged alpine landscape of the Sierra Nevada and Cascade ranges between 4,000 feet and 12,000 feet. Preferred habitat for the Sierra Nevada red fox appears to be red fir and lodgepole pine forests in the subalpine zone and alpine fell-fields of the Sierra Nevada. Open areas are used for hunting, forested habitats for cover and reproduction. Edges are utilized extensively for tracking and stalking prey. The red fox hunts in forest openings, meadows, and barren rocky areas associated with its high elevation habitats. Found mostly above 6,000 feet in the summer months, Sierra Nevada populations were historically found in a variety of habitats, including alpine dwarf-shrub, wet meadow, subalpine conifer, lodgepole pine, red fir, aspen, montane chaparral, montane riparian, mixed conifer, and ponderosa pine. Jeffrey pine, eastside pine, and montane hardwood-conifer also are used. This species is known to inhabit vegetation types similar to those used by the marten and wolverine. The range of the Red fox is from the northern California Cascades eastward to the northern Sierra Nevada and then south along the Sierran crest to Tulare County.


Conservation

The current range and distribution of Sierra Nevada red fox is unknown.  Because of this and the scientific certainty of its hazardously low numbers, greater research is needed to ascertain the full extent of the red foxes range. Recent research conducted in the vicinity of Lassen Peak, has begun the process of understanding exactly how rare the native Sierra Nevada red fox is. This research conducted in the late 1990’s estimated that only 10-15 individuals were likely present in the Lassen Peak area--a number certainly low enough to cause concern over the possibility of localized extinction and highly endangered status throughout its historic range. Other historical evidence related to the Sierra Nevada red fox has led scientists to believe that it likely never occurred in large numbers.  From 1940 to 1959, 135 pelts were taken by trappers and that number shrunk down to 2 pelts a year by the 1970’s.  It is possible that red fox numbers were declining before these statistics were collected but in either case the Sierra Nevada red fox has certainly been in serious trouble for a very long time. The State of California banned red fox trapping in 1974.


Status

Until this summer (2010), the only known current population has been in the vicinity of Lassen Peak in Lassen Volcanic National Park, and also within Lassen National Forest. Periodic sightings have been reported by inexperienced observers throughout the rest of the Sierra Nevada but have not been documented by experts. In August, Forest Service biologists retrieved photographs from a bait station trail camera near Sonora Pass. DNA retrieved from saliva found on the tooth punctures in the bait bag was then analyzed by canid researchers Ben Sacks and Mark Statham at the UC Davis Veterinary Genetics Laboratory. Sacks and his colleagues confirmed that the DNA was from the rare Sierra Nevada red fox.

The Sierra Nevada red fox is genetically very distinct from red fox populations in coastal lowlands, the San Joaquin Valley and Southern California. These red foxes are derived from introduced foxes from the eastern United States (and Alaska). The Sacramento Valley subspecies is a genetically distinct native species, however.

The Sierra Nevada red fox is so uncommon that the California Fish and Game Commission declared it threatened in 1980 and it is considered critically endangered by the California Department of Fish and Game. The U.S. Forest Service, Pacific Southwest Research Station lists the Sierra Nevada red fox as a sensitive species.

According to a UC Davis press release, research from Sacks and his colleagues includes these findings to date:

  • There are native California red foxes still living in the Sierra Nevada.
  • The native red foxes in the Sacramento Valley (V.v. patwin) are a subspecies genetically distinct from those in the Sierra.
  • The two native California subspecies, along with Rocky Mountain and Cascade red foxes (V.v. macroura and V. v. cascadensis), formed a single large western population until the end of the last ice age, when the three mountain subspecies followed receding glaciers up to mountaintops, leaving the Sacramento Valley red fox isolated at low elevation.


Scientific Research

Aubry, K.B. 1983. The Cascade’s red fox: Distribution, Morphology, Zoogeography, and Ecology. PhD. Dissertation, University of Washington, Seattle, Washington. (1.26MB PDF)

Benson, J.F., et.al. 2005. Use of cover and response to cover type edges by female Sierra Nevada red foxes in winter. Western North American Naturalist 65: 127-130. (428KB PDF)

Perrine, J.D., 2005. Ecology of Red Fox (Vulpes vulpes) in the Lassen Peak Region of California U.S.A. Ph. D.Dissertation, University of California, Berkeley. 251 pp. (3MB PDF)

Perrine, J.D., et.al. 2007. Genetic evidence for the persistence of the critically endangered Sierra Nevada red fox in California. Conserv. Genetics. In press. (406KB PDF)


Supporting Resources

Press Release, UC Davis, September 3, 2010.

Press Release, US Forest Service September 2, 2010.

California Department of Fish and Game Natural History Information (URL) --This California state website contains rather limited and old information but is a good basic background composite for the species. Choose from a drop-down list to select the animal you are interested in.


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