The Sierra Nevada red fox (''Vulpes vulpes necator''), also known as the High Sierra fox, is a subspecies of
red fox found in the
Oregon Cascades and the
Sierra Nevada. It is likely one of the most endangered mammals in North America. The High Sierra fox shares most of its physical characteristics with the red fox, though it is slightly smaller and has some special adaptions for travel over snow. The High Sierra fox was discovered as a subspecies in 1937, but its study lapsed for more than half a century before its populations were rediscovered beginning in 1993. This subspecies of red fox may live up to 6 years.
Description
Like other montane foxes, Sierra Nevada red foxes are somewhat smaller and lighter in weight than lowland North American red foxes. Their
fur
Fur is a thick growth of hair that covers the skin of mammals. It consists of a combination of oily guard hair on top and thick underfur beneath. The guard hair keeps moisture from reaching the skin; the underfur acts as an insulating blanket t ...
may be
red, cross, or silver phase with the red phase having the greyish-blonde coloration characteristic of montane foxes.
All three phases occur in the Oregon Cascade and Sonora Pass populations, but only red phase individuals have been found in the Lassen population. Their foot pads are fur-covered, a common adaptation to travel over snow. Sierra Nevada red foxes are relatively long-lived compared to other red foxes, typically living five to six years. Non-invasively monitored females have either not bred or bred a minority of years.
Research
Discovery and Rediscovery
Sierra Nevada red foxes are one of three fox subspecies in the
montane clade of North America, occurring in the
Cascade Mountains
The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, a ...
south of the
Columbia River and
California
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
's
Sierra Nevada range.
Joseph Grinnell
Joseph Grinnell (February 27, 1877 – May 29, 1939) was an American field biologist and zoologist. He made extensive studies of the fauna of California, and is credited with introducing a method of recording precise field observations known as ...
identified separated montane fox populations in the Oregon Cascades,
Mount Shasta
Mount Shasta ( Shasta: ''Waka-nunee-Tuki-wuki''; Karuk: ''Úytaahkoo'') is a potentially active volcano at the southern end of the Cascade Range in Siskiyou County, California. At an elevation of , it is the second-highest peak in the Cascades ...
,
Lassen Peak
Lassen Peak ( ), commonly referred to as Mount Lassen, is a lava dome volcano and the southernmost active volcano in the Cascade Range of the Western United States. Located in the Shasta Cascade region of Northern California, it is part of the ...
, and
Sierra Nevada in 1937.
Study then lapsed for approximately 60 to 75 years, depending on location. Rediscovery of the Lassen population began in 1993
followed by detection of a Sierra Nevada population at
Sonora Pass
Sonora Pass (el. 9,624 ft. / 2,933 m.) is a mountain pass in the Sierra Nevada in California. It is the second-highest in California and in the Sierra Nevada. lower by 321 ft. (about 98 m.) than Tioga Pass to the south. State Route 108 ...
in 2010
and rediscovery of the Oregon Cascades population began in 2011. The Lassen and Sonora Pass populations are isolated from each other and it is unknown if a population remains at Mount Shasta.
Sacramento Valley Red Fox
Genetic studies beginning in 2010 have also shown the Sacramento Valley red fox (''Vulpes vulpes patwin'') is a distinct subspecies more closely related to the Sierra Nevada red fox than introduced lowland red foxes present in the rest of California.
A relatively restricted and narrow hybrid zone between Sacramento Valley red and non-native foxes has been stable for several decades, despite the five-fold expansion of non-native red fox populations throughout the rest of lowland and coastal California. This may be due to the foxes' monogamous mating habits and highly specific mate selection. A similar genetic boundary may exist between Sierra Nevada red foxes and both the Sacramento Valley red fox and the introduced lowland foxes.
Distribution and Habitat
Range
The extent of the Sierra Nevada red fox populations is an area of active research. In Oregon, ongoing studies at Mount Hood and Central Oregon were prompted by observations in 2012 and 2013. Recent genetic evidence also suggests range expansion into western Oregon since the 1940s.
In California, detections occurred in northern
Yosemite National Park
Yosemite National Park ( ) is an American national park in California, surrounded on the southeast by Sierra National Forest and on the northwest by Stanislaus National Forest. The park is managed by the National Park Service and covers an ...
the winter of 2014-15, the
Stanislaus National Forest in late 2015, and in
Lassen Volcanic National Park
Lassen Volcanic National Park is an American national park in northeastern California. The dominant feature of the park is Lassen Peak, the largest plug dome volcano in the world and the southernmost volcano in the Cascade Range. Lassen Vol ...
in 2018. The first two areas are near Sonora Pass, but it has not been confirmed the individuals are part of the Sonora Pass population.
Habitat Altitude
Elevations occupied by the Sierra Nevada red fox are also an area of current research. Oregon detections have occurred between 4900 and 6500 feet, though observations of
Cascade red fox in
Washington
Washington commonly refers to:
* Washington (state), United States
* Washington, D.C., the capital of the United States
** A metonym for the federal government of the United States
** Washington metropolitan area, the metropolitan area centered o ...
suggest lower elevations may be accessed during
dispersal. John Perrine's study on Lassen Peak, using 144 baited motion-sensitive cameras from 1997 to 2002, found no foxes below 4520 feet.
Historically, Grinnell's 1937 survey found occurrence from 4500 to 11,500 feet in California.
The fox was initially described in 1906 as occurring above 6000 feet in the high Sierra.
Diet
A 2005 study of the then remnant population surviving on Mount Lassen found that the foxes are nocturnal hunters whose diet is predominantly mammals, especially rodents and
mule deer
The mule deer (''Odocoileus hemionus'') is a deer indigenous to western North America; it is named for its ears, which are large like those of the mule. Two subspecies of mule deer are grouped into the black-tailed deer.
Unlike the related whi ...
, supplemented by birds, insects and
pinemat manzanita berries as seasonally available.
Lagomorphs (hares, rabbits and pikas) were virtually absent from the foxes' diet.
Status and conservation
![Redfox - Flickr - USDAgov](https://upload.wikimedia.org/wikipedia/commons/e/ef/Redfox_-_Flickr_-_USDAgov.jpg)
Documented trapping of the Sierra Nevada red fox may have begun when
Moses Schallenberger
Moses hbo, מֹשֶׁה, Mōše; also known as Moshe or Moshe Rabbeinu (Mishnaic Hebrew: מֹשֶׁה רַבֵּינוּ, ); syr, ܡܘܫܐ, Mūše; ar, موسى, Mūsā; grc, Mωϋσῆς, Mōÿsēs () is considered the most important pro ...
of the
Stephens-Townsend-Murphy Party spent the winter of 1844-45 at
Donner Pass
Donner Pass is a mountain pass in the northern Sierra Nevada, above Donner Lake and Donner Memorial State Park about west of Truckee, California. Like the Sierra Nevada themselves, the pass has a steep approach from the east and a gradual appr ...
, taking an average of one red fox every two days. Red fox fur was sought after by trappers during the early part of the 20th century because it was softer than that of California’s
gray fox
The gray fox (''Urocyon cinereoargenteus''), or grey fox, is an omnivorous mammal of the family Canidae, widespread throughout North America and Central America. This species and its only congener, the diminutive island fox (''Urocyon littor ...
(''Urocyon cinereoargenteus'').
The State of California banned trapping of Sierra Nevada red foxes in 1974 and listed the subspecies as threatened in 1980.
The fox's
Sierra Nevada Distinct Population Segment {{no footnotes, date=February 2018
A distinct population segment (DPS) is the smallest division of a taxonomic species permitted to be protected under the U.S. Endangered Species Act. ''Species'', as defined in the Act for listing purposes, is a ...
is estimated at 29 adults near
Sonora Pass
Sonora Pass (el. 9,624 ft. / 2,933 m.) is a mountain pass in the Sierra Nevada in California. It is the second-highest in California and in the Sierra Nevada. lower by 321 ft. (about 98 m.) than Tioga Pass to the south. State Route 108 ...
in
California
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
. The
Southern Cascades Distinct Population Segment consists of an estimated 42 adults near
Lassen Volcanic National Park
Lassen Volcanic National Park is an American national park in northeastern California. The dominant feature of the park is Lassen Peak, the largest plug dome volcano in the world and the southernmost volcano in the Cascade Range. Lassen Vol ...
and an unknown number of individuals in five areas of
Oregon
Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...
.
No other populations are known. Interbreeding with non-native red foxes and
recruitment success are primary conservation concerns.
The fox is a data gap species in Oregon
and designated an Oregon sensitive species by the U.S. Forest Service.
Listing of the Southern Cascades Distinct Population Segment was found to be not warranted.
The Sierra Nevada Distinct Population Segment was listed under the
Endangered Species Act in 2021.
Origin
The three subspecies in the montane clade separated after the
Wisconsin glaciation
The Wisconsin Glacial Episode, also called the Wisconsin glaciation, was the most recent glacial period of the North American ice sheet complex. This advance included the Cordilleran Ice Sheet, which nucleated in the northern North American Cord ...
, 15 to 20,000 years ago,
with the
Columbia River perhaps dividing the Cascade and Sierra Nevada red foxes. However, prior to 2010, montane red foxes in Oregon were presumed to be the Cascade red fox.
Earlier literature therefore indicates incorrect ranges for the Cascade and Sierra Nevada red fox.
References
External links
Ben Sacks Lecture on Sacramento Valley and Sierra Nevada Red Fox, 2014Report Sierra Nevada red fox sightings to the California Department of Fish and Game
{{Taxonbar, from=Q7511533
Vulpes
Endemic fauna of the United States
Fauna of the Sierra Nevada (United States)
Mammals of the United States
Carnivorans of North America
Fauna of California
Fauna of the Western United States