page_title: Sierra Nevada red fox
section_title: Range
hierarchical_section_title: Sierra Nevada red fox / Range
caption_attribution_description: English: Sierra Nevada red fox makes first reappearance in Yosemite in nearly 100 years.
context_page_description: The Sierra Nevada red fox, also known as the High Sierra fox, is a subspecies of red fox and likely one of the most endangered mammals in North America. The fox's Sierra Nevada Distinct Population Segment is estimated at 29 adults near Sonora Pass in California. The Southern Cascades Distinct Population Segment consists of an estimated 42 adults near Lassen Volcanic National Park and an unknown number of individuals in five areas of Oregon. No other populations are known. Interbreeding with non-native red foxes and recruitment success are primary conservation concerns.
  The State of California banned trapping of Sierra Nevada red foxes in 1974 and listed the subspecies as threatened in 1980. The fox is a data gap species in Oregon and designated an Oregon sensitive species by the U.S. Forest Service. The Sierra Nevada Distinct Population Segment is listed as warranted but precluded under the Endangered Species Act. Listing of the Southern Cascades Distinct Population Segment was found to be not warranted.
context_section_description: Sierra Nevada red foxes are one of three fox subspecies in the montane clade of North America, occurring in the Cascade Mountains south of the Columbia River and California's Sierra Nevada range. Joseph Grinnell identified separated montane fox populations in the Oregon Cascades, Mount Shasta, Lassen Peak, 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 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.
  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 the winter of 2014-15, the Stanislaus National Forest in late 2015, and in Lassen Volcanic National Park 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.
  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 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.
  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 fox 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 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 system and highly specific mate selection.  A similar boundary may exist between Sierra Nevada red foxes and both the Sacramento Valley red fox and the introduced lowland foxes.
caption: Sierra Nevada red fox makes first reappearance in Yosemite in nearly 100 years.
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