American red fox
The American red fox, commonly known as the eastern American red fox, is a North American subspecies of the red fox. Historically, red foxes were classified as two species: Vulpes vulpes in Eurasia and Vulpes fulva in the Americas. Since 1959 they have been considered to be a singular species of Vulpes vulpes, with Vulpes vulpes fulvus one of the 10 North American subspecies. The American red fox differs from European forms by the greater breadth of its feet, its longer fur, noticeably shorter nose and ears, and its finer brush. According to hunters' accounts, they have less vigor and endurance in the chase compared to the European variant. Some authorities still give it full species status as Vulpes fulva. It is the largest of the true foxes and one of the most widely distributed members of the order Carnivora, occurring in North America. It is listed as least concern by the IUCN.
North American colonization and native status
Current literature discusses whether or not the red fox is native to North America, with some research suggesting that nearly all red fox populations in North America are not native. Vulpes Vulpes is usually seen either as an exotic species introduced by Europeans during the colonization of the North American continent or as a hybrid between Eurasian and native red foxes. While it is claimed that Vulpes vulpes fulvus stems from a nonnative population that spread westward from European introduction, a historical analysis of firsthand accounts does not support this claim.Phylogeographical and genetic analysis of the eastern American red fox suggests that foxes first migrated to North America during the Illinoian glaciation and spread southward More recently, the Wisconsin glaciation separated the North American fox population into two distinct areas. North American red foxes are genetically distinctive from their Eurasian counterparts. Despite claims of historical translocations from Europe, modern red fox populations in the United States’ southeastern region have been shown to be native to North America. DNA comparisons show that the eastern American red fox is closely related to native populations in Canada and the northeastern region of the United States and is therefore the result of natural range expansions and not an invasive species from Europe as was previously thought. Range expansions seen recently may be connected to anthropogenic landscape change and not the spread of exotic European varieties.
The native status of the eastern American red fox has been demonstrated by current research, which has important implications for management strategies. Previous classifications and taxonomic uncertainties frame populations of Vulpes vulpes fulvus as a nonnative, invasive species that can cause declines in the populations of native species, carrying capacities, and populate regions at higher densities. The identification of the origins of the North American red fox populations is crucial in conservation efforts aimed at native vs. nonnative species. Vulpes vulpes fulvus’s presence has been augmenting in the western U.S., an area in which it has not been shown to be native.
Taxonomy
The North American red foxes have been traditionally considered either as subspecies of Old World red foxes or subspecies of their own species, V. fulva. Due to the opinion that North American red foxes were introduced from Europe, all North American red foxes have been seen as conspecific with V. vulpes. However, genetic analyses of global red fox haplotypes by Statham et al. indicates that North American red foxes have been genetically isolated from Old World populations for 400,000 years, prompting possible application of V. fulva to all North American red foxes. Castello has formalized treatment of Vulpes fulva as a separate species from the nominate Vulpes vulpes from the Old World.Origin
Red foxes colonized the North American continent in two waves: during or before the Illinoian glaciation, and during the Wisconsinan glaciation. Gene mapping demonstrates that red foxes in North America have been isolated from their Old World counterparts for over 400,000 years, thus raising the possibility that speciation has occurred. In the far north, red fox fossils have been found in Sangamonian deposits in the Fairbanks District and Medicine Hat. Fossils dating from the Wisconsian are present in 25 sites in Arkansas, California, Colorado, Idaho, Missouri, New Mexico, Tennessee, Texas, Virginia, and Wyoming. Although they ranged far south during the Wisconsinan, the onset of warm conditions shrank their range toward the north, and they have only recently reclaimed their former American ranges because of human-induced environmental changes. Genetic testing indicates two distinct red fox refugia exist in North America, which have been separated since the Wisconsinan. The northern refugium occurs in Alaska and western Canada, and consists of the large subspecies V. v. alascensis, V. v. abietorum, V. v. regalis, and V. v. rubricosa. The southern refugium occurs in the sub-alpine parklands and alpine meadows of the Rocky Mountains, the Cascade Range, and the Sierra Nevada, and consists of the subspecies V. v. macroura, V. v. cascadensis, V. v. necator, and V. v. patwin. The latter clade has been separated from all other red fox populations since the last glacial maximum, and may possess unique ecological or physiological adaptations.Although European red foxes were introduced to portions of the United States in the 1900s, recent genetic investigation indicates an absence of European red fox haplotypes in any North American populations. Also, introduced eastern American red foxes have colonized southern California, the San Joaquin Valley, and the San Francisco Bay Area, but appear to have mixed with the Sacramento Valley red fox only in a narrow hybrid zone. In addition, no evidence is seen of interbreeding of eastern American red foxes in California with the montane Sierra Nevada red fox V. v. necator or other populations in the Intermountain West (between the Rocky Mountains to the east and the Cascade and Sierra Nevada ranges to the west.
Subspecies
Castello recognizes nine subspecies of the North American red fox, as listed below:| Subspecies | Trinomial authority | Description | Range | Synonyms |
| British Columbian fox Vulpes fulva abietorum | Merriam, 1900 | Generally similar to V. f. alascensis, but with a lighter, longer and more slender skull. | Interior of British Columbia and probably southeastern Alaska, US | sitkaensis |
| Northern Alaskan fox Vulpes fulva alascensis | Merriam, 1900 | A large, long-tailed, small-eared form with golden-fulvous fur. | Andreafsky Wilderness, Alaska, US | harrimani Merriam, 1900 kenaiensis Merriam, 1900 |
| Cascade Mountains red fox Vulpes fulva cascadensis | Merriam, 1900 | A short-tailed, small-toothed fox with yellow rather than fulvous fur; it is the subspecies most likely to produce "cross" color morphs. | Cascade Mountains, Skamania County, Washington, US | |
| Eastern American red fox Vulpes fulva fulva | Desmarest, 1820 | This is a small subspecies, with a smaller, sharper face, a shorter tail, a lighter pelt more profusely mixed with whitish and darker limbs. | Eastern Canada and eastern US | pennsylvanicus |
| Wasatch Mountains fox Vulpes fulva macroura | Baird, 1852 | This fox is similar to V. f. fulva, but with a much longer tail, larger hind feet, and more extensive blackening of the limbs. | Named for the Wasatch Mountains near the Great Salt Lake, Utah; found in the Rocky Mountains from Colorado and Utah, western Wyoming and Montana through Idaho north to southern Alberta | |
| Sierra Nevada red fox or High Sierra fox Vulpes fulva necator | Merriam, 1900 | Externally similar to V. f. fulva; it has a short tail, but cranially it is more like V. f. macroura. | High Sierra, California | |
| Sacramento Valley red fox Vulpes fulva patwin | Sacks et al., 2010 | Externally similar to V. f. fulva; it has a short tail, but cranially it is more like V. f. macroura. | Sacramento Valley, California | |
| Northern plains fox Vulpes fulva regalis | Merriam, 1900 | The largest North American red fox subspecies; it has very large and broad ears and a very long tail. It is a golden-yellow colour with pure black feet. | Elk River, Sherburne County, Minnesota, US | |
| Nova Scotia fox Vulpes fulva rubricosa | Bangs, 1898 | A large subspecies with a large, broad tail and larger teeth and rostrum than V. f. fulva; it is the deepest-coloured subspecies. | Digby, Nova Scotia, Canada | bangsi deletrix rubricos vafra |