The Biogeography of the Red Fox (Vulpes vulpes)
by Casey Cleve, student in Geography 316 Spring 2005
Thank you for visiting our site. This web pages was written by a student in Geography 316: Biogeography and edited by the instructor, Barbara Holzman, PhD. All photos and maps are posted with specific copyright permission for the express use of education on these web pages. The students have tried to be as accurate as possible with the information provided and sources and references are cited at the end of each page.
Species Name: Vulpes vulpes
and adaptation are one in the red fox – its most|
exquisite features are also some of its most important tools for survival”
J. David Henry
|Gerald and Buff Corsi © California Academy of Sciences (with permission)|
Description of Species:
The red fox Vulpes vulpes resembles a small dog with a long bushy tail, large pointed ears and a pointed muzzle. As these small canines’ name suggests, the red fox’s fur is typically a dark reddish-brown to a soft yellowish-red (Ables 1975). A variety of color variations exist. Some so-called red foxes have silver-tipped black fur (Grater 1978), which was sought after by the silver fox fur industry. This industry selectively bred red foxes to obtain the desired silver colored fur (Ables 1975). The most common color phase found within the Sierra Nevada is the ‘cross fox’, which is characterized by a black cross marking formed by two black stripes on its back; one across the shoulders and the other down the back (Grater 1978). Even with these color variations all red foxes have four common markings – white-tipped tails with white undersides and black feet and legs (Grater 1978). The average weight of males ranges from 4.5 -5.4kg and females’ range from 4.1-4.5kg (Ables 1975). Red foxes also have a distinctive skull because the sagittal crest comes to a point (Jameson & Peeters 1988). This is in contrast to the gray fox whose sagittal crests forms a lyre-shape (Jameson & Peeters 1988).
Red foxes have a large geographic distribution in North America, ranging over a significant portion of the continent from south of the ice sheet to north of Mexico (Ables 1975). Twelve subspecies exists within this geographic range (Figure 1). Within North American red foxes seldom inhabit semiarid grasslands, deserts, southeastern pine forest, and conifers forest along the Pacific Coast (Ables 1975). However, range extensions have been found in the western United States (Ables 1975).
The geographic range covering a majority of North America demonstrates the red foxes’ ability to inhabit a diverse variety of eco-regions and terrains (Ables 1975). For this reason, it is difficult to determine one type of suitable habitat. Studies have suggested that areas with abundant prey and ample cover are the most suitable habitats for the red fox, however these areas can exist in a variety of habitats (Zimen 1980, pp. 13).
|Figure 1 Geographic distribution of the 12 Red Fox Vulpes vulpes subspecies in North America (Ables 1975).|
For example, Vulpes vuples abeitorum that occur in British Columbia prefers mixed forest, meadow, and plains. In Alaska, Vulpes vulpes alascensis inhabit canyons, hillsides, and sides of valleys (Ables 1975). In southwestern Wisconsin dense populations of Vulpes vulpes regalis occur in mix of pastures, woodlots, cropland, and stream bottoms (Ables 1975).
The red fox populations that occur in western North America are made up of both indigenous and introduced populations (Burskirk & Zielinski 2003). In the western contiguous United States and British Columbia three indigenous subspecies occur, Vulpes vulpes macroura in Rocky Mountains, Vuples vuples cascadensis in Cascades, and Vulpes vulpes necator in Sierra Nevada, and one introduced subspecies the Vulpes vulpes fulvas. This subspecies occurs in the western lowlands, is an introduced subspecies indigenous to eastern United States (Burskirk & Zielinski 2003). The Vuples vuples fulva was brought to California during the fur trade industry (Burskirk & Zielinski 2003). While the indigenous subspecies have greatly declined, with Vulpes vulpes necator in the greatest decline; the introduced subspecies have increased in distributions (Burskirk & Zielinski 2003).
Adult red foxes have an approximate maximum home range of a 5-mile diameter and most foxes’ range is contained with in a 2-square mile area (Ables 1975). Home ranges vary based on seasonality, habitat complexity, and parturition. During winter months, home ranges are at the largest due to the difficulty of obtaining sufficient food (Ables 1975). During parturition and a few weeks following, red foxes have been observed to stay within a small .5-mile area of the den (Ables 1975).
The red fox diet consists mainly of rabbits, small rodents, wild berries and fruit, insects, and small birds (Ables 1975; Jameson & Peeters 1988). They are said to be ‘opportunistic feeders’ meaning that the amount of food consumed is dependent on supply (Ables 1975). Of the two subspecies present in California Vulpes vulpes necator and Vulpes vulpes fulva, the Vulpes vulpes necator inhabits the high elevations of the Sierra Nevada range, which provides significant seasonal differences that impact food supply. Because of this the fox’s diet varies based on the season (Grater 1978). During the summer months small rodents such as mice, chipmunks, ground squirrels, and pocket gophers are its preferred prey (Grater 1978). Insects such as grasshoppers and beetles are also in abundance at this time, providing another important food source (Grater 1978). In late summer to fall wild berries are bountiful and provide a large portion of the red fox’s diet. During the winter months when edible plants and berries are absent the red fox is completely dependent on catching and killing its food (Grater 1978). At this time, the fox is mainly dependent on the white-tail jackrabbit, the flying squirrel and the chickadee (Grater 1978). The red fox display clever hunting behaviors. They have been known to play dead to attract their prey and pounce up to 15 feet to make their attack (Voelker 1986, p 198).
The red fox can exist over a wide variety of terrain and vegetation types. The many subspecies habitat preferences vary from deep forest to patchwork of woodlots and croplands (Ables 1975). The two subspecies that exist within California prefer starkly different habitat characteristics. Vulpes vulpes necator lives in the Sierra Nevada above 1500 m while the Vulpes vulpes fulva inhabits California lowlands of the Sacramento Valley.
Gerald and Buff Corsi © California Academy of Sciences (with permission)
Breeding season begins in late fall to early winter (Ables 1975). Litters are born in early spring with a varying litter size from five to ten kits (Jameson & Peeters 1988). Kits first open their eyes at 9 days, emerge from the den at 1 month, and are weaned at about 2 months (Ables 1975). Males assist the females with providing solid food for the young (Jameson & Peeters 1988). The family stays together as a group until early fall when the pups are full-grown and dispersal occurs (Ables 1975).
The red fox Vulpes vulpes is a member of the Carnivora order. Morphologically, carnivores share several common characteristics (Feldhamer 2004, p 249). Every carnivore has elongated, well-developed canines, and carnassial teeth, which are used for slicing and shearing (Feldhamer 2004, p 249). The carnassial teeth are made up of the fourth upper premolar and the first bottom first molar. These teeth are particularly well developed in the Canidae family (Feldhamer 2004, p 249). Another characteristic that carnivores share are well-developed claws located on all digits (Feldhamer 2004, p 249). Members of the Canidae family, such as the red fox, have long limbs compared to body length and head size (Feldhamer 2004, p 249). They are also adapted to hunting prey in open environments (Feldhamer 2004, p 249).
The living Canidae family is separated into six groupings, the wolf-like canids, South American foxes, the vulpes-like canids, and three lineages that have distinct evolutionary histories, which include the raccoon dog, bat-eared fox, and grey fox (Figure 2) (Wang et al. 2004, pp 49). The red fox is in the vulpes-like category. The modern Canidae origin began approximately 10-12 million year ago, the divergence of the vulpes-like canids began 6 millions years ago (Wang et al. 2004, pp 49)
Figure 2 Consensus relationship tree (Wayne 2001).
The red fox’s biology may closely be associated with its choice of prey, which are small animals that easily startle and are quick in their reactions (Henry 1996, p 33). The physical characteristics of its prey contribute to the red fox’s solitaire hunter style (Henry 1996, p 33). The fox’s hunting strategy is to hunt quietly and stealthily; this enables it to sneak up on its prey with out alarming it. For this reason, the fox must hunt alone because if it hunted in packs it would easily frighten its prey (Henry 1996, p 33). The size of the prey also contributes to the fox’s solitary hunting style. The small prey size is only a large enough meal for one fox not an entire pack (Henry 1996, p 32).
Other ways the red fox is associated with its prey is that they are both crepuscular mammals, active at dawn and dusk (Henry 1996, p 32). This enables the fox to hunt during the time its prey are most active. The fox’s hearing abilities are also closely associated with its prey. The red fox’s ears have evolved to hear low deep tones, which match the same gnawing and rustling sound frequencies made by their prey (Henry 1996, p 32).
|Gerald and Buff Corsi © California Academy of Sciences (with permission)|
Other interesting issues:
In the mid-1980s the introduced subspecies Vulpes vulpes fulva was discovered in California (Lewis 1999). At this time, it became apparent that red foxes were residing outside their native geographic range because of predation evidence on endangered ground nesting birds such as the California clapper rail Rallus longirostris obsoletus, the light-footed clapper rail Rallus longirostris levipes and the California least tern Sterna antillarum browni (Lewis 1999). After these findings research was undertaken to determine the geographic range and density of this introduced subspecies. The current geographic range is that to be from Orange County to San Francisco Bay area. However, new sightings suggest that their range may be as far north as Sacramento (Lewis 1999). This large geographic range has been attributed to the distribution of fur trap locations (Lewis 1999). As fox populations increase there is concern that range expansion will occur (Lewis 1999).
Controlling these populations is important for endangered species protection; however, controlling population has become difficult due to current political climates and laws restricting typical control strategies, which have normally consisted of trapping and euthanasia (Lewis 1999). In 1990 legal action was taken against the U.S. Fish and Wildlife Service for its lethal control of foxes. In 1996, a law was passed that banned all body-gripping traps (Lewis 1999). As a result other management methods have been explored and undertaken. Current management strategies now focus on preventing fox introduction and translocation, educating the public on fox management issues, assessing fox population densities and distribution, and developing alternatives to the body-gripping traps to control fox populations (Lewis 1999).
1. Red foxes may vomit before fleeing to escape at a faster pace (Voelker 1986 p.201).
2. While hunting red foxes frequently backtrack to hide from predators. (Voelker 1986 p.201).
3. Red foxes can hop a vertical distance of 6 feet. (Voelker 1986 p.201).
4. Red foxes run through water to cover their scent when being chased. (Voelker 1986 p.201).
5. They can run up of 30 miles an hour (Voelker 1986 p.201).
Ables, E.D. 1975. “Ecology of the Red Fox in North America.” pp. 216-236. in M.W. Fox, eds. The Wild Canids. New York: Van Nostrand Reinhold Company. (Ables 1975)
Burskirk, S. W. and W. J. Zielinski. 2003. “Small and mid-sized carnivores.” pp. 207- 249. In C.J. Zabel and R.G. Anthony, eds. Mammal Community Dynamics: Management and Conservation in the Coniferous Forests of North America. United Kingdom: Cambridge University Press. (Burskirk & Zielinski 2003)
Feldhamer, G.A., L.C. Drickamer, S. H. Vessey, J.F. Merritt. 2004. Mammology: Adaptation, Diversity, and Ecology. Second Edition. McGrawHill Higher Education. Boston. (Feldhamer 2004)
Grater, R. L. 1978. Discovering Sierra Mammals. Sequoia Natural History Association and Yosemite Natural History Association. (Grater 1978)
Henry, J.D. 1996. Red Fox: The Catlike Canine. Smithsonian Institution Press. Washington, D.C. (Henry 1996)
Jameson Jr., E.W. and H. J. Peeters. 1988. California Mammals: California Natural History Guides: 52. Berkeley: University of California Press. (Jameson & Peeters 1988)
Lewis, J. C., K.L. Sallee, and R. T. Golightly, Jr. 1999. “Introduction and Range Expansion of Nonnative Red Foxes (Vulpes vuples) in California.” American Midland Naturalist, Vol. 142, 2 372-381. (Lewis 1999)
Voelker, W. 1986. The Natural History of Living Mammals. Plexus Publishing, Inc. Medford, NJ. (Voelker 1986)
Wang, X., R. H. Tedford, B. V. Valkenburgh, and R. K. Wayne. 2004. “Ancestory : Evolutionary history, molecular systematics, and evolutionary ecology Canidae” pp 40-56. in MacDonald, D. W., and C. Sillero-Zubiri. Biology and Conservation of Wild Canids. Oxford Univeristy Press, New York. (Wang et al. 2004, pp 49)
Wayne, K. R. 2001. Molecular Evolution of the Dog Family. Website assessed on 4/23/2005 http://www.grapevine.net/~wolf2dog/wayne2.htm (Wayne 2001)
Zimen, E. 1980. The Red Fox: Symposium on Behaviour and Ecology. Dr. W. Junk B.V. Publishers. The Hague-Boston-London 1980. (Zimen 1980)
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