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Overview

Brief Summary

Description

Gray foxes are adept at climbing trees. They are active at night and during twilight, sleeping during the day in dense vegetation or secluded rocky places. Nursing mothers and pups use a den— a hollow log, abandoned building, tangle of brush, or cracked boulder—for shelter. When she is nursing small pups, the female stays within a few hundred meters of the den, but otherwise adults may range over a 2—5 square km area. Pups begin to forage on their own at about four months of age, and maintain close ties with the mother until they are about seven months old. By about ten months, both males and females are old enough to reproduce, and most females will have a litter annually from then on.

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  • Original description: "Schreber, J.C.D., 1775.  in Schreber's Die Säugthiere in Abbildungen nach der Natur mit Beschreibungen, Wolfgang Walther, Erlangen, 7 volumes, 1774-1846; 2(13):pl. 92[1775]; text: 3(21):361[1776]."
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Distribution

Range Description

The Grey Fox ranges from the southern edge of central and eastern Canada, and Oregon, Nevada, Utah and Colorado in the United States south to northern Venezuela and Colombia; and from the Pacific coast of the United States to the Atlantic and Caribbean oceans. The species is not found in the northern Rocky Mountains of the United States, or in the Caribbean watersheds of Honduras, Nicaragua, Costa Rica and western Panama.
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Geographic Range

Gray foxes are found in the lower half of the Nearctic and northwestern part of the Neotropics. More specifically, their range spans from southern Canada to Venezuela and Columbia, excluding portions of the Great Plains and mountainous regions of northwestern United States and eastern coast of Central America.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

  • Fritzell, E., K. Haroldson. 1982. Urocyon cinereoargenteus. Mammalian Species, 189: 1-8.
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occurs (regularly, as a native taxon) in multiple nations

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National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Global Range: Oregon, Nevada, Utah, and Colorado in the west and the U.S.-Canadian border in the east, south through Mexico and Central America to northern Colombia and Venezuela (Wozencraft, in Wilson and Reeder 1993). See Steers (1979 COSEWIC report) for information on distribution in Canada.

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Physical Description

Morphology

Physical Description

Fully grown gray foxes display a mix of white, red, black and gray fur. However, new born pups tend to be dark brown. Gray foxes are medium-sized canids with elongated bodies and relatively short legs. They usually weigh between 3 and 5 kg, but can weigh up to 9 kg. Individuals at high elevation are slightly larger than their low elevation counterparts. Males are slightly larger than females, and skeletal measurements show that males have longer pelvises and calcanea, wider scapulae and more robust limb bones. In general, gray foxes can grow up to 1 m in length. Their tail makes up approximately one-third of their total body length and has a distinct black stripe along the dorsal surface and a black tip. The top of the head, back, sides, and rest of the tail are gray with the belly, chest, legs and sides of the face being reddish brown. The cheeks, muzzle and throat are white. Gray foxes have oval-shaped pupils and the area around the eyes has a thin black stripe from the outside corner of the eye to the side of the head. Additionally, a thick black stripe runs from the inside corner of the eye, down the muzzle to the mouth. They are sometimes misidentified as red foxes (Vulpes vulpes); however, red foxes have slit-shaped eyes, larger feet, longer legs, and a leaner body.

Range mass: 2 to 9 kg.

Range length: 800 to 1125 mm.

Average length: 1000 mm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

  • Davis, W., D. Schmidly. 1994. "The Mammals of Texas - Online edition" (On-line). Common Gray Fox. Accessed March 29, 2009 at http://www.nsrl.ttu.edu/tmot1/uroccine.htm.
  • Postanowicz, R. 2008. "Lioncrusher's Domain" (On-line). Grey Fox. Accessed March 29, 2009 at http://www.lioncrusher.com/animal.asp?animal=18.
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Size

Length: 113 cm

Weight: 5900 grams

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Size in North America

Sexual Dimorphism: None

Length:
Range: 800-1,130 mm

Weight:
Range: 3-7 kg
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
In eastern North America, the Grey Fox is most closely associated with deciduous/southern pine forests interspersed with some old fields and scrubby woodlands (Hall 1981). In western North America, it is commonly found in mixed agricultural/woodland/chaparral/riparian landscapes and shrub habitats. The species occupies forested areas and thick brush habitats in Central America and forested montane habitats in South America (Eisenberg 1989). Grey Foxes occur in semi-arid areas of the southwestern USA and northern Mexico where cover is sufficient. They appear to do well on the margins of some urban areas (Harrison 1997).

Systems
  • Terrestrial
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Habitat

Gray foxes prefer to live in deciduous forests interspersed with brushy, woodland areas. Many populations thrive where woodlands and farmlands meet; however, red foxes (Vulpes vulpes) are known to frequent agricultural areas more than gray foxes. Proximity to water is a key feature of preferred habitat as well. Dens are usually located in hollow trees or logs, in crevices between and under large rocks, and in underground burrows. Dens have also been found in the lower forest canopy, 10 m above the forest floor, in hollow tree trunks and limbs. Gray foxes are the only member of the Canidae family that can climb trees. They are most often found below 3000 m in elevation.

Range elevation: 1000 to 3000 m.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: savanna or grassland ; forest ; scrub forest

  • Brant, S. 2002. "Gray Fox" (On-line). Accessed March 29, 2009 at http://www.blueplanetbiomes.org/grey_fox.htm.
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Comments: Often in woodland and shrubland in rough, broken country. Usually avoids open areas. May climb tree to avoid danger. Dens in cleft, small cave, hollow in tree or log, or debris pile; less frequently in burrow abandoned by other mammal.

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Migration

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

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Trophic Strategy

Food Habits

Gray foxes are omnivorous. Although they prey on small vertebrates, fruit and invertebrates also form a substantial part of their diet. Cottontails (Sylvilagus floridanus), mice (Peromyscus), woodrats (Neotoma), and cotton rats (Sigmodon hispidus) form the majority of their winter diet. In the Sonoran Desert, the fruit of the California palm makes up a significant portion of their winter diet. With the onset of spring, fruits become an increasingly important part of their diet, at times making up 70% of its diet. Invertebrates, fruits, nuts, and grains also increase in importance during the spring. Grasshoppers (Orthoptera), beetles (Coleoptera), and butterflies and moths (Lepidoptera) are the preferred invertebrates. When available, gray foxes may also feed on carrion. When gray foxes accumulate an excess amount of food, they cache it by digging a hole with their forepaws and burying it. Immediately afterwards, they mark it with urine or using their scent glands on their paws and tail in an effort to ward off other animals as well as to make it easier to relocate.

Animal Foods: birds; mammals; eggs; carrion ; insects; terrestrial non-insect arthropods

Plant Foods: roots and tubers; seeds, grains, and nuts; fruit

Foraging Behavior: stores or caches food

Primary Diet: carnivore (Eats terrestrial vertebrates, Insectivore , Scavenger ); herbivore (Frugivore , Granivore ); omnivore

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Comments: Opportunistic omnivore. Often chiefly depends on rabbits and other small mammals in winter, insects and fruit in summer. Overall diet may be dominated by plant material in some areas.

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Associations

Ecosystem Roles

Gray foxes have a small, but important role in our ecosystems. Their feeding habits allow them to influence small rodent (Rodentia) populations by maintaining a steady predator-prey relationship. They serve as a host to many parasitic arthropods, including fleas (Siphonaptera), lice (Phthiraptera), ticks (Ixodida), chiggers (Trombidiformes), and mites (Acari). Gray foxes are also host to a number of internal parasites including nematodes (Nematoda), flukes (Trematoda), tapeworms (Cestoda), and acanthocephalans (acanthocephala)

Commensal/Parasitic Species:

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Predation

Gray foxes primary predators include bobcats (Lynx rufus), golden eagles (Aquila chrysaetos), great-horned owls (Bubo virginianus) and coyotes (Canis latrans). In the southern region of the United States, gray fox abundance is highly dependent on coyote abundance. Other than death by natural causes, humans may be responsible for the greatest number of deaths and therefore may be their largest threat. Hunting, trapping and retaliatory killings by livestock ranchers are not uncommon. Unlike red foxes (Vulpes vulpes), which evade predators by using their superior agility, gray foxes escape by hiding under cover (e.g., brush piles). When escaping terrestrial predators, gray foxes can use their retractable claws to climb trees.

Known Predators:

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Known prey organisms

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General Ecology

Home range up to a few square miles in winter, less in summer (Richards and Hine 1953). Home ranges may or may not overlap. Probably reaches peak densities every 10 years. Probably averages around one family for every 4 square miles.

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Life History and Behavior

Behavior

Communication and Perception

Like other members of the family Canidae, gray foxes are able to communicate by barking and growling. Males have been observed trying to attract potential mates by raising their hind leg to show off their genitalia. As juveniles, gray foxes commonly play fight. As adults, they use their scent glands to mark territories and food sources.

Communication Channels: tactile ; acoustic ; chemical

Other Communication Modes: pheromones ; scent marks

Perception Channels: visual ; acoustic

  • Southwest Wildlife. 2007. "Southwest Wildlife" (On-line). The Gray Fox. Accessed March 29, 2009 at http://southwestwildlife.org/pdf/foxindepth.pdf.
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Cyclicity

Comments: Primarily crepuscular and nocturnal, but often active in daytime.

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Life Expectancy

Lifespan/Longevity

Lifespan for both captive and wild gray foxes ranges from 6 to 8 years. However, the oldest recorded wild gray fox was 10 years old at time of capture, and the oldest captive gray fox lived to be 12 years old.

Gray foxes generally live for 6 to 8 years. The oldest wild gray fox was 10 years old when captured. The oldest gray fox in captivity lived to be 12 years old.

Range lifespan

Status: wild:
6 to 10 years.

Range lifespan

Status: captivity:
6 to 12 years.

Typical lifespan

Status: wild:
6 to 8 years.

Typical lifespan

Status: captivity:
6 to 8 years.

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Lifespan, longevity, and ageing

Maximum longevity: 16.2 years (captivity)
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Reproduction

Reproduction

Gray foxes are solitary animals that socialize only during mating season. They are typically monogamous, although in rare cases polygamy and polyandry occur. For a short period of time after parturition, family groups consisting of male, female, and young exist. Male-female pairings form in the fall with breeding occurring in the winter. During October and September, attracting mates become more competitive and males usually display more aggression while retaining and defending mates. Similar to domestic dogs (Canis lupus familiaris), gray foxes have scent glands just inside the anus. Additional scent glands are found on their face and the pads of their feet. Although these glands are primarily used to demarcate territory, they may also be used to attract potential mates.

Mating System: monogamous

Breeding season varies with geographic region, elevation, and habitat quality. Breeding occurs in yearly cycles, beginning in January through late February, continuing into March. In some areas (e.g., Texas), breeding has been observed as early as December. Parturition occurs after about 2 months of gestation, peaking in April, with an average litter size of 3.8 pups, which weigh about 86 g at birth. Pups are typically weaned by 3 to 4 weeks, but may not be completely weaned until 6 weeks. Both genders are sexually mature by 10 months old, soon after dispersal. Annual onset of spermatogenesis occurs earlier and last longer than estrus. If they have been exposed to significant levels of the synthetic estrogen, diethylstilbestrol, females may experience delayed fertilization.

Breeding interval: Gray foxes breed once yearly.

Breeding season: December through March.

Range number of offspring: 1 to 7.

Average number of offspring: 3.8.

Range gestation period: 53 to 63 days.

Average gestation period: 59 days.

Range birth mass: 65 to 110 g.

Average birth mass: 86 g.

Range weaning age: 2 to 6 weeks.

Range time to independence: 10 to 17 months.

Average time to independence: 12 months.

Average age at sexual or reproductive maturity (female): 10 months.

Average age at sexual or reproductive maturity (male): 10 months.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Average number of offspring: 4.

Average age at sexual or reproductive maturity (male)

Sex: male:
365 days.

Average age at sexual or reproductive maturity (female)

Sex: female:
345 days.

Both genders take care of offspring in gray foxes. Before birth, males do a majority of the hunting, while females look for and prepare a suitable den. Weaning begins around 2 to 3 weeks of age. Pups begin eating solid food around 3 weeks old, which is primarily provided by the father. Parents teach pups how to hunt at around 4 months old. Until then, both parents prey for food separately, and pups practice their hunting skills by pouncing and stalking, which is primarily taught by the father. Pups depend on their parents for defense until about 10 months old, at which point they become sexually mature and disperse.

Parental Investment: precocial ; male parental care ; female parental care ; pre-hatching/birth (Provisioning: Male); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)

  • Brant, S. 2002. "Gray Fox" (On-line). Accessed March 29, 2009 at http://www.blueplanetbiomes.org/grey_fox.htm.
  • Fritzell, E., K. Haroldson. 1982. Urocyon cinereoargenteus. Mammalian Species, 189: 1-8.
  • Postanowicz, R. 2008. "Lioncrusher's Domain" (On-line). Grey Fox. Accessed March 29, 2009 at http://www.lioncrusher.com/animal.asp?animal=18.
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Breeds mainly in winter. Gestation lasts 51-63 days (average 53). Parturition occurs in April or May in the south-central U.S. Litter size averages 3-5. Parturition occurs March-April. Weaned in 8-10 weeks. Sexually mature within 1 year.

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Urocyon cinereoargenteus

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Species: 25
Species With Barcodes: 1

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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
Cypher, B.L., Fuller, T.K. & List, R.

Reviewer/s
Sillero-Zubiri, C. & Hoffmann, M. (Canid Red List Authority)

Justification
The Grey Fox is widespread in forest, woodland, brushland, shrubland, and rocky habitats in temperate and tropical regions of North America, and in northernmost montane regions of South America. There is no good evidence that Grey Fox numbers are increasing or decreasing in any part of their range. The species is not considered threatened at present.

History
  • 2004
    Least Concern
  • 1996
    Lower Risk/least concern
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Conservation Status

Gray foxes are abundant throughout most areas in the lower two-thirds of North America. They have no special conservation status at this time. Although they are trapped and hunted by humans, there does not appear to be any immediate threat.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

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National NatureServe Conservation Status

Canada

Rounded National Status Rank: N3 - Vulnerable

United States

Rounded National Status Rank: N5 - Secure

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NatureServe Conservation Status

Rounded Global Status Rank: G5 - Secure

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Population

Population
The species is common in occupied habitat, but appears to be restricted to locally dense habitats where it is not excluded by sympatric Coyotes (Canis latrans) and Bobcats (Lynx rufus) (Farias 2000b).

Population Trend
Stable
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Threats

Threats

Major Threats
Habitat loss, fragmentation, and degradation, may be particularly problematic in regions where human numbers are increasing rapidly and important habitat is converted for agricultural, industrial, and urban uses.

Because of its relatively lower fur quality compared with other species, commercial use of the Grey Fox is somewhat limited. However, 90,604 skins were taken in the United States during the 1991 and 1992 season (Linscombe 1994). In Mexico, Grey Foxes are frequently sold illegally as pets (R. List pers. comm.).
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Management

Conservation Actions

Conservation Actions
Not listed in the CITES Appendices. The Grey Fox is legally protected as a harvested species in Canada and the United States (Fritzell 1987).

Grey Foxes occur in numerous protected areas throughout their range, such as Big Bend NP, San Joaquin National Wildlife Refuge, Rocky Mountain NP and Everglades and Dry Tortugas NP, and Adirondack NP.

A number of foxes are held in captivity, although there may be more in the hands of private collections/individuals who do not report to ISIS. Grey Foxes appear to fare well in captivity and commonly are on display at zoos and wildlife farms.

Gaps in knowledge:
Because of the relatively high abundance and low economic value of Grey Foxes, surprisingly little research has been conducted on this species. Basic ecological and demographic information is needed for each of the major habitats occupied by Grey Foxes. Also, data on the response of Grey Foxes to human-altered landscapes (e.g., urban environments) is needed. No region-wide or range-wide population estimate has been produced. Furthermore, extremely little is known about the status and ecology of Grey Foxes outside of the USA and Canada. The effects of Grey Foxes on populations of smaller vertebrates, especially in urban and suburban settings without larger predators, may be important.
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Relevance to Humans and Ecosystems

Benefits

Economic Importance for Humans: Negative

Gray foxes are considered a problem species by poultry farmers. However, red foxes (Vulpes vulpes) are commonly misidentified as gray foxes, and commonly attack and kill poultry as well. In addition, gray foxes carry zoonotic diseases that could be a potential health threat to humans (e.g., rabies) and domestic dogs (Canis lupus familiaris; e.g., tularemia and canine distemper).

Negative Impacts: injures humans (causes disease in humans , carries human disease); causes or carries domestic animal disease

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Economic Importance for Humans: Positive

Gray foxes are hunted and trapped for their pelt. Compared to red fox (Vulpes vulpes), gray fox pelts are less desirable because the hairs are coarser and shorter. Gray foxes may also help control the abundance of certain agricultural pests, including rodents (Rodentia) and rabbits (Leporidae).

Positive Impacts: body parts are source of valuable material; controls pest population

  • Quinn, P. 2006. "Illinois Department of Natural Resources" (On-line). Accessed March 29, 2009 at http://www.dnr.state.il.us/orc/wildlife/furbearers/gray_fox.htm.
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Economic Uses

Comments: Trapped for pelt.

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Wikipedia

Gray fox

The gray fox (Urocyon cinereoargenteus) is a mammal of the order Carnivora ranging throughout most of[3] the southern half of North America from southern Canada to the northern part of South America (Venezuela and Colombia).[1] This species and the closely related Channel Island fox (Urocyon littoralis) are the only living members of the genus Urocyon, which is considered to be among the most primitive of the living canids.[4] Though it was once the most common fox in the east, and still is found there,[3][5][6] human advancement allowed the red fox to become more dominant. The Pacific States still have the gray fox as a dominant.

Contents

Origin

The gray fox appeared during the mid Pliocene epoch 3.6 million years ago (AEO) with the first fossil evidence found at the lower 111 Ranch site, Graham County, Arizona with contemporary mammals giant sloth, the elephant-like Cuvieronius, Large-headed llama, and the early small horses of Nannippus and Equus.[7] Genetic analyses of the fox-like canids confirmed that the gray fox is a distinct genus from the red foxes (Vulpes ssp.). Genetically, the gray fox often clusters with two other ancient lineages, the east Asian Raccoon dog (Nyctereutes procyonoides) and the African Bat-eared fox (Otocyon megalotis).[8] Chromosome number is 2n=66.[9] Recent genetic analysis has shown that the gray fox migrated into the northeastern United States post-Pleistocene in association with the Medieval Climate Anomaly warming trend.[10] The Channel Island fox is likely descended from mainland gray foxes.[11]

Description and behavior

Gray fox kit at the Palo Alto, California, Baylands
A yawning gray fox, northern Florida

The gray fox is mainly distinguished from most other canids by its grizzled upper parts, strong neck and black-tipped tail, while the skull can be easily distinguished from all other North American canids by its widely separated temporal ridges that form a U-shape. There is little sexual dimorphism, save for the females being slightly smaller than males. The gray fox ranges from 76 to 112.5 cm (30 to 44.3 in) in total length. The tail measures 27.5 to 44.3 cm (10.8 to 17.4 in) of that length and its hind feet measure 100 to 150 mm (3.9 to 5.9 in). The gray fox typically weighs 3.6 to 7 kg (7.9 to 15 lb), though exceptionally can weigh as much as 9 kg (20 lb).[12][13][14] It is readily differentiated from the red fox by the lack of "black stockings" that stand out on the latter. In contrast to all Vulpes and related (Arctic and fennec) foxes, the gray fox has oval (instead of slit-like) pupils.[15]

The gray fox's ability to climb trees is shared only with the Asian Raccoon dog among canids. Its strong, hooked claws allow it to scramble up trees to escape many predators such as the domestic dog or the coyote,[16] or to reach tree-bound or arboreal food sources. It descends primarily by jumping from branch to branch, or by descending slowly backwards as a house cat would do. The gray fox is nocturnal or crepuscular and dens in hollow trees, stumps or appropriated burrows during the day. Such gray fox tree dens may be located 30ft above the ground. [17] Prior to European colonization of North America, the red fox was found primarily in boreal forest and the gray fox in deciduous forest, but now the red fox is dominant in most of the eastern United States.[18] In areas where both red and gray foxes exist, the gray fox is dominant. [19]

Reproduction

Gray fox, showing black tail stripe, Sierra Nevada

The gray fox is monogamous. The breeding season of the gray fox varies geographically; in Michigan, the gray fox mates in early March, in Alabama, breeding peaks occur in February.[12] The gestation period lasts approximately 53 days. Litter size ranges from 1 to 7. Kits begin to hunt with their parents at the age of 3 months. By the time they are 4 months old, the kits will have developed their permanent dentition and can now easily forage on their own. The family group still remains together until autumn when the young reach sexual maturity and then disperse.

Diet

A gray fox at night
Adult male and female gray fox

The gray fox is a solitary hunter and is largely omnivorous. It frequently preys upon the eastern cottontail (Sylvilagus floridanus) in the eastern U.S., though it will readily catch voles, shrews, and birds. In California, the gray fox primarily eats rodents, followed by lagomorphs, e.g. jackrabbit, brush rabbit, etc.[16] In some parts of the Western United States (such as in the Zion National Park in Utah), the gray fox is primarily insectivorous and herbivorous. [20] Fruit is an important component of the diet of the gray fox and they seek whatever fruits are readily available, generally eating more vegetable matter than does the red fox (Vulpes vulpes).[12]

Subspecies

Gray fox skull

There are 16 subspecies recognized for the gray fox.[9] However, genetic analysis has not

See also

References

  1. ^ a b Wozencraft, W. Christopher (16 November 2005). "Order Carnivora (pp. 532-628)". In Wilson, Don E., and Reeder, DeeAnn M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3/browse.asp?id=14000841. 
  2. ^ Cypher et al. (2008). Urocyon cinereoargenteus. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 06 May 2008. Database entry includes justification for why this species is of least concern
  3. ^ a b Maine Trappers Association fur auctions. Mta.homestead.com (2005-12-17). Retrieved on 2011-09-15.
  4. ^ Robert K. Wayne, Eli Geffen, Derek J. Girman, Klaus P. Koepfli, Lisa M. Lau, Charles R. Marshall (1997). "Molecular Systematics of the Canidae". Systematic Biology 46 (4): 622–653. doi:10.1093/sysbio/46.4.622. PMID 11975336. 
  5. ^ "Sometimes confused with the red fox because of cinnamon-red fur on its sides, the gray fox is increasingly common in rich hardwood forests of the northeast.". Hikenewengland.com. Retrieved on 2011-09-15.
  6. ^ "Gray fox are widespread in Connecticut.". Wildlifeofct.com. Retrieved on 2011-09-15.
  7. ^ Paleobiology database, Collection 19656, Graham County, Arizona. Authority by the Dr. John Alroy, February 18, 1993.
  8. ^ E. Geffen, A. Mercure, D.J. Girman, D.W. Macdonald, R.K. Wayne (Sept. 1992). "Phylogenetic relationships of the fox-like canids: mitochondrial DNA restriction fragment, site and cytochrome b sequence analyses". Journal of Zoology, London 228: 27–39. doi:10.1111/j.1469-7998.1992.tb04430.x. 
  9. ^ a b Erik K. Fritzell, Kurt J. Haroldson (1982). "Urocyon cinereoargenteus". Mammalian Species. http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/pdf/i0076-3519-189-01-0001.pdf. Retrieved 2011-11-27. 
  10. ^ Christine A. Bozarth, Stacey L. Lance, David J. Civitello, Julie L. Glenn, and Jesus E. Maldonado (2011-04). "Phylogeography of the gray fox (Urocyon cinereoargenteus) in the eastern United States". Journal of Mammalogy: 283–294. http://si-pddr.si.edu/jspui/bitstream/10088/16136/1/vz_Bozarth_et_al_2011.pdf. Retrieved 2011-11-27. 
  11. ^ T.K. Fuller, B. L. Cypher (2004). C. Sillero-Zubiri, M. Hoffman, and D. W. Macdonald. ed. Gray fox Urocyon cinereoargenteus. pp. 92–97 in Canids: foxes, wolves, jackals, and dogs. Status survey and conservation action plan. Cambridge, United Kingdom: IUCN Publications. http://www.carnivoreconservation.org/files/actionplans/canids.pdf. Retrieved 2011-11-27. 
  12. ^ a b c "Urocyon cinereoargenteus". Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Urocyon_cinereoargenteus.html. Retrieved 2007-08-19. 
  13. ^ Boitani, Luigi, Simon & Schuster's Guide to Mammals. Simon & Schuster/Touchstone Books (1984), ISBN 978-0-671-42805-1
  14. ^ [1]
  15. ^ Alderton, David. Foxes, Wolves, and Wild Dogs of the World. London: Blandford, 1998. p122.
  16. ^ a b Fedriani, J. M.; Fuller, T. K.; Sauvajot, R. M. and York, E. C. (2000). "Competition and intraguild predation among three sympatric carnivores". Oecologia 125 (2): 258–270. doi:10.1007/s004420000448. 
  17. ^ Alderton, David. Foxes, Wolves, and Wild Dogs of the World. London: Blandford, 1998. p122.
  18. ^ Goddard-Taylor, Gayle (Winter 2005–2006). "The Silver Ghost: The life and times of the gray fox". Sanctuary: the Journal of the Massachusetts Audubon Society (Massachusetts Audubon Society) 45 (2): 13–15. 
  19. ^ Alderton, David. Foxes, Wolves, and Wild Dogs of the World. London: Blandford, 1998. p124.
  20. ^ Alderton, David. Foxes, Wolves, and Wild Dogs of the World. London: Blandford, 1998. p124.
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Names and Taxonomy

Taxonomy

Comments: Has been placed in the genus Canis or in the genus Vulpes by some authors (as recently as the 1970s). Urocyon cinereoargenteus and U. littoralis have been regarded as possibly conspecific by some authors; treated as distinct species by Jones et al. (1992) and Wozencraft (in Wilson and Reeder 2005).

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