The gray fox (''Urocyon cinereoargenteus''), or grey fox, is an

omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...

mammal of the family

Canidae Canidae (; from Latin, ''canis'', "dog") is a family (biology), biological family of dog-like carnivorans, colloquially referred to as dogs, and constitutes a clade. A member of this family is also called a canid (). There are three subfamily, ...

, widespread throughout North America and

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

. This species and its only congener, the diminutive island fox (''Urocyon littoralis'') of the California

Channel Islands The Channel Islands ( nrf, Îles d'la Manche; french: îles Anglo-Normandes or ''îles de la Manche'') are an archipelago in the English Channel, off the French coast of Normandy. They include two Crown Dependencies: the Bailiwick of Jersey ...

, are the only living members of the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

Urocyon ''Urocyon'' (Greek: "tailed dog") is a genus of Canidae which includes the gray fox (''Urocyon cinereoargenteus'') and the island fox (''Urocyon littoralis''). These two fox species are found in the Western Hemisphere. Whole genome sequencing ...

'', which is considered to be genetically

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

to all other living canids. Its

species name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bo ...

''cinereoargenteus'' means " ashen silver". It was once the most common

fox Foxes are small to medium-sized, omnivorous mammals belonging to several genera of the family Canidae. They have a flattened skull, upright, triangular ears, a pointed, slightly upturned snout, and a long bushy tail (or ''brush''). Twelv ...

in the eastern

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

, and though still found there, human advancement and

deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then land conversion, converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban area, urban ...

allowed the red fox to become the predominant fox-like canid. Despite this post-colonial competition, the gray fox has been able to thrive in urban and suburban environments, one of the best examples being southern Florida. The

Pacific States The West Coast of the United States, also known as the Pacific Coast, Pacific states, and the western seaboard, is the coastline along which the Western United States meets the North Pacific Ocean. The term typically refers to the contiguous U.S ...

and

Great Lakes region The Great Lakes region of North America is a binational Canada, Canadian–United States, American region that includes portions of the eight U.S. states of Illinois, Indiana, Michigan, Minnesota, New York (state), New York, Ohio, Pennsylvania ...

still have the gray fox as their prevalent

Etymology

The genus ''

'' comes from the Latin 'uro' meaning tail, and 'cyon', meaning dog. The species epithet ''cinereoargenteus'' is a combination of 'cinereo' meaning ashen, and 'argenteus' (from argentum), meaning 'silver', referencing the color of the tail.

Description

The gray fox is mainly distinguished from most other

canid Canidae (; from Latin, '' canis'', " dog") is a biological family of dog-like carnivorans, colloquially referred to as dogs, and constitutes a clade. A member of this family is also called a canid (). There are three subfamilies found withi ...

s by its grizzled upper parts, black stripe down its tail and strong neck, ending in a 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. Like other canids, the fox's ears and muzzle are angular and pointed. Its claws tend to be lengthier and curved. There is little

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...

, save for the females being slightly smaller than males. The gray fox ranges from in total length. The tail measures of that length and its hind feet measure . The gray fox typically weighs , though exceptionally can weigh as much as . The grey fox is readily distinguished from the red fox by its obvious lack of the "black stockings" that stand out on the red fox. The grey fox has a stripe of black hair that runs along the middle of its tail, and individual guard hairs that are banded with white, gray, and black. The gray fox displays white on the ears, throat, chest, belly, and hind legs. Gray foxes also have black around their eyes, on the lips, and on their noses. Urocyon cinereoargenteus grayFox cameo

In contrast to all ''

Vulpes '' Vulpes '' is a genus of the sub-family Caninae. The members of this genus are colloquially referred to as true foxes, meaning they form a proper clade. The word "fox" occurs in the common names of all species of the genus, but also appea ...

'' and related (Arctic and fennec) foxes, the gray fox has oval (instead of slit-like) pupils. The gray fox also has reddish coloration on parts of its body, including the legs, sides, feet, chest, and back and sides of the head and neck. The stripe on the fox's tail ends in a black tip as well. Their weight can be similar to that of a red fox, but gray foxes appear smaller because their fur isn't as long and they have shorter limbs. The dental formula of the ''U. cinereoargenteus'' is = 42.

Origin and genetics

Gray fox kit at the Baylands Bill Leikam 12-14-2011

The gray fox appeared in North America during the mid-

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58AEO) with the first fossil evidence found at the lower 111 Ranch site,

Graham County, Arizona Graham County is a county in the southeastern part of the U.S. state of Arizona. As of the 2020 census, the population was 38,533, making it the third-least populous county in Arizona. The county seat is Safford. Graham County composes the ...

with contemporary mammals like the giant sloth, the elephant-like '' Cuvieronius'', the large-headed llama, and the early small horses of '' Nannippus'' and ''

Equus Equus may refer to: * ''Equus'' (genus), a genus of animals including horses, donkeys and zebras * ''Equus'' (play), a play by Peter Shaffer * ''Equus'' (film), a film adaptation of the Peter Shaffer play * Equus (comics), a comic book characte ...

.'' Faunal remains at two northern California cave sites confirm the presence of the gray fox during the late

Pleistocene The Pleistocene ( , often referred to as the '' Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed ...

. 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. Genetic analyses of the fox-like canids confirmed that the gray fox is a distinct genus from the red foxes (''Vulpes'' spp.). The

'' is considered to be the most

of the living canids. Genetically, the gray fox often clusters with two other ancient lineages: The east Asian

raccoon dog The common raccoon dog (''Nyctereutes procyonoides''), also called the Chinese or Asian raccoon dog, is a small, heavy-set, fox-like canid native to East Asia. Named for its raccoon-like face markings, it is most closely related to foxes. Common ...

(''Nyctereutes procyonoides'') and the African

bat-eared fox The bat-eared fox (''Otocyon megalotis'') is a species of fox found on the African savanna. It is the only extant species of the genus ''Otocyon'' and considered a basal canid species. Fossil records indicate this canid first appeared during th ...

(''Otocyon megalotis''). The chromosome number is 66 (diploid) with a fundamental number of 70. The autosomes include 31 pairs of sub-graded subacrocentrics, but one only pair of metacentrics. Recent mitochondrial genetic studies suggests divergence of North American eastern and western gray foxes in the Irvingtonian mid-Pleistocene into separate sister taxa. The gray fox's dwarf relative, the island fox, is likely descended from mainland gray foxes. These foxes apparently were transported by humans to the islands and from island to island, and are descended from a minimum of 3–4

matrilineal Matrilineality is the tracing of kinship through the female line. It may also correlate with a social system in which each person is identified with their matriline – their mother's lineage – and which can involve the inheritance ...

founders.

Distribution and habitat

The species occurs throughout most rocky, wooded, brushy regions of the southern half of North America from southern

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tota ...

(

Manitoba , image_map = Manitoba in Canada 2.svg , map_alt = Map showing Manitoba's location in the centre of Southern Canada , Label_map = yes , coordinates = , capital = Win ...

through southeastern

Quebec Quebec ( ; )According to the Government of Canada, Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is ...

) to the northern part of

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the souther ...

(

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in ...

and Colombia), excluding the mountains of northwestern United States. It is the only canid whose natural range spans both North and South America. In some areas, high population densities exist near brush-covered bluffs.

Behavior

The gray fox is specifically adapted to climb trees. Its strong, hooked claws allow it to scramble up trees to escape many predators, such as the

domestic dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. Do ...

or the

coyote The coyote (''Canis latrans'') is a species of canine native to North America. It is smaller than its close relative, the wolf, and slightly smaller than the closely related eastern wolf and red wolf. It fills much of the same ecological ni ...

, or to reach tree-bound or arboreal food sources. It can climb branchless, vertical trunks to heights of 18 meters and jump from branch to branch. It descends primarily by jumping from branch to branch, or by descending slowly backwards like a

domestic cat The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...

. The gray fox is primarily

nocturnal Nocturnality is an ethology, animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatures generally have ...

crepuscular In zoology, a crepuscular animal is one that is active primarily during the twilight period, being matutinal, vespertine, or both. This is distinguished from diurnal and nocturnal behavior, where an animal is active during the hours of dayli ...

and makes its den in hollow trees, stumps or appropriated burrows during the day. Such gray fox tree dens may be located 30 ft above the ground. For the most part, they rest on the ground rather than higher up in trees. Prior to European colonization of North America, the red fox was found primarily in boreal forest and the gray fox in deciduous forest. With the increase in human populations in North America, their habitat selection has adapted: Gray foxes that live near human populations tend to choose areas near hardwood trees, locations used primarily by humans, or roads to utilize as their habitat. The increase of coyote populations around North America has reduced certain fox populations, so gray foxes have to choose a habitat that will allow them to escape the coyote threat as much as possible, hence the choice of habitat nearer to areas where humans are active. The larger predators of the gray fox, like coyotes and bobcats, tend to avoid human-use areas and paved roads, making this habitat useful for the gray fox. They heavily utilize the edges of forests as a travel corridor, which is used for primary movement from place to place. Their choices do not change based on sex, the season, or the time of day. They also do the majority of their hunting in edges, and use them to escape from predators as well. Gray foxes are thus known as an “edge species”.

Interspecies competition

Red Fox vs Grey Fox - San Joaquin National Wildlife Refuge

Gray foxes often hunt for the same prey as bobcats and coyotes who occupy the same region. To avoid interspecific competition, the gray fox has developed certain behaviors and habits to increase their survival chances. In regions where gray foxes and coyotes hunt for the same food, the gray fox has been observed to give space to the coyote, staying within its own established range for hunting. Gray foxes might also avoid their competitors by occupying different

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s than them. In California, gray foxes do this by living in

chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterrane ...

where their competitors are fewer and the low shrubbery provides them a greater chance to escape from a dangerous encounter. It also has been suggested that gray foxes could be more active at night than during the day to avoid their larger, diurnal competitors. Still, gray foxes frequently fall victim to bobcats and coyotes. When killed, the carcasses are often unconsumed, suggesting they are victims of intraguild predation. These gray foxes are often killed on or near the boundary of their established range, when they begin to interfere with their competitors. Gray foxes are known as mesopredators because they are mid-tier predators and their prey consists mostly of smaller mammals, while coyotes are known as de facto

apex predator An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic le ...

s due to the removal of other apex predators like wolves in North America. This explains the gray fox's tendency to change behavior in response to the coyote threat, as they are essentially lower on the food chain.

Reproduction

The gray fox is assumed to be

monogamous Monogamy ( ) is a form of dyadic relationship in which an individual has only one partner during their lifetime. Alternately, only one partner at any one time ( serial monogamy) — as compared to the various forms of non-monogamy (e.g., polyg ...

, like other foxes. The breeding season of the gray fox varies geographically; in

Michigan Michigan () is a U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the List of U.S. states and ...

, the gray fox mates in early March, in

Alabama (We dare defend our rights) , anthem = " Alabama" , image_map = Alabama in United States.svg , seat = Montgomery , LargestCity = Huntsville , LargestCounty = Baldwin County , LargestMetro = Greater Birmingham , area_total_km2 = 135,7 ...

, breeding peaks occur in February. The gestation period lasts approximately 53 days. Litter size ranges from 1–7, with a mean of 3.8 young per female. Gray Fox Kits

The sexual maturity of females is around 10 months of age. Kits begin to hunt with their parents at the age of 3 months. By the time that they are 4 months old, the kits will have developed their permanent dentition and can now easily forage on their own. The family group remains together until the autumn, when the young males reach sexual maturity, then they disperse. In a study of 9 juvenile gray foxes, only the males dispersed up to . The juvenile females stayed within proximity of the den within and always returned. On the other hand, adult gray foxes showed no signs of dispersion for either gender. The gray fox will typically live between six to ten years. The annual reproductive cycle of males has been described through epididymal smears and become fertile earlier and remain fertile longer than the fertility of females. Logs, trees, rocks, burrows, or abandoned dwellings serve as suitable den sites. Dens are used at any time during the year but mostly during whelping season. Dens are built in brushy or wooded regions and are better concealed than the dens of the red fox.

Diet

The gray fox is an

, solitary hunter. It frequently preys on the

eastern cottontail The eastern cottontail (''Sylvilagus floridanus'') is a New World cottontail rabbit, a member of the family Leporidae. It is the most common rabbit species in North America. Distribution The eastern cottontail can be found in meadows and shru ...

(''Sylvilagus floridanus'') in the eastern U.S., though it will readily catch

vole Voles are small rodents that are relatives of lemmings and hamsters, but with a stouter body; a longer, hairy tail; a slightly rounder head; smaller eyes and ears; and differently formed molars (high-crowned with angular cusps instead of lo ...

shrew Shrews (family Soricidae) are small mole-like mammals classified in the order Eulipotyphla. True shrews are not to be confused with treeshrews, otter shrews, elephant shrews, West Indies shrews, or marsupial shrews, which belong to diffe ...

s, and

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s. In California, the gray fox primarily eats rodents (such as deer mice, woodrats, and cotton rats), followed by lagomorphs, e.g. jackrabbit, brush rabbit, etc. When available, gray foxes may also feed on

carrion Carrion () is the decaying flesh of dead animals, including human flesh. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures ...

. 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. Fruit is an important component of the diet of the gray fox and they seek whatever

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in partic ...

s are readily available, generally eating more vegetable matter than does the red fox (''Vulpes vulpes''). Generally, there is an increase in fruits and invertebrates (such as grasshoppers,

beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

butterflies Butterflies are insects in the macrolepidopteran clade Rhopalocera from the order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The group comprises t ...

, and

moth Moths are a paraphyletic group of insects that includes all members of the order Lepidoptera that are not butterflies, with moths making up the vast majority of the order. There are thought to be approximately 160,000 species of moth, many of ...

s) within the gray fox's diet in the transition from winter to spring. As nuts, grains, and fruits become more numerous, they are cached by foxes. Typically, they attempt to cover the area with their scent either through their scent glands or urine. This marking serves the dual purpose of allowing them to find the food again later and preventing other animals from taking it.

Ecosystem role

Since woodrats, cotton rats, and mice make up a large part of the gray fox's diet, they serve as important regulators of small rodent populations. In addition to their beneficial predation on rodents, gray foxes are also less welcome hosts to some external and internal parasites, which include fleas, lice, nematodes, and tapeworms. In the United States, the most common parasite of the gray fox is a flea ('' Pulex simulans''); however, several new parasitic arthropods were found in populations in central Mexico, and a warming climate may encourage them to migrate north.

Hunting

Gray foxes are hunted in the U.S. The intensity of the hunting has correlated with the value of their

pelts 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 blanke ...

. Between the 1970–1971 and 1975–1976 hunting seasons, the price of gray fox pelts greatly increased and the number of individuals hunted jumped over six-fold from 26,109 to 163,458. It has been recently reported that over 500,000 gray foxes are killed every year for their fur.

Subspecies

There are 16 subspecies recognized for the gray fox. *''Urocyon cinereoargenteus borealis'' (New England) *''Urocyon cinereoargenteus californicus'' (southern California) *''Urocyon cinereoargenteus cinereoargenteus'' (eastern United States) *''Urocyon cinereoargenteus costaricensis'' (Costa Rica) *''Urocyon cinereoargenteus floridanus'' (Gulf states) *''Urocyon cinereoargenteus fraterculus'' (Yucatán) *''Urocyon cinereoargenteus furvus'' (Panama) *''Urocyon cinereoargenteus guatemalae'' (southernmost Mexico south to Nicaragua) *''Urocyon cinereoargenteus madrensis'' (southern Sonora, south-west Chihuahua, and north-west Durango) *''Urocyon cinereoargenteus nigrirostris'' (south-west Mexico) *''Urocyon cinereoargenteus ocythous'' (Central Plains states) *''Urocyon cinereoargenteus orinomus'' (southern Mexico, Isthmus of Tehuantepec) *''Urocyon cinereoargenteus peninsularis'' (Baja California) *''Urocyon cinereoargenteus scottii'' (south-western United States and northern Mexico) *''Urocyon cinereoargenteus townsendi'' (northern California and Oregon) *''Urocyon cinereoargenteus venezuelae'' (Colombia and Venezuela)

Parasites

Parasites of gray fox include trematode '' Metorchis conjunctus''. Other common parasites that were collected on gray foxes in Texas were a varity of tapeworms (''

Mesocestoides litteratus ''Mesocestoides'' is a genus of flatworms belonging to the family Mesocestoididae. The genus has cosmopolitan distribution. Species: *''Mesocestoides alaudae'' *''Mesocestoides ambiguus'' *''Mesocestoides angustatus'' *''Mesocestoides canisl ...

'', '' Taenia pisiformis'', '' Taenia serialis'') and roundworms ('' Ancylostoma caninum'', '' Ancylostoma braziliense'', ''

Haemonchus similis ''Haemonchus'' is a genus of nematodes belonging to the family Trichostrongylidae. They are abomasal parasites that cause anemia, followed by white eye disease. The genus has cosmopolitan distribution. Species: *''Haemonchus contortus'' *''H ...

'', '' Spirocerca lupi'', ''

Physaloptera rara Systematics ''Physaloptera'' is a genus of parasitic nematodes in the family Physalopteridae. Species include: *''Physaloptera dilatata''Muniz-Pereira et al., 2009, p. 11 *''Physaloptera dispar'' *''Physaloptera hispida''Kinsella, 1974, p ...

'', ''

Eucoleus aerophilus ''Eucoleus'' is a genus of nematodes belonging to the family Capillariidae. The genus has cosmopolitan distribution. Species: *'' Eucoleus aerophilus'' *'' Eucoleus annulatus'' *'' Eucoleus bacillatus'' *'' Eucoleus baskakowi'' *'' Eucole ...

''). ''T. pisiformis'' was the most common parasite species and was associated with frequent impacts on health.

References

External links

* * * {{Taxonbar, from=Q215250 Carnivorans of North America Carnivorans of South America

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 (biology), congener, the diminutive island fox ...

Mammals of the United States Mammals of Canada Carnivorans of Central America Mammals of Colombia Mammals of Mexico Mammals of Venezuela Fauna of northern South America Fauna of the Sierra Nevada (United States) Least concern biota of North America

Symbols of Delaware Fauna of California