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

omnivorous An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize ...

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

of the family

Canidae Canidae (; from Latin, ''canis'', "dog") is a family (biology), biological family of caniform carnivorans, constituting a clade. A member of this family is also called a canid (). The family includes three subfamily, subfamilies: the Caninae, a ...

, widespread throughout

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

and

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

. This species and its only congener, the diminutive

island fox The island fox (''Urocyon littoralis'') is a small fox species that is endemic to six of the eight Channel Islands of California. Evolved from their mainland gray fox (''U. cinereoargenteus'') recent and larger ancestor, they diversified into ...

(''Urocyon littoralis'') of the California

Channel Islands The Channel Islands are an archipelago in the English Channel, off the French coast of Normandy. They are divided into two Crown Dependencies: the Jersey, Bailiwick of Jersey, which is the largest of the islands; and the Bailiwick of Guernsey, ...

, are the only living members of the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

'' Urocyon'', which is considered to be genetically

sister A sister is a woman or a girl who shares parents or a parent with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to ref ...

to all other living canids. Its

species name In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...

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

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, and though still found there, human advancement and

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

allowed the

red fox The red fox (''Vulpes vulpes'') is the largest of the true foxes and one of the most widely distributed members of the order Carnivora, being present across the entire Northern Hemisphere including most of North America, Europe and Asia, plus ...

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 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. states of Calif ...

and

Great Lakes region The Great Lakes region of Northern America is a binational Canadian– American region centered on the Great Lakes that includes the U.S. states of Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania, and Wisconsin and the Ca ...

still have the gray fox as their prevalent fox.

Etymology

The genus '' Urocyon'' comes from Ancient Greek οὐρά (ourá, “tail”) + κύων (kúōn, “dog”). The species epithet ''cinereoargenteus'' is a combination of 'cinereo' (from 'cinereus') 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 family (biology), biological family of caniform carnivorans, constituting a clade. A member of this family is also called a canid (). The family includes three subfamily, subfamilies: the Caninae, a ...

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 sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

, 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 large individuals can weigh as much as . The gray fox is readily distinguished from the

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 hair Guard hair or overhair is the outer layer of hair of most mammals, which overlay the fur. Guard hairs are long and coarse and protect the rest of the pelage (fur) from abrasion and frequently from moisture. They are visible on the surface of the ...

s 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 the species in genus ''

Vulpes '' Vulpes '' is a genus of the subfamily 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 appears in ...

'', such as the

, 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. Its weight can be similar to that of a red fox, but the gray fox appears smaller because its

fur A fur is a soft, thick growth of hair that covers the skin of almost all 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 ...

is not as long and it has shorter limbs. The

dental formula Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology ...

of ''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 (geology), epoch in the geologic time scale that extends from 5.33 to 2.58AEO) with the first fossil evidence found at the lower 111 Ranch site, Graham County, Arizona with contemporary mammals like the giant sloth, the elephant-like '' Cuvieronius'', the large-headed llama, and the early small horses of '' Nannippus'' and '' Equus.'' Faunal remains at two northern California cave sites confirm the presence of the gray fox during the late

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

. 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

'' Urocyon'' is considered to be

to the other living canid taxa. Genetically, the gray fox often clusters with two other ancient lineages: The east Asian raccoon dog (''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 a Basal (phylogenetics), basal species of Canidae, canid. Fossil records indicate this canid ...

(''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

, 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, at times called matriliny, is the tracing of kinship through the female line. It may also correlate with a social system in which people identify with their matriline, their mother's lineage, and which can involve the inheritan ...

founders.

Distribution and habitat

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

from southern

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

(

Manitoba Manitoba is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population ...

through southeastern

Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...

) 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 considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

(

Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

and

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

), excluding the mountains of northwestern United States. The species prefers a mix of wooded and agricultural land in the Midwest, juniper forests as well as ponderosa pine in the west, and deciduous forests in the east. 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. The species prefers a mix of forest and agricultural land towards the southern part of their range (Belize ). In southeastern Mexico, the species prefers areas with a human presence such as near roads.

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 gray wolf. Also called the domestic dog, it was selectively bred from a population of wolves during the Late Pleistocene by hunter-gatherers ...

or the

coyote The coyote (''Canis latrans''), also known as the American jackal, prairie wolf, or brush wolf, is a species of canis, canine native to North America. It is smaller than its close relative, the Wolf, gray wolf, and slightly smaller than the c ...

, or to reach tree-bound or arboreal food sources. It can climb branchless, vertical trunks to heights of 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''), also referred to as the domestic cat or house cat, is a small Domestication, domesticated carnivorous mammal. It is the only domesticated species of the family Felidae. Advances in archaeology and genetics have sh ...

. The gray fox is primarily

nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...

crepuscular In zoology, a crepuscular animal is one that is active primarily during the twilight period, being matutinal (active during dawn), vespertine (biology), vespertine/vespertinal (active during dusk), or both. This is distinguished from diurnalit ...

and makes its den in hollow trees, stumps or appropriated burrows during the day. Such gray fox tree dens may be located 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 choose habitats that will allow escape from coyotes, therefore the foxes's tendency to live 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. 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 Interspecific competition, in ecology, is a form of competition in which individuals of ''different'' species compete for the same resources in an ecosystem (e.g. food or living space). This can be contrasted with mutualism, a type of symbiosis. ...

, 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 may also avoid competitors by occupying different

habitat In ecology, habitat refers to the array of resources, 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 manifestation of its ...

s from them. In

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

, gray foxes do this by living in

chaparral Chaparral ( ) is a shrubland plant plant community, community found primarily in California, southern Oregon, and northern Baja California. It is shaped by a Mediterranean climate (mild wet winters and hot dry summers) and infrequent, high-intens ...

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 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

mesopredator A mesopredator is a predator that occupies a mid-ranking trophic level in a food web. There is no standard definition of a mesopredator, but mesopredators are usually medium-sized carnivorous or omnivorous animals, such as raccoons, foxes, or ...

s 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 or superpredator, 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 hig ...

s due to the removal of other apex predators, like

wolves The wolf (''Canis lupus''; : wolves), also known as the grey wolf or gray wolf, is a canine native to Eurasia and North America. More than thirty subspecies of ''Canis lupus'' have been recognized, including the dog and dingo, though gr ...

, 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 relationship of two individuals in which they form a mutual and exclusive intimate partnership. Having only one partner at any one time, whether for life or serial monogamy, contrasts with various forms of non-monogamy (e.g. ...

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

Michigan Michigan ( ) is a peninsular U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, Upper Midwestern United States. It shares water and land boundaries with Minnesota to the northwest, Wisconsin to the west, ...

, the gray fox mates in early March, in

Alabama Alabama ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South, Deep Southern regions of the United States. It borders Tennessee to the north, Georgia (U.S. state), Georgia to the east, Florida and the Gu ...

, 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, moving up to . The juvenile females stayed within proximity of the den within and always returned. Adult gray foxes showed no signs of dispersion for either sex. The gray fox will typically live between six and ten years. The annual reproductive cycle of males has been described through epididymal smears. They become fertile earlier and remain fertile longer than 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

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 shrub ...

(''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 dif ...

s, and

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

s. In California, the gray fox primarily eats rodents (such as

deer mice ''Peromyscus'' is a genus of rodents. They are commonly referred to as deer mice or deermice, not to be confused with the chevrotain or "mouse deer". They are New World mice only distantly related to the common house and laboratory mouse, ''M ...

, woodrats, and cotton rats), followed by

lagomorph The lagomorphs () are the members of the taxonomic order Lagomorpha, of which there are two living families: the Leporidae (rabbits and hares) and the Ochotonidae ( pikas). There are 110 recent species of lagomorph, of which 109 species in t ...

s, e.g. jackrabbit, brush rabbit, etc. When it is available, gray foxes may also feed on

carrion Carrion (), also known as a carcass, is the decaying flesh of dead animals. 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 (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...

s are readily available, generally eating more vegetable matter than does the

(''Vulpes vulpes''). Generally, there is an increase in fruits and invertebrates (such as

grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are amongst what are possibly the most ancient living groups of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grassh ...

beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...

butterflies Butterflies are winged insects from the lepidopteran superfamily Papilionoidea, characterized by large, often brightly coloured wings that often fold together when at rest, and a conspicuous, fluttering flight. The oldest butterfly fossi ...

, and

moth Moths are a group of insects that includes all members of the order Lepidoptera that are not Butterfly, butterflies. They were previously classified as suborder Heterocera, but the group is Paraphyly, paraphyletic with respect to butterflies (s ...

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. 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 ''Metorchis conjunctus'', common name Canadian liver fluke, is a species of trematode parasite in the family Opisthorchiidae. It can infect mammals that eat raw fish in North America. The first intermediate host is a freshwater snail and the seco ...

''. Other common parasites that were collected on gray foxes in Texas were a variety of tapeworms ('' Mesocestoides litteratus'', '' Taenia pisiformis'', '' Taenia serialis'') and roundworms ('' Ancylostoma caninum'', ''

Ancylostoma braziliense ''Ancylostoma braziliense'' is a species of hookworm belonging to the genus ''Ancylostoma''. It is an intestinal parasite of domestic cats and dogs. Severe infection is often fatal to these pets, especially in puppies and kittens. The infection i ...

'', '' Haemonchus similis'', '' Spirocerca lupi'', '' Physaloptera rara'', '' Eucoleus aerophilus''). ''T. pisiformis'' was the most common parasite species and was associated with frequent impacts on health.

References

External links

* * * {{Authority control Carnivorans of North America South American foxes

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 Taxa named by Johann Christian Daniel von Schreber