Gray fox

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Gray fox
Grey Fox (Urocyon cinereoargenteus).jpg
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Canidae
Genus: Urocyon
Species:
U. cinereoargenteus
Binomial name
Urocyon cinereoargenteus
(Schreber, 1775)
Leefgebied grijze vos.JPG
Gray fox range

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, the diminutive Channel Island fox (Urocyon littoralis), are the only living members of the genus Urocyon , which is considered to be the most basal of the living canids. Though it was once the most common fox in the eastern United States, and still is found there, human advancement and deforestation allowed the red fox to become more dominant. The Pacific States still have the gray fox as a dominant. It is the only American canid that can climb trees. Its specific epithet cinereoargenteus means "ashen silver".

Mammal class of tetrapods

Mammals are vertebrate animals constituting the class Mammalia, and characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex, fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles and birds, from which they diverged in the late Triassic, 201–227 million years ago. There are around 5,450 species of mammals. The largest orders are the rodents, bats and Soricomorpha. The next three are the Primates, the Cetartiodactyla, and the Carnivora.

Canidae family of mammals

The biological family Canidae is a lineage of carnivorans that includes domestic dogs, wolves, coyotes, foxes, jackals, dingoes, and many other extant and extinct dog-like mammals. A member of this family is called a canid.

North America Continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere

North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere. It is also considered by some to be a northern subcontinent of the Americas. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, and to the southeast by South America and the Caribbean Sea.

Contents

Description

The gray fox is mainly distinguished from most other canids by its grizzled upper parts, black stripe down its tail and strong neck, 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 (29.9 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 15.4 lb), though exceptionally can weigh as much as 9 kg (20 lb). [2] [3] [4] It is readily differentiated from the red fox by the lack of "black stockings" that stand out on the latter and the stripe of black hair that runs along the middle of the tail as well as individual guard hairs being banded with white, gray, and black. [5] The gray fox displays white on the ears, throat, chest, belly and hind legs. [5] In contrast to all Vulpes and related (Arctic and fennec) foxes, the gray fox has oval (instead of slit-like) pupils. [6]

Red fox species of mammal

The red fox 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 from the Arctic Circle to North Africa, North America and Eurasia. It is listed as least concern by the IUCN. Its range has increased alongside human expansion, having been introduced to Australia, where it is considered harmful to native mammals and bird populations. Due to its presence in Australia, it is included on the list of the "world's 100 worst invasive species".

<i>Vulpes</i> genus of mammals in the family Canidae

Vulpes is a genus of the Canidae. The members of this genus are colloquially referred to as true foxes, meaning they form a proper clade. The word "fox" occurs on the common names of species. True foxes are distinguished from members of the genus Canis, such as dogs, wolves, coyotes, and jackals, by their smaller size (5–11 kg) and flatter skull. They have black, triangular markings between their eyes and nose, and the tip of their tail is often a different color from the rest of their pelt. The typical lifespan for this genus is between two and four years, but can reach up to a decade.

The dental formula of the U. cinereoargenteus is 3.1.4.23.1.4.3 = 42. [5]

Origin and genetics

Gray fox kit at the Palo Alto Baylands in California Gray fox kit at the Baylands Bill Leikam 12-14-2011.jpg
Gray fox kit at the Palo Alto Baylands in California

The gray fox appeared in North America during the mid-Pliocene (Hemphillian land animal age) 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 like the giant sloth, the elephant-like Cuvieronius , the 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 spp.). 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] 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. [9] Faunal remains at two northern California cave sites confirm the presence of the gray fox during the late Pleistocene. [10] 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. [11] Recent mitochondrial genetic studies suggests divergence of North American eastern and western gray foxes in the Irvingtonian mid-Pleistocene into separate sister taxa. [12]

The Pliocene Epoch is the epoch in the geologic timescale that extends from 5.333 million to 2.58 million years BP. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch. Prior to the 2009 revision of the geologic time scale, which placed the four most recent major glaciations entirely within the Pleistocene, the Pliocene also included the Gelasian stage, which lasted from 2.588 to 1.806 million years ago, and is now included in the Pleistocene.

Graham County, Arizona County in the United States

Graham County is a county located in the southeastern part of the U.S. state of Arizona. As of the 2010 census, the population was 37,220, making it the third-least populous county in Arizona. The county seat is Safford.

<i>Megalonyx</i> Extinct genus of ground sloth

Megalonyx is an extinct genus of ground sloths of the family Megalonychidae, which was endemic to North America from the Hemphillian of the Late Miocene through to the Rancholabrean of the Pleistocene, living from ~10.3 Mya—11,000 years ago, existing for approximately 10.289 million years. The type species, M. jeffersonii, measured about 3 meters (9.8 ft) and weighed up to 1,000 kilograms (2,200 lb).

The gray fox's dwarf relative, the Channel Island fox, is likely descended from mainland gray foxes. [13] 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 founders. [12] The genus Urocyon is considered to be the most basal of the living canids. [14]

A genus is a taxonomic rank used in the biological classification of living and fossil organisms, as well as viruses, in biology. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.

<i>Urocyon</i> genus of mammals

The genus Urocyon is a genus that contains two living Western Hemisphere foxes in the family Canidae; the gray fox and the closely related island fox, which is a dwarf cousin of the gray fox; as well as one fossil species, Urocyon progressus.

In phylogenetics, basal is the direction of the base of a rooted phylogenetic tree or cladogram. The term may be more strictly applied only to nodes adjacent to the root, or more loosely applied to nodes regarded as being close to the root. Each node in the tree corresponds to a clade; i.e., clade C may be described as basal within a larger clade D if its root is directly linked to the root of D. The terms deep-branching or early-branching are similar in meaning.

Distribution and habitat

The species occurs throughout most rocky, wooded, brushy regions of the southern half of North America from southern Canada (Manitoba through southeastern Quebec) [15] to the northern part of South America (Venezuela and Colombia), excluding the mountains of northwestern United States. [16] It is the only canid whose natural range spans both North and South America. [17] In some areas, high population densities exist near brush-covered bluffs. [5]

Canada Country in North America

Canada is a country in the northern part of North America. Its ten provinces and three territories extend from the Atlantic to the Pacific and northward into the Arctic Ocean, covering 9.98 million square kilometres, making it the world's second-largest country by total area. Canada's southern border with the United States, stretching some 8,891 kilometres (5,525 mi), is the world's longest bi-national land border. Its capital is Ottawa, and its three largest metropolitan areas are Toronto, Montreal, and Vancouver. As a whole, Canada is sparsely populated, the majority of its land area being dominated by forest and tundra. Consequently, its population is highly urbanized, with over 80 percent of its inhabitants concentrated in large and medium-sized cities, with 70% of citizens residing within 100 kilometres (62 mi) of the southern border. Canada's climate varies widely across its vast area, ranging from arctic weather in the north, to hot summers in the southern regions, with four distinct seasons.

Manitoba Province of Canada

Manitoba is a province at the longitudinal centre of Canada. It is often considered one of the three prairie provinces and is Canada's fifth-most populous province with its estimated 1.3 million people. Manitoba covers 649,950 square kilometres (250,900 sq mi) with a widely varied landscape, stretching from the northern oceanic coastline to the southern border with the United States. The province is bordered by the provinces of Ontario to the east and Saskatchewan to the west, the territories of Nunavut to the north, and Northwest Territories to the northwest, and the U.S. states of North Dakota and Minnesota to the south.

Quebec Province of Canada

Quebec is one of the thirteen provinces and territories of Canada. It is bordered to the west by the province of Ontario and the bodies of water James Bay and Hudson Bay; to the north by Hudson Strait and Ungava Bay; to the east by the Gulf of Saint Lawrence and the province of Newfoundland and Labrador; and to the south by the province of New Brunswick and the U.S. states of Maine, New Hampshire, Vermont, and New York. It also shares maritime borders with Nunavut, Prince Edward Island, and Nova Scotia. Quebec is Canada's largest province by area and its second-largest administrative division; only the territory of Nunavut is larger. It is historically and politically considered to be part of Central Canada.

Behavior

A yawning gray fox, northern Florida GrayFoxApr04NFla.jpg
A yawning gray fox, northern Florida

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, [18] 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. [19] It descends primarily by jumping from branch to branch, or by descending slowly backwards as a domestic cat would do. The gray fox is primarily nocturnal or crepuscular 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. [6] 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 since they are the more adaptable species to development and urbanization. [20] In areas where both red and gray foxes exist, the gray fox is dominant. [21]

Reproduction

Gray fox, showing black tail stripe, Sierra Nevada Urocyon cinereoargenteus grayFox cameo.jpg
Gray fox, showing black tail stripe, Sierra Nevada

The gray fox is assumed 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. The gestation period lasts approximately 53 days. Litter size ranges from 1 to 7, with a mean of 3.8 young per female. 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 four 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. [9] Out of a study of nine juvenile gray foxes, only the males dispersed up to 84 km. The juvenile females stayed within proximity of the den within 3 km and always returned. [22] On the other hand, adult gray foxes showed no signs of dispersion for either gender. [23]

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. [9]

Dens are used at any time during the year but mostly during whelping season. Dens are built in brushy or wooded regions and are less obvious than the dens of the red fox. Logs, trees, rocks, burrows, or abandoned dwellings serve as suitable den sites. [5]

Diet

Greyfox.jpg
A gray fox at night
Adult Male & Female Grey Fox.jpg
Adult male and female gray fox

The gray fox is an omnivorous, solitary hunter. It frequently preys on 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. [18] 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. [21] 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). [2]

Subspecies

Gray fox skull Virginianusskull.jpg
Gray fox skull

There are 16 subspecies recognized for the gray fox. [9]

Parasites

Parasites of gray fox include trematode Metorchis conjunctus . [24]

See also

Related Research Articles

Arctic fox species of mammal

The Arctic fox, also known as the white fox, polar fox, or snow fox, is a small fox native to the Arctic regions of the Northern Hemisphere and common throughout the Arctic tundra biome. It is well adapted to living in cold environments, and is best known for its thick, warm fur that is also used as camouflage. On average, Arctic foxes only live 3–4 years in the wild. Its body length ranges from 46 to 68 cm, with a generally rounded body shape to minimize the escape of body heat.

Fennec fox small crepuscular animals

The fennec fox, or fennec, is a small crepuscular fox found in the Sahara of North Africa, the Sinai Peninsula, South West Israel and the Arabian desert. Its most distinctive feature is its unusually large ears, which also serve to dissipate heat. Its name comes from the Berber-Arabic word (fanak), which means fox. The fennec is the smallest species of canid. Its coat, ears, and kidney functions have adapted to high-temperature, low-water, desert environments. Also, its hearing is sensitive enough to hear prey moving underground. It mainly eats insects, small mammals, and birds.

Maned wolf species of mammal

The maned wolf is the largest canid of South America. Its markings resemble those of foxes, but it is neither a fox nor a wolf. It is the only species in the genus Chrysocyon.

<i>Canis</i> genus of mammals

Canis is a genus of the Canidae containing multiple extant species, such as wolves, coyotes, jackals, dingoes, and dogs. Species of this genus are distinguished by their moderate to large size, their massive, well-developed skulls and dentition, long legs, and comparatively short ears and tails.

Kit fox species of mammal

The kit fox is a fox species of North America. Its range is primarily in the Southwestern United States and northern and central Mexico. Some mammalogists classify it as conspecific with the swift fox, V. velox, but molecular systematics imply that the two species are distinct.

Swift fox species of mammal

The swift fox is a small light orange-tan fox around the size of a domestic cat found in the western grasslands of North America, such as Montana, Colorado, New Mexico, Kansas, Oklahoma and Texas. It also lives in Manitoba, Saskatchewan and Alberta in Canada, where it was previously extirpated. It is closely related to the kit fox and the two species are sometimes known as subspecies of Vulpes velox because hybrids of the two species occur naturally where their ranges overlap.

Bengal fox species of mammal

The Bengal fox, also known as the Indian fox, is a fox endemic to the Indian subcontinent and is found from the Himalayan foothills and Terai of Nepal through southern India and from southern and eastern Pakistan to eastern India and southeastern Bangladesh.

The North American red fox is the largest of the true foxes and one of the most widely distributed members of the order Carnivora, occurring in North America. It is listed as least concern by the IUCN.

Caninae subfamily of carnivorans

In the history of the carnivores, the family Canidae is represented by the two extinct subfamilies designated as Hesperocyoninae and Borophaginae, and the extant subfamily Caninae. This subfamily includes all living canids and their most recent fossil relatives. Their fossils have been found in Lower Oligocene North America, and they did not spread to Asia until the end of the Miocene, some 7 million to 8 million years ago. Many extinct species of Caninae were endemic to North America, living from 34 million to 11,000 years ago.

Sierra Nevada red fox subspecies of mammal

The Sierra Nevada red fox, also known as the High Sierra fox, is a subspecies of red fox and likely one of the most endangered mammals in North America. The fox's Sierra Nevada Distinct Population Segment is estimated at 29 adults near Sonora Pass in California. The Southern Cascades Distinct Population Segment consists of an estimated 42 adults near Lassen Volcanic National Park and an unknown number of individuals in five areas of Oregon. No other populations are known. Interbreeding with non-native red foxes and recruitment success are primary conservation concerns.

Urocyon progressus is an extinct canid of the genus Urocyon, and lived in North America during the Blancan Stage on the geologic timescale. Fossil samples have been found in both Kansas and Texas. It may have been the ancestor of the modern gray fox.

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References

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Bibliography