Fox

Foxes are generally smaller than some other members of the family Canidae such as wolves and jackals, while they may be larger than some within the family, such as Raccoon dogs. In the largest species, the red fox, males weigh on average between 4.1 and 8.7 kilograms (9 and 19+1⁄4 pounds),[7] while the smallest species, the fennec fox, weighs just 0.7 to 1.6 kg (1+1⁄2 to 3+1⁄2 lb).[8]

Fox features typically include a triangular face, pointed ears, an elongated rostrum, and a bushy tail. They are digitigrade (meaning they walk on their toes). Unlike most members of the family Canidae, foxes have partially retractable claws.[9] Fox vibrissae, or whiskers, are black. The whiskers on the muzzle, known as mystacial vibrissae, average 100–110 millimetres (3+7⁄8–4+3⁄8 inches) long, while the whiskers everywhere else on the head average to be shorter in length. Whiskers (carpal vibrissae) are also on the forelimbs and average 40 mm (1+5⁄8 in) long, pointing downward and backward.[2] Other physical characteristics vary according to habitat and adaptive significance.

Fox species differ in fur color, length, and density. Coat colors range from pearly white to black-and-white to black flecked with white or grey on the underside. Fennec foxes (and other species of fox adapted to life in the desert, such as kit foxes), for example, have large ears and short fur to aid in keeping the body cool.[2][9] Arctic foxes, on the other hand, have tiny ears and short limbs as well as thick, insulating fur, which aid in keeping the body warm.[10] Red foxes, by contrast, have a typical auburn pelt, the tail normally ending with a white marking.[11]

A fox's coat color and texture may vary due to the change in seasons; fox pelts are richer and denser in the colder months and lighter in the warmer months. To get rid of the dense winter coat, foxes moult once a year around April; the process begins from the feet, up the legs, and then along the back.[9] Coat color may also change as the individual ages.[2]

A fox's dentition, like all other canids, is I 3/3, C 1/1, PM 4/4, M 3/2 = 42. (Bat-eared foxes have six extra molars, totalling in 48 teeth.) Foxes have pronounced carnassial pairs, which is characteristic of a carnivore. These pairs consist of the upper premolar and the lower first molar, and work together to shear tough material like flesh. Foxes' canines are pronounced, also characteristic of a carnivore, and are excellent in gripping prey.[12]

Arctic fox curled up in snow

In the wild, the typical lifespan of a fox is one to three years, although individuals may live up to ten years. Unlike many canids, foxes are not always pack animals. Typically, they live in small family groups, but some (such as Arctic foxes) are known to be solitary.[2][9]

Foxes are omnivores.[13][14] Their diet is made up primarily of invertebrates such as insects and small vertebrates such as reptiles and birds. They may also eat eggs and vegetation. Many species are generalist predators, but some (such as the crab-eating fox) have more specialized diets. Most species of fox consume around 1 kg (2.2 lb) of food every day. Foxes cache excess food, burying it for later consumption, usually under leaves, snow, or soil.[9][15] While hunting, foxes tend to use a particular pouncing technique, such that they crouch down to camouflage themselves in the terrain and then use their hind legs to leap up with great force and land on top of their chosen prey.[2] Using their pronounced canine teeth, they can then grip the prey's neck and shake it until it is dead or can be readily disemboweled.[2]

The gray fox is one of only two canine species known to regularly climb trees; the other is the raccoon dog.[16]

The male fox's scrotum is held up close to the body with the testes inside even after they descend. Like other canines, the male fox has a baculum, or penile bone.[2][17][18] The testes of red foxes are smaller than those of Arctic foxes.[19] Sperm formation in red foxes begins in August–September, with the testicles attaining their greatest weight in December–February.[20]

Vixens are in heat for one to six days, making their reproductive cycle twelve months long. As with other canines, the ova are shed during estrus without the need for the stimulation of copulating. Once the egg is fertilized, the vixen enters a period of gestation that can last from 52 to 53 days. Foxes tend to have an average litter size of four to five with an 80 percent success rate in becoming pregnant.[2][21] Litter sizes can vary greatly according to species and environment – the Arctic fox, for example, can have up to eleven kits.[22]

The vixen usually has six or eight mammae.[23] Each teat has 8 to 20 lactiferous ducts, which connect the mammary gland to the nipple, allowing for milk to be carried to the nipple.

The fox's vocal repertoire is vast, and includes:

Whine

Made shortly after birth. Occurs at a high rate when kits are hungry and when their body temperatures are low. Whining stimulates the mother to care for her young; it also has been known to stimulate the male fox into caring for his mate and kits.

Yelp

Made about 19 days later. The kits' whining turns into infantile barks, yelps, which occur heavily during play.

Explosive call

At the age of about one month, the kits can emit an explosive call which is intended to be threatening to intruders or other cubs; a high-pitched howl.

Combative call

In adults, the explosive call becomes an open-mouthed combative call during any conflict; a sharper bark.

Growl

An adult fox's indication to their kits to feed or head to the adult's location.

Bark

Adult foxes warn against intruders and in defense by barking.[2][24]

In the case of domesticated foxes, the whining seems to remain in adult individuals as a sign of excitement and submission in the presence of their owners.[2]

The island fox, though considered a near-threatened species throughout the world, is becoming increasingly endangered in its endemic environment of the California Channel Islands.[28] A population on an island is smaller than those on the mainland because of limited resources like space, food and shelter.[29] Island populations are therefore highly susceptible to external threats ranging from introduced predatory species and humans to extreme weather.[29]

On the California Channel Islands, it was found that the population of the island fox was so low due to an outbreak of canine distemper virus from 1999 to 2000[30] as well as predation by non-native golden eagles.[31] Since 1993, the eagles have caused the population to decline by as much as 95%.[30] Because of the low number of foxes, the population went through an Allee effect (an effect in which, at low enough densities, an individual's fitness decreases).[28] Conservationists had to take healthy breeding pairs out of the wild population to breed them in captivity until they had enough foxes to release back into the wild.[30] Nonnative grazers were also removed so that native plants would be able to grow back to their natural height, thereby providing adequate cover and protection for the foxes against golden eagles.[31]

Darwin's fox is considered critically endangered because of their small known population of 250 mature individuals as well as their restricted distribution.[32] On the Chilean mainland, the population is limited to Nahuelbuta National Park and the surrounding Valdivian rainforest.[32] Similarly on Chiloé Island, their population is limited to the forests that extend from the southernmost to the northwesternmost part of the island.[32] Though the Nahuelbuta National Park is protected, 90% of the species live on Chiloé Island.[33]

A major issue the species faces is their dwindling, limited habitat due to the cutting and burning of the unprotected forests.[32] Because of deforestation, the Darwin's fox habitat is shrinking, allowing for their competitor's (chilla fox) preferred habitat of open space, to increase; the Darwin's fox, subsequently, is being outcompeted.[34] Another problem they face is their inability to fight off diseases transmitted by the increasing number of pet dogs.[32] To conserve these animals, researchers suggest the need for the forests that link the Nahuelbuta National Park to the coast of Chile and in turn Chiloé Island and its forests, to be protected.[34] They also suggest that other forests around Chile be examined to determine whether Darwin's foxes have previously existed there or can live there in the future, should the need to reintroduce the species to those areas arise.[34] And finally, the researchers advise for the creation of a captive breeding program, in Chile, because of the limited number of mature individuals in the wild.[34]

Fox hunting originated in the United Kingdom in the 16th century. Hunting with dogs is now banned in the United Kingdom,[41][42][43][44] though hunting without dogs is still permitted. Red foxes were introduced into Australia in the early 19th century for sport, and have since become widespread through much of the country. They have caused population decline among many native species and prey on livestock, especially new lambs.[45] Fox hunting is practiced as recreation in several other countries including Canada, France, Ireland, Italy, Russia, United States and Australia.

A tame fox in Talysarn, Wales

There are many records of domesticated red foxes and others, but rarely of sustained domestication. A recent and notable exception is the Russian silver fox,[46] which resulted in visible and behavioral changes, and is a case study of an animal population modeling according to human domestication needs. The current group of domesticated silver foxes are the result of nearly fifty years of experiments in the Soviet Union and Russia to domesticate the silver morph of the red fox. This selective breeding resulted in physical and behavioral traits appearing that are frequently seen in domestic cats, dogs, and other animals, such as pigmentation changes, floppy ears, and curly tails.[47] Notably, the new foxes became more tame, allowing themselves to be petted, whimpering to get attention and sniffing and licking their caretakers.[48]

In the United Kingdom, a number of cases of non-fatal attacks on humans have been reported. They often involved children, or if there were gaps in homes through which foxes could pass.[49]

Foxes are among the comparatively few mammals which have been able to adapt themselves to a certain degree to living in urban (mostly suburban) human environments. Their omnivorous diet allows them to survive on discarded food waste, and their skittish and often nocturnal nature means that they are often able to avoid detection, despite their larger size.

Urban foxes have been identified as threats to cats and small dogs, and for this reason there is often pressure to exclude them from these environments.[50]

The San Joaquin kit fox is a highly endangered species that has, ironically, become adapted to urban living in the San Joaquin Valley and Salinas Valley of southern California. Its diet includes mice, ground squirrels, rabbits, hares, bird eggs, and insects, and it has claimed habitats in open areas, golf courses, drainage basins, and school grounds.[50]

Plate in the shape of two peaches depicting two foxes, Tang dynasty

The fox appears in many cultures, usually in folklore. However, there are slight variations in their depictions. In Western and Persian folklore, foxes are symbols of cunning and trickery—a reputation derived especially from their reputed ability to evade hunters. This is usually represented as a character possessing these traits. These traits are used on a wide variety of characters, either making them a nuisance to the story, a misunderstood hero, or a devious villain.

In Asian folklore, foxes are depicted as familiar spirits possessing magic powers. Similar to in Western folklore, foxes are portrayed as mischievous, usually tricking other people, with the ability to disguise as an attractive female human. However, there are other depictions of foxes as mystical, sacred creatures that can either bring wonder or ruin.[51] Nine-tailed foxes appear in Chinese folklore, literature, and mythology, in which, depending on the tale, they can be a good or a bad omen.[52] The motif was eventually introduced from Chinese to Japanese and Korean cultures.[53]

The constellation Vulpecula represents a fox.[54]