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.
Twelve species belong to the monophyletic "true fox" group of genus Vulpes. Another 25 current or extinct species are sometimes called foxes – they are part of the paraphyletic group of the South American foxes or an outlying group, which consists of the bat-eared fox, gray fox, and island fox.
Foxes live on every continent except Antarctica. The most common and widespread species of fox is the red fox with about 47 recognized subspecies. The global distribution of foxes, together with their widespread reputation for cunning, has contributed to their prominence in popular culture and folklore in many societies around the world. The hunting of foxes with packs of hounds, long an established pursuit in Europe, especially in the British Isles, was exported by European settlers to various parts of the New World.
Etymology
The word fox comes from Old English and derives from Proto-Germanic *fuhsaz. This in turn derives from Proto-Indo-European *puḱ- "thick-haired, tail." Male foxes are known as dogs, tods, or reynards; females as vixens; and young as cubs, pups, or kits, though the last term is not to be confused with the kit fox, a distinct species. "Vixen" is one of very few modern English words that retain the Middle English southern dialectal "v" pronunciation instead of "f"; i.e., northern English "fox" versus southern English "vox". A group of foxes may be referred to as a skulk, leash, or earth.Phylogenetic relationships
Within the Canidae, the results of DNA analysis shows several phylogenetic divisions:- The fox-like canids, which include the kit fox, red fox, Cape fox, Arctic fox, fennec fox, and bat-eared fox .
- The wolf-like canids, including the dog , gray wolf, red wolf, eastern wolf, coyote, golden jackal, Ethiopian wolf, black-backed jackal, side-striped jackal, dhole, and African wild dog.
- The South American canids, including the bush dog, hoary fox, crab-eating fox and maned wolf.
- Various monotypic taxa, including the gray fox.
Biology
General morphology
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 between, while the smallest species, the fennec fox, weighs.Fox features typically include a triangular face, pointed ears, an elongated rostrum, and a bushy tail. They are digitigrade. Unlike most members of the family Canidae, foxes have partially retractable claws. Fox vibrissae, or whiskers, are black. The whiskers on the muzzle, known as mystacial vibrissae, average long, while the whiskers everywhere else on the head average to be shorter in length. Whiskers are also on the forelimbs and average long, pointing downward and backward. Other physical characteristics vary according to habitat and adaptive significance.
Pelage
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, for example, have large ears and short fur to aid in keeping the body cool. 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. Red foxes, by contrast, have a typical auburn pelt, the tail normally ending with a white marking.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. Coat color may also change as the individual ages.
Dentition
A fox's dentition, like all other canids, is I 3/3, C 1/1, PM 4/4, M 3/2 = 42. 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.Behaviour
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 are known to be solitary.Foxes are omnivores. 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 have more specialized diets. Most species of fox consume around of food every day. Foxes cache excess food, burying it for later consumption, usually under leaves, snow, or soil. 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. 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.
The gray fox is one of only two canine species known to regularly climb trees; the other is the raccoon dog.
Sexual characteristics
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. The testes of red foxes are smaller than those of Arctic foxes. Sperm formation in red foxes begins in August–September, with the testicles attaining their greatest weight in December–February.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. Litter sizes can vary greatly according to species and environmentthe Arctic fox, for example, can have up to eleven kits.
The vixen usually has six or eight mammae. 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.
Vocalization
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.
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.
Classification
Canids commonly known as foxes include the following genera and species:| Genus | Species | Picture |
| Canis | Ethiopian wolf, sometimes called the Simien fox or Simien jackal | |
| Cerdocyon | Crab-eating fox | |
| † Dusicyon | Extinct genus, including the Falkland Islands wolf, sometimes known as the Falklands Islands fox | File:FalklandIslandFox2.jpg|thumb| Falkland Islands wolf Illustration by John Gerrard Keulemans |
| Lycalopex |
| |
| Otocyon | Bat-eared fox | File:Bat eared fox Kenya crop.jpg|thumb|Bat-eared fox in Kenya |
| Urocyon | ||
| Vulpes |
Conservation
Several fox species are endangered in their native environments. Pressures placed on foxes include habitat loss and being hunted for pelts, other trade, or control. Due in part to their opportunistic hunting style and industriousness, foxes are commonly resented as nuisance animals. Contrastingly, foxes, while often considered pests themselves, have been successfully employed to control pests on fruit farms while leaving the fruit intact.''Urocyon littoralis''
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. In general, a population on an island will be smaller than one on a mainland because of limited resources like space, food and shelter. Island populations are therefore highly susceptible to external threats ranging from introduced predatory species and humans to extreme weather.On the California Channel Islands, it was found that the population of the island fox was low due to an outbreak of canine distemper virus from 1999 to 2000 as well as predation by non-native golden eagles. Since 1993, the eagles have caused the population to decline by as much as 95%. Because of the low number of foxes, the population went through an Allee effect. 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. 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.