Vulpes

Diversity

the genus Vulpes is made up of 12 extant species, all referred to as the “true foxes.” There are 6 species only known from fossils. Foxes are part of the Family Canidae which also includes wolves, coyotes, and dogs, but we are able to see some distinct characteristics separating foxes into their own genus. Foxes are distinguished by their small size, flattened skulls with pointed snouts, and a large bushy tail (California Academy of Science, 2018). “Vulpes” means fox in Latin. The best known and most widely distributed species, Vulpes vulpes , was first described by Linnaeus in 1758. Due to the vast land area the red fox occupies, it has been suggested that there may be more genetically distinct species within the genus yet to be described (Hoffman and Sillero-Zubiri, 2016).

Geographic Range

Red foxes are found throughout much of the northern hemisphere, from North America, Europe, and India to Japan. Several introductions of red foxes have resulted in non-native ranges in Australia, Tasmania, and New Zealand (Hoffman and Sillero-Zubiri, 2016). Some fox species have smaller ranges with more extreme climates such as in the northern tundra and arctic regions. Foxes are not found in tropical regions. The majority of the diversity is found in northern latitudes (Hoffman and Sillero-Zubiri, 2016).

• Biogeographic Regions
• nearctic nearctic
  • native native
• palearctic palearctic
  • native native
• ethiopian ethiopian
  • native native
• australian australian
  • introduced introduced

Habitat

Foxes are found in a wide range of habitats from the desert (fennec fox, Vulpes zerda ) to the Arctic (arctic fox, Vulpes lagopus ), and from high elevations in the mountains to open plains (Hoffman and Sillero-Zubiri, 2016). Foxes are opportunistic and thrive where they are able to find food and shelter. Foxes are common in suburban and urban areas where they can take advantage of human food sources, but tend to stay clear of large industrial areas (Dorning and Harris, 2017). In many regions foxes tend to thrive where humans are also found, appearing in many agricultural areas, farmland, and in patchy woodland (Hoffman and Sillero-Zubiri, 2016).

• Habitat Regions
• temperate temperate
• polar polar
• terrestrial terrestrial

• Terrestrial Biomes
• tundra tundra
• desert or dune desert or dune
• savanna or grassland savanna or grassland
• forest forest
• scrub forest scrub forest
• mountains mountains
• icecap

• Other Habitat Features
• urban urban
• suburban suburban
• agricultural agricultural

Systematic and Taxonomic History

Taxonomists currently believe that the carnivores evolved from an animal called a miacid Miacidae , which was a small tree-living mammal. During the mid-Eocene carnivores split into two suborders that we know today as Caniformia , the dogs, and Feliformia , the cats. Caniforms diverged into three lineages or subfamilies: the Hesperocyoninae (western dogs), the Borophaginae (bone-crushing dogs), and the only extant group, the Canidae which includes dogs, wolves, coyotes, foxes, etc. The canid group branched out on its own around 10 mya, most likely as a result of an open niche from past groups of canines dying out. Ultimately this was the rise of the three modern day groups which can be further broken down: Canini (dogs, wolves, etc), Urocyon (grey fox and island fox), and Vulpini . This period marked the divergence of true foxes from the wolf-dog lineage (Baldwin, 2015).

Vulpes is made up of 12 species, but there are about 27 extant species of foxes spread over 9 different genera (New World Encyclopedia, 2017). Discovery of Vulpes was originally credited to the German zoologist Just Leopold Frisch who, in 1775, published a thesis on the taxonomy of four-footed animals where he described Vulpes vulgaris and Vulpes crucifer , both referring to the "common" fox. After Frisch, many scientists used Vulpes to refer to the red fox, but in 1954 the International Commission on Zoological Nomenclature (ICZN) rejected Frisch's original thesis. In 1979 the ICZN changed their ruling after several mammalogists argued that changing Vulpes to Canis would become to confusing after using it for such a long period of time. It was also later discovered that a French naturalist, Francois Alexandre Pierre de Garsault, had published work in 1764 before Frisch that used Vulpes to describe what was a red fox Vulpes vulpes (Baldwin, 2015). The 1800s consisted of several names being used to describe this group, with many of them still today relating to certain species (Wilson & Reeder, 2018).

Physical Description

Foxes have a dog-like appearance, but on average are quite a bit smaller in size compared to most other canids. They have shorter legs with a slender body, a distinct flattened skull with a pointed snout known as a “fox face” and varying sizes of upright pointed ears. Like all canids, foxes have a muscular frame, strong jaws, and teeth for grasping prey. Blunt claws are primarily useful for gripping the ground when chasing down their meal. Contributing to the foxes’ lengthy appearance is its long bushy tail that makes up about one third of its body length and in many species consists of a black tip or small accent at the end. The tail can also be used for the purpose of keeping warm by wrapping it around their bodies (National Geographic, 2018). Usually ranging in size from 92-107 cm in length and weighing around 4.5-5 kg, generally the males being larger (Saunders, 1988). Several traits vary to some extent depending on which species you are looking at and how they have adapted to survive in their habitat. For example, the arctic fox ( Vulpes lagopus ) has a very dense, insulated coat to block out the harsh cold temperatures and small ears to prevent heat loss. On the other hand a species such as the fennec fox ( Vulpes zerda ) that lives in the desert has a very thin coat and large ears to help stay cool. A solid color coat is found in the majority of species, but there are instances where the coat color changes throughout the year to better camouflage against the current seasons landscape (New World Encyclopedia, 2017).

• Other Physical Features
• endothermic endothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Reproduction

Foxes are solitary animals that spend most of their time alone. Many foxes are monogamous, meaning a male and a female become a mating pair for either life or a mating season (Mammal Group, 2014). Females have also been seen with several males in pursuit, as well as social living groups with numbers of around ten (Baker et al. 2004). These groups are thought to be extended family with a dominant breeding pair that gets assistance from the other subordinates when it comes to caring for the young. In solitary foxes the males follow the female that he shares or overlaps territory with. Foxes’ fur, primarily around the tail and muzzle regions, have the ability to secrete certain types of lipids. These serve as an attractant or scent for females and males to find each other (McLean et al. 2017). Also referred to as a musk gland, the odor released is primarily used for individual recognition which plays a role when choosing a mate (Saunders, 1988).

• Mating System
• monogamous monogamous
• polygynous polygynous
• cooperative breeder cooperative breeder

Fox species tend to breed from late December to late March, varying by species and habitat. Underground dens are built and lined with grass and other leaf litter to create a soft warm enclosure for the litter (Saunders, 1988). These dens are randomly spaced, occupied year after year, and are located in highly vegetated and covered areas (Meia and Weber, 1992). Litters are born in March and April after a gestation period lasting 7 to 8 weeks. Females have a litter annually ranging in size from 1 up to 11 pups, with most averaging 6. Foxes are born blind, opening their eyes after about 9 days, and start out with a grey coat. The litter is often divided between several dens to help with predator avoidance, and the pups spend time playing with each other until around 12 weeks when they are fully weaned and ready to join the parents on trips outside the den. By early fall the pups are ready to begin life on their own and travel away from their family den to have litters of their own (Saunders, 1988).

• Key Reproductive Features
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

Foxes provide a substantial amount of parental investment, ensuring the survival of their young after they are old enough to become independent. Once a female has mated, the first goal is finding a warm and safe den to raise her young (Mammal Group, 2014). The mating pair of foxes work as a team to raise the young, each parent playing a specific role. The female spends the majority of her time in the den nursing the litter so they are strong once fully weaned around the 12 week or 3 month mark (Saunders, 1988). Generally the male plays the providing role, bringing food to the den for the mother and eventually the litter to feed on. Offspring are able to join the parents after 12 weeks on hunting excursions where they will learn the skills it takes to survive and not go hungry (Saunders, 1988). Groups of foxes have shown signs of alloparental care, when other adult foxes assist with the care of young that are not their own. This has not been seen to increase the offspring survival, as it is possible that infanticide may occur in groups as well (Baker et al. 2014).

• Parental Investment
• male parental care male parental care
• female parental care female parental care

Lifespan/Longevity

Foxes in the wild have a span of only 2-4 years (National Geographic, 2018). In captivity they live on average 10-12 years depending on the species. The oldest fox recorded in captive history lived to be 21.3 years old (AnAge, 2017).

Behavior

The majority of fox species are solitary or nomadic, spending most of their lives alone, except during breeding season when they will have monogamous relationships with a mate (Rioux et al., 2017). Foxes are territorial animals, usually staying within a certain area. Migratory movements have been seen due to changing environments, primarily in the arctic where sea ice availability is hard to predict. Foxes characteristically stay in an area as long as food is available, but when resource abundance becomes depleted they are able to compensate by moving short to very long distances to find new resources (Lai et al., 2017). As population density of fox species increases there is also an increase in the formation of social groups being established. These groups consist of one dominant pair and a few other subordinate adults that tend to be related (Dorning and Harris, 2017). Breeding dens are where the cubs will first start to play with littermates and learn the basics of survival techniques from their parents (Saunders, 1988). It is key for fox parents to be present at the den as much as possible, their absence increases the chance of cub mortality by predators. Parental behavior and experience is important to prevent predation and increase the success of the offspring after they leave the den on their own (Erlandsson et al., 2017). Cubs develop a hierarchy within the den, sometimes leading to the actual death of a littermates. More dominant cubs have better access to food and often hold higher social status in the family or group (Harris, 2010). Foxes are opportunistic feeders that primarily feed on rodents using a distinct hunting technique. The pouncing technique, when the fox launches vertically into the air and comes down directly on their prey with force, is learned at an early age and allows the fox to kill their prey quickly. This technique helps ensure the kill and little to no fight with the prey, which will save energy and avoid any injury. Hunting is done for the foxes’ individual survival, unless they are currently raising young where both male and female will participate in providing food (New World Encyclopedia, 2017). In social groups foraging is shaped by competition with the dominant individuals taking advantage of the resources first. Foxes having such a broad diet is able to reduce the amount of competition seen in these groups (Dorning and Harris, 2017).

• Key Behaviors
• terricolous
• diurnal diurnal
• nocturnal nocturnal
• motile motile
• nomadic nomadic
• migratory migratory
• solitary solitary
• social social
• dominance hierarchies dominance hierarchies

Communication and Perception

Foxes are vocal animals. Unlike other canids they do not vocalize as a group. They use several different vocalizations to stay in contact with relatives because each individual has its own unique voice. A single voice is capable of spanning over a range of five octaves. The most well-known fox call is similar to a kind of bark that usually lasts for three to five syllables and resembles, “Wow-wow-wow”. This vocalization is used at all distances, is high pitched, and thought to be used as an identification system between individuals (Nosowitz, 2013). Another sound created by foxes is a basic alarm bark that consists of only one syllable. It is very sharp when heard at long distances, but is somewhat of a cough in close quarters. This is mainly used by parents to alarm pups of danger nearby. There is also a vocalization known as gekkering, which is a stuttering noise that resonates from the throat. This sound is mainly heard during mating season or during any aggressive interactions. Lastly there is the vixen’s wail or scream, a long, drawn-out, single note that is usually heard during breeding season. Thought originally to only be made by females in heat trying to call upon an available mate, it has also been observed being produced by males (Nosowitz, 2013). Foxes are also able to communicate their identities through the use of different scent/musk glands found the body including the muzzle and tail (Saunders, 1988). The tail itself can be used as a signal or flag to notify other foxes of their presence (National Geographic, 2018).

• Communication Channels
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• scent marks scent marks

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Foxes are in the order Carnivora but they are actually considered to be omnivores, consuming a wide range of food sources in their diet (New World Encyclopedia, 2017). This includes things such as carrion and small rodents to others such as berries, fruits, and seeds. Some of the most common prey items are mice, voles, and hares when hunting, but foxes are also known to steal the eggs of birds, and turtles or kill the young of other small mammals as a meal. Social groups may hunt cooperatively to surround prey, while individuals tend to cover an area over and over finding prey using their keen senses of smell and sound (Saunders, 1988).

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • eats eggs
  • scavenger scavenger
• herbivore herbivore
  • frugivore frugivore
  • granivore granivore
• omnivore omnivore

Predation

Adult foxes have very few predators besides for coyotes, bears, and wolves (Mammal Group and University of Bristol, 2014). The largest threat posed is by human hunting and trapping. The young face a broader range of threats from other small carnivores and many large birds of prey such as eagles, which is why they must remain in the den and out of sight for weeks (Saunders, 1988).

Ecosystem Roles

Foxes have two main ecosystem roles: the control of pests and small rodents and a role in seed dispersal due to their consumption of fruits and berries. Most introductions of fox species have been to control a species of small rodent that had become invasive and was affecting crop growth. In most of these cases fox were efficient at removing and minimizing the number of pests, while leaving the crops fully intact and unaffected (Saunders, 1988).

• Ecosystem Impact
• disperses seeds

Economic Importance for Humans: Positive

Foxes do not hold a very positive role in the human eye, except for their ability to adapt to new areas allowing for them to be introduced for pest management on farms and agricultural areas (New World Encyclopedia, 2017). Humans do raise foxes for their fur, it is the most popular seller second only to the American Mink ( Neovison vison ). Farms specialize on distinct color variants that are rarely found in the wild, and trade has expanded to be worldwide (Hoffman and Sillero-Zubiri, 2016).

• Positive Impacts
• pet trade pet trade
• controls pest population

Economic Importance for Humans: Negative

Foxes are considered a pest in most countries where they move into urban areas surviving on human waste, and have killed household pets of both dog and cat (Hoffman and Sillero-Zubiri, 2016). Although introductions have had positive effects in some areas, in Australia the introduction of foxes pushed many native species near extinction and could now even be considered invasive because of this. They also have negative effects on native fauna in some regions (New World Encyclopedia, 2017). Foxes are also carriers of several diseases such as rabies, canine distemper, and sarcoptic mange, which all help regulate mortality in the populations, but can create problems when living in such close proximity to humans who may own dogs that could easily acquire the disease if exposed (Saunders, 1988).

• Negative Impacts
• injures humans
  • carries human disease
• causes or carries domestic animal disease causes or carries domestic animal disease

Conservation Status

Currently the majority of true fox species are considered to be of least concern when it comes to conservation (Hoffman and Sillero-Zubiri, 2016). Foxes are still threatened by habitat loss, fragmentation, and exploitation which have a caused a decline in their numbers. Regarded as pests, foxes are unprotected in most countries where trapping and hunting in only regulated with the use of seasons and restrictions on methods of capture. Some countries see fox hunting as a sport, where groups will head out on foot to shoot and kill on a limited time basis. Farmers also shoot to kill on their land when foxes threaten their livestock and/or crops (Hoffman and Sillero-Zubiri, 2016). Hunting is the main threat to fox mortality due to a method known as culling that is used to control populations. Culling is the action of selective slaughter to reduce the population of a wild animal. This process will likely be able to drop population levels below carrying capacity, but will not put stress on the persistence of the species (Hoffman and Sillero-Zubiri, 2016).

Other Comments

Foxes are often kept in wildlife parks where do quite well due to their versatility and ability to adapt, yet they are quite shy (Hoffman and Sillero-Zubiri, 2016). Attempts at domesticating foxes has been in the works since the 1950's. Russian geneticist Dmitry K. Belyaev attempted to create the first tame fox population in Russia by using a specific breeding program. By selecting for the trait of "tame-ability" a small population of tame foxes has been born with noticeable changes in friendliness and some physical characteristics such as floppier ears (Jones, 2018). Since foxes hold a global presence they are quite often found in the history and culture of many nations and cultural groups (New World Encyclopedia, 2017). One association found in literature is between foxes and the ability of shape shifting. Primarily part of the Shinto religion, there are many stories where foxes will take the form of humans to trap other humans. This has also been seen in western literature and performances such as Janacek's opera, "The cunning little vixen" from 1922 (Mammal Group and University of Bristol, 2014).

Additional Links

Encyclopedia of Life

Contributors

Tru Hubbard (author), Colorado State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

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