The silver fox, sometimes referred to as the black fox, or blue fox, is a melanistic form of 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 ...

(''Vulpes vulpes''). Silver foxes display a great deal of pelt variation. Some are completely glossy black except for a white colouration on the tip of the tail, giving them a somewhat silvery appearance. Some silver foxes are bluish-grey, and some may have a cinereous colour on the sides. Historically, silver foxes were among the most valued fur-bearers, and their pelts were frequently worn by nobles in Russia, Western Europe, and China. Wild silver foxes do not naturally reproduce exclusively with members of the same coat morph and can be littermates with the common red variety, although captive populations bred for the blue fox fur and as pets are almost exclusively mated with members of the same colour.

Description

The silver fox's long outer hair can extend as much as beyond the shorter underfur on different parts of the fox's body, particularly under the throat, behind the shoulders, on the sides and the tail. The hair of the underfur is brown at the base, and silver-grey tipped with black further along the follicle. The hair is soft, glossy and was once reputed to be finer than that of the

pine marten The European pine marten (''Martes martes''), also known as the pine marten, is a mustelid native to and widespread in most of Europe, Asia Minor, the Caucasus, and parts of Iran, Iraq, and Syria. It is listed as Least Concern on the IUCN Red Lis ...

. The uniformly blackish brown or chocolate coloured underfur, which is unusually long and dense, measures in some places and is exceedingly fine. It surrounds the whole body even to the tail, where it is a little coarser and woollier. The fur is shortest on the forehead and limbs, and is finer on the fox's underbelly. When viewed individually, the hairs composing the belly fur exhibit a wavy appearance. There are scarcely any long hairs on the ears, which are thickly clothed with fur. The soles of the feet are so thickly covered with woolly hair that no callous spots are visible. Silver foxes tend to be more cautious than red foxes. When bred with another member of the same colour morph, silver foxes will produce silver-coated offspring, with little variation in this trend after the third generation. When mated to pure red foxes, the resulting cubs will be fiery red in overall coat colour, and will have blacker markings on the belly, neck and points than average red foxes. When one fiery red fox of such a pedigree is mated with a silver one, the litter is almost always 50% silver and 50% red, manifesting as a Mendelian incomplete dominant trait. Fiery red parents may occasionally produce a silver cub, the usual proportion being one in four. Occasionally, the colours of mixed foxes blend rather than segregate. The blended offspring of a silver and red fox is known as a cross fox. Dark colour in the Alaskan silver fox is caused by a mutation to MC1R, while in the standard silver fox the dark colour is caused by a recessive mutation to

agouti The agouti (, ) or common agouti is any of several rodent species of the genus ''Dasyprocta''. They are native to Central America, northern and central South America, and the southern Lesser Antilles. Some species have also been introduced else ...

Range

Red foxes, including the silvery form, are one of the most widely distributed carnivorous species in the world, ranging over much of the northern hemisphere and

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

. Their abundance in a wide variety of habitats can be attributed to introduction by humans into new habitats for fox-hunting. In

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 ...

, silver foxes occur mostly in the northeastern part of the continent. In the 19th century, silver foxes were sometimes collected from

Labrador Labrador () is a geographic and cultural region within the Canadian province of Newfoundland and Labrador. It is the primarily continental portion of the province and constitutes 71% of the province's area but is home to only 6% of its populatio ...

, the

Magdalen Islands The Magdalen Islands (, ) are a Canadian archipelago in the Gulf of St. Lawrence. Since 2005, the 12-island archipelago is divided into two municipalities: the majority-francophone Municipality of Îles-de-la-Madeleine and the majority-angloph ...

, and they were rarely taken from the mountainous regions of

Pennsylvania Pennsylvania, officially the Commonwealth of Pennsylvania, is a U.S. state, state spanning the Mid-Atlantic (United States), Mid-Atlantic, Northeastern United States, Northeastern, Appalachian, and Great Lakes region, Great Lakes regions o ...

and the wilder portions of

New York New York most commonly refers to: * New York (state), a state in the northeastern United States * New York City, the most populous city in the United States, located in the state of New York New York may also refer to: Places United Kingdom * ...

. They were occasionally found in Nova Scotia and New Brunswick. According to Sir John Richardson, it was uncommon for trappers to collect more than 4–5 silver foxes in any one season, in areas where silver foxes were present, despite the trappers' tendency to prioritize them above all other fur-bearers once they were discovered. Silver foxes comprise up to 8% of

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 ...

's red fox population. In the

former Soviet Union The post-Soviet states, also referred to as the former Soviet Union or the former Soviet republics, are the independent sovereign states that emerged/re-emerged from the dissolution of the Soviet Union in 1991. Prior to their independence, they ...

, silver foxes inhabit mostly the forest zones and forest–tundra belts, particularly the central and eastern parts of

Siberia Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...

and the

Caucasus The Caucasus () or Caucasia (), is a region spanning Eastern Europe and Western Asia. It is situated between the Black Sea and the Caspian Sea, comprising parts of Southern Russia, Georgia, Armenia, and Azerbaijan. The Caucasus Mountains, i ...

mountains. They are very rare in steppes and deserts.''Mammals of the Soviet Union'' Vol.II Part 1a, Sirenia and Carnivora (Sea cows; Wolves and Bears), V.G Heptner and N.P Naumov editors, Science Publishers, Inc. USA. 1998.

History of fur use

Pelt standards

For the pelt to be considered of suitable quality, certain criteria must be met: There must be a section of glossy black fur on the neck with a bluish cast. The silvery hairs must contain pure bands that are neither white nor prominent. The most valued furs had an even distribution of silvery hair, as patches of silvery hair gave the coat a flaky appearance, which was considered undesirable. The fur must have "silkiness", which refers to the softness of the fur, and was judged by a client running his hand over the pelt. The coat must have a sheen, which reflects the health of the coat and the animal from which it came, as well as the finesse of the hairs. The fur must weigh at least one pound, with value increasing along with size. Heavy fur is considered to be more durable and handsome.

In North America

The fur of a silver fox was once considered by the natives of

New England New England is a region consisting of six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the ...

to be worth more than 40

American beaver The North American beaver (''Castor canadensis'') is one of two extant beaver species, along with the Eurasian beaver (''Castor fiber''). It is native to North America and has been introduced in South America (Patagonia) and Europe (primarily Fi ...

skins. A chieftain accepting a gift of silver fox furs was seen as an act of reconciliation. The records of the

Hudson's Bay Company The Hudson's Bay Company (HBC), originally the Governor and Company of Adventurers of England Trading Into Hudson’s Bay, is a Canadian holding company of department stores, and the oldest corporation in North America. It was the owner of the ...

indicate that 19–25% of fox skins traded in

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

in the years 1825–1850 were silver, as were 16% of those traded in Labrador. The fur was almost always sold to Russian and Chinese traders.Robinson, H. M. ''The Great Fur Land; Or, Sketches of Life in the Hudson's Bay Territory'', BiblioBazaar, LLC, 2009. The silver fur of this fox was the most sought-after pelt due to its colour and style. In 1830, the

allele frequency Allele frequency, or gene frequency, is the relative frequency of an allele (variant of a gene) at a particular locus in a population, expressed as a fraction or percentage. Specifically, it is the fraction of all chromosomes in the population tha ...

for a silver pelt was at 15% but due to overhunting, this number had fallen to 5% in 1930. The silver pelt is still hunted for and the population of foxes with this silver pelt continues to fall. Before the practice of

fur farming Fur farming is the practice of breeding or raising certain types of animals for their fur. Most of the world's farmed fur was produced by European farmers. In 2018, there were 5,000 fur farms in the EU, located across 22 countries; these area ...

was eventually refined on

Prince Edward Island Prince Edward Island is an island Provinces and territories of Canada, province of Canada. While it is the smallest province by land area and population, it is the most densely populated. The island has several nicknames: "Garden of the Gulf", ...

, it was standard practice to release free-ranging silver foxes into small islands, where they quickly starved to death. Fur farmers on Prince Edward Island gained success by breeding and caring for their foxes in captivity. Charles Dalton and Robert Oulton began crossbreeding experiments in 1894. The farmers recognized the foxes' monogamous habits and permitted their studs to mate for life with a single female, contributing to their success. The fur of captive-bred foxes was of better quality than that of free-ranging ones (worth $500–1,000 rather than $20–30) because of improved care and diet. These silver foxes were bred strictly with members of their own colour morph, and by the third generation, all residual traces of red or cross ancestry disappeared. The silver fox price boom in North America ended in 1914, but by 1921, there were 300 farms throughout the USA. A well-known silver fox ranch of

was that of Fred Colpitts from Salisbury,

New Brunswick New Brunswick is a Provinces and Territories of Canada, province of Canada, bordering Quebec to the north, Nova Scotia to the east, the Gulf of Saint Lawrence to the northeast, the Bay of Fundy to the southeast, and the U.S. state of Maine to ...

. Known as the "Colpitts Brothers", Fred and James raised silver foxes in the early 1920s and used selective breeding to refine the fox colour. Fred developed the Platinum fox (a colour variation of the silver fox) that was recognized for its unique colour and markings worldwide. These Platinum foxes brought top dollar from sales in

Montreal Montreal is the List of towns in Quebec, largest city in the Provinces and territories of Canada, province of Quebec, the List of the largest municipalities in Canada by population, second-largest in Canada, and the List of North American cit ...

and London, with one pair of foxes selling for $5000, and winning major awards at shows across

, the two brothers sold foxes for breeding stock throughout

. In the 1930s, scientific advances led to increases in fox health. The Fromm brothers funded the development of the distemper vaccine and vitamin D tablets to prevent the foxes from getting rickets. They also allowed the foxes to roam relatively free as they would otherwise damage their pelts and they were fed daily. The largest silver fox the Fromms' had was over .Laut, Agnes C. ''The Fur Trade of America'', Kessinger Publishing, 2004.

In Eurasia

Silver foxes in Russian fur farms are of North American stock, and are selectively bred in order to remove as much brown from the fur as possible, as the presence of brown fur lowers the pelt's value.

Estonia Estonia, officially the Republic of Estonia, is a country in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea across from Sweden, to the south by Latvia, and to the east by Ru ...

began farming silver foxes in 1924, after receiving 2,500 foundation specimens from Norway to Mustajõe farm. The numbers of Estonian silver fox farms steadily increased in the following decades. During the

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

period, the silver fox industry boomed due to government subsidies and a focus on selectively breeding foxes for greater fertility than fur quality.

Behaviour

The silver fox morph is behaviourally similar to the red morph. One common behaviour is

scent marking In ethology, territory is the sociographical area that an animal consistently defends against conspecific competition (or, occasionally, against animals of other species) using agonistic behaviors or (less commonly) real physical aggression. ...

. This behaviour is used as a display of dominance, but may also be used to communicate the absence of food from foraging areas as well as social records.

Mating behaviour

Silver foxes exist in seasonally

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. ...

pairs for the breeding months of December to April, and most matings occur in January and February. Female silver foxes are monestrous (having one estrus cycle per year) with

estrus The estrous cycle (, originally ) is a set of recurring physiological changes induced by reproductive hormones in females of mammalian subclass Theria. Estrous cycles start after sexual maturity in females and are interrupted by anestrous phas ...

lasting 1–6 days and

parturition Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the f ...

occurring after about 52 days of

gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregn ...

. During or approaching estrus, the vulva of silver foxes increases in size and

tumescence Tumescence is the quality or state of being tumescent or swollen. Tumescence usually refers to the normal engorgement with blood ( vascular congestion) of the erectile tissues, marking sexual excitation, and possible readiness for sexual activity. ...

, indicating the sexual readiness or condition of the fox. Female silver foxes generally breed during their first autumn, but a number of factors contribute to their breeding success. These include age, food, population density, and the

mating system A mating system is a way in which a group is structured in relation to sexual behaviour. The precise meaning depends upon the context. With respect to animals, the term describes which males and females mating, mate under which circumstances. Reco ...

(

polygyny Polygyny () is a form of polygamy entailing the marriage of a man to several women. The term polygyny is from Neoclassical Greek πολυγυνία (); . Incidence Polygyny is more widespread in Africa than in any other continent. Some scholar ...

monogamy Monogamy ( ) is a social relation, relationship of Dyad (sociology), two individuals in which they form a mutual and exclusive intimate Significant other, partnership. Having only one partner at any one time, whether for life or #Serial monogamy ...

). Higher population density leads to a higher incidence of failure in producing pups. Silver foxes have litters that typically range from 1 to 14 pups, with the average being 3 to 6 pups. Litter size generally increases with age and abundance of food. Scientists have observed an increase in reproductive success with age in silver fox morphs, which may be attributable to yearlings breeding an average of nine days after adults. Success in larger litters depends highly on the availability of extra-parental care via the assistance of unmated females. This is especially the case in higher density populations, where some females fail to produce pups. Silver foxes engage in a system of bi-parental care, which is associated with their seasonal monogamous mating scheme. For a given litter, males contribute a large investment in the offspring by both feeding and protecting the den. While the pups are early in development, the male secures food for the nursing vixen. Whereas males are more vigilant in defending the den, females also defend their offspring aggressively.

Competition capacity

In captivity, differential reproductive success can be attributed to variation in the competition capacity among individual females. Competition capacity is defined as the ability of individuals to dominate resources such as food or nesting sites. The competition capacity of the mother directly influences the fitness of her offspring. In one experiment where vixens (whose competition capacities were categorized as high, medium, or low) were bred under standard farming conditions, competition capacity was positively associated with the number of healthy offspring raised to weaning. The findings have led to the use of competition capacity as a more encompassing measure of reproductive fitness for the silver fox, and the revelation that some vixens engage in

infanticide Infanticide (or infant homicide) is the intentional killing of infants or offspring. Infanticide was a widespread practice throughout human history that was mainly used to dispose of unwanted children, its main purpose being the prevention of re ...

. The vixens generated more weaned cubs during their next reproductive cycle than those who did not engage in infanticide. This may suggest the conservation of efforts or investment to increase future reproductive success. Infanticidal vixens infrequently adopt and help to raise the young of neighboring vixens after eating their own.

Feeding

While silver foxes are opportunistic feeders and will consume any food presented to them, they prefer a more carnivorous diet when meat is available. When meat is scarce, they rely more heavily on plant material. Like the red morph, the silver fox adapts different strategies when hunting different prey. When hunting smaller mammals, the foxes adopt a "mousing position" from which they can locate prey based on sound. They launch themselves, pin prey to the ground using their forepaws, and kill it by biting. Quicker terrestrial prey requires more practiced behaviour, often involving stalking and rapid pursuit. When prey escapes to hidden caches or burrows, foxes are known to occasionally nap beside the entrances and lie in wait for prey to reemerge.

Domestication

The

domesticated silver fox The domesticated silver fox (''Vulpes vulpes'' forma ''amicus'') is a form of the silver fox that has been to some extent domesticated under laboratory conditions. The silver fox is a melanistic form of the wild red fox. Domesticated silver fox ...

is a form of the silver fox which has been

domesticated Domestication is a multi-generational mutualistic relationship in which an animal species, such as humans or leafcutter ants, takes over control and care of another species, such as sheep or fungi, to obtain from them a steady supply of reso ...

—to some extent—under laboratory conditions. Domesticated silver foxes are the result of an experiment which was designed to demonstrate the power of

selective breeding Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant m ...

to transform species, as described by

Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English Natural history#Before 1900, naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all speci ...

in ''

On the Origin of Species ''On the Origin of Species'' (or, more completely, ''On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life'')The book's full original title was ''On the Origin of Species by M ...

''. The experiment explored whether selection for behaviour rather than

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

may have been the process that had produced

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. ...

s from

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 ...

, by recording the changes in foxes when in each generation only the most

tame Tame may refer to: *Taming, the act of training wild animals * River Tame, Greater Manchester *River Tame, West Midlands and the Tame Valley * Tame, Arauca, a Colombian town and municipality * "Tame" (song), a song by the Pixies from their 1989 a ...

foxes were allowed to breed. Many of the descendant foxes became both tamer and more dog-like in morphology, including displaying mottled or spotted coloured fur.

In culture

The silver fox appears in the stories of many cultures. The

Achomawi Achomawi (also Achumawi, Ajumawi and Ahjumawi) are the northerly nine (out of eleven) bands of the Pit River tribe of Palaihnihan Native Americans who live in what is now northeastern California in the United States. These 5 autonomous bands ( ...

people of Northern California tell a myth about two creators: the wise silver fox stemming from fog and the amoral trickster coyote from the clouds. The myth reveals that while the coyote slept, the silver fox used its hair combings to create landmasses. It then thought of trees, rocks, fruits, and other resources, and created those too. However, the coyote could not employ self-control and ate everything up at will after it awoke. The story tells a moral lesson, portraying the silver fox as a wise being and creator of sorts while suggesting the coyote as a lazy, greedy and impulsive animal. Similarly, the silver fox has often been represented on totem poles. The silver fox also appears as a symbol on the

coat of arms. In the late 1800s, the rare silver fox was native to the region, and its pelt was highly valued around the world. Scientific developments for breeding fur-bearing animals took place on the island. Fur farming became an important part of the 20th century economy of the province and Wisconsin. The Fromm brothers started their fur trading company in Central Wisconsin in the 1930s, which led to the development of the distemper vaccine. The silver fox has come to symbolize the wit and wisdom of the islanders. Its fur-breeding history resulted in its status as a symbol for the ingenuity and perseverance involved in the industry. The silver fox has also been represented in different forms of media. On television, in films, and in comic books, Silver Fox is a character in the

Wolverine The wolverine ( , ; ''Gulo gulo''), also called the carcajou or quickhatch (from East Cree, ''kwiihkwahaacheew''), is the largest land-dwelling species, member of the family Mustelidae. It is a muscular carnivore and a solitary animal. The w ...

superhero series. In cartoon, the characters Scarface, Lady Blue and their children from TV animated series '' The Animals of Farthing Wood'' are silver foxes. The term ''silver fox'' is used to describe an attractive older man, specifically one who has (or is beginning to show) grey hair. The name "Silver Fox" was used on LNER A4 steam locomotive no 2512 (later BR no 60017), designed by

Sir Nigel Gresley Sir Herbert Nigel Gresley (19 June 1876 – 5 April 1941) was a British railway engineer. He was one of Britain's most famous steam locomotive engineers, who rose to become Chief Mechanical Engineer (CME) of the London and North Eastern Rail ...

References

External links

The Domestic fox

website from Cornell University with detailed information (videos and articles)

in ''

The New York Times ''The New York Times'' (''NYT'') is an American daily newspaper based in New York City. ''The New York Times'' covers domestic, national, and international news, and publishes opinion pieces, investigative reports, and reviews. As one of ...

''
Nice Rats, Nasty Rats: Maybe It's All in the Genes
''New York Times''
CBBC News Article

The Fox Farm Experiment
{{Webarchive, url=https://web.archive.org/web/20100215131052/http://www.hum.utah.edu/~bbenham/2510%20Spring%2009/Behavior%20Genetics/Farm-Fox%20Experiment.pdf , date=2010-02-15 , ''American Scientist''
"New Nice"
WNYC RadioLab Story; contains audio, video, interviews, and other links. (Public Radio)
Soviet Scientist Turns Foxes Into Puppies
* Horizon S48E08 (2010): The Secret Life of the Dog - BBC * Explorer: How Man Tamed the Wild - National Geographic
"Silver Fox Farm" (Denver, Colorado)
British Pathé film (Part of a "Walter Futter's Curiosities" film), 1930. Vulpes Fox, Silver Fox, Silver Fox, Silver