Crab-eating Fox
Encyclopedia
The crab-eating fox also known as the forest fox, wood fox, and the common fox, is an extant species of medium-sized canid
endemic to the central part of South America
and which appeared during the Pliocene
epoch. Cerdocyon comes from the Greek words kerdo (meaning fox) and cyon (dog) referring to the dog and fox- like characters of this animal.
which appeared around 6.0 Ma in North America
as Cerdocyon avius
becoming extinct by around 1.4—1.3 Ma. living about . This genus carried on in South America from an undetermined time, possibly around 3.1 Ma and continues to present in the form or similar to the crab-eating fox.
As one of the species of the tribe Canini, it is related to the Canis genus. It was theorized at present that the crab-eating fox's nearest relative is the Short-eared Dog
. This, however, has to be supported by mitochondrial investigations (Pietrzak, 2007). Two subgenera (Atelocynus and Speothos) were long ago included in Cerdocyon.
s, woodland
s subtropical forests, prickly, shrubby thickets and tropical savannas such as the caatinga
, llanos
and campo
. from Colombia
and southern Venezuela
to Paraguay
, Uruguay
and Northern Argentina
. (Eisenberg, 1999)
Its habitat also includes wooded river banks such as Riparian forest
. In the rainy season their range moves uphill, whilst in drier times they move to low ground (Nowak, 1999). Their habitat covers all environments except rainforests, high mountains and open grassy savannas. In some regions of their range they are threatened with extinction.
, spending its day in dens that were dug by different animals. It hunts individually or lives in pairs, it eats crabs, lizards and different flying animals. It is easy to domesticate and farm, but its fur is not so highly valued as that of other species.
Short and thick fur. Coloration varies from grey - brown, to yellow air raid, to pale, navy-blue spotted, to dark grey. There is a black streak along the back legs with a black stripe along the back. On muzzle, ears and paws there is more reddish fur. Tail, legs and ear tips are black. The torso is somewhat narrow with strong short legs. The dense hairy tail stays upright when they are excited. The ears are wide and round.
teams, or small groups which hunt with several teams during the reproductive season. The population distribution is as follows: some explorers show one individual distribution for 4 km2. Berta (1982) shows one had changed from 0,6 to 0,9 km2 for one individual. Territorialism
was noticed during the dry time; during rainy seasons, when there is more food, they pay less attention to territory (Nowak, 1999). Hideouts and dens often are founded in bushes and in thick grass, and there are several entrance holes. Despite being capable of tunnelling, they prefer to take over other animals' burrows. Hunting methods are adapted to type of prey. Several characteristic sounds are made by the crab-eating fox such as barking, whirring and howling, which occur often when pairs lose contact. Greetings include: tail waving, rolling over or folding the ears flat in a subordinate gesture. Returning group members begin a ritual of sniffing, tail lifting and mutual licking.
s during the wet season giving this animal its common name. It is an opportunist and an omnivore preferring insects or meat from rodents and birds when available. Other foods readily consumed include turtle eggs, tortoises, fruit, eggs
, crustacean
s, insects, lizards, crabs and carrion
. Field analysis shows a food distribution of 25% rodents, 24.1% reptiles, 0.6% marsupials, 0.6% rabbits, 10.3% birds, 35.1% amphibians and 5.2% fish. Different studies during the rainy season in Venezuela showed a distribution of 54% insects and 20% vertebrates, changing in the dry season to 48% vertebrates, 31% crabs and 16% insects. Their diet is varied and differs in different investigations, suggesting opportunistic feeding and geographical variation. During the wet season
the diet contains more crabs and crustaceans, while during the dry season
it contains more insects (Berta, 1982; Pietrzak, 2007). The crab-eating fox contributes to the control of rodents and harmful insects.
is not valuable. The fox does not pose a danger to livestock. This is not currently a species of concern for conservation; however, its habitat is slowly shrinking due to human forces such as agriculture, as well as feral
dog
s' encroachment on its territory, though the population is still stable. Despite the low value of their pelts, these canids can often be killed by locals, though there have been no unambiguous proof that they attack farm animals. They are easy to domesticate, and often bred by local people. This does not, however, remove the threat to their population. The species is not protected at present. Despite this, they are in danger from a shrinking habitat through agricultural activity, as well as from feral dogs which can pose a threat for a number of species.
".
, differing in sizes and coloring of fur (Bisbal, 1988).
Canidae
Canidae is the biological family of carnivorous and omnivorous mammals that includes wolves, foxes, jackals, coyotes, and domestic dogs. A member of this family is called a canid . The Canidae family is divided into two tribes: Canini and Vulpini...
endemic to the central part of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
and which appeared during the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. 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...
epoch. Cerdocyon comes from the Greek words kerdo (meaning fox) and cyon (dog) referring to the dog and fox- like characters of this animal.
Origin
Cerdocyonina is a tribeTribe (biology)
In biology, a tribe is a taxonomic rank between family and genus. It is sometimes subdivided into subtribes.Some examples include the tribes: Canini, Acalypheae, Hominini, Bombini, and Antidesmeae.-See also:* Biological classification* Rank...
which appeared around 6.0 Ma in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
as Cerdocyon avius
Cerdocyon avius
Cerdocyon avius is an extinct species of omnivorous mammal of the family Canidae, which inhabited North America during the Pliocene from 4.9 Ma to approximately 11,000 years ago. It is similar to the modern Crab-eating Fox.-Taxonomy:...
becoming extinct by around 1.4—1.3 Ma. living about . This genus carried on in South America from an undetermined time, possibly around 3.1 Ma and continues to present in the form or similar to the crab-eating fox.
As one of the species of the tribe Canini, it is related to the Canis genus. It was theorized at present that the crab-eating fox's nearest relative is the Short-eared Dog
Short-eared Dog
The short-eared dog , also known as the short-eared fox or the short-eared zorro, is a unique and elusive canid species endemic to the Amazonian basin...
. This, however, has to be supported by mitochondrial investigations (Pietrzak, 2007). Two subgenera (Atelocynus and Speothos) were long ago included in Cerdocyon.
Habitat
The crab-eating fox is a canid that ranges in savannaSavanna
A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.Some...
s, woodland
Woodland
Ecologically, a woodland is a low-density forest forming open habitats with plenty of sunlight and limited shade. Woodlands may support an understory of shrubs and herbaceous plants including grasses. Woodland may form a transition to shrubland under drier conditions or during early stages of...
s subtropical forests, prickly, shrubby thickets and tropical savannas such as the caatinga
Caatinga
Caatinga is a type of vegetation, and an ecoregion characterized by this vegetation in the northeastern part of Brazil. The name "Caatinga" is a Tupi word meaning "white forest" or "white vegetation"...
, llanos
Llanos
The Llanos is a vast tropical grassland plain situated to the east of the Andes in Colombia and Venezuela, in northwestern South America. It is an ecoregion of the Flooded grasslands and savannas Biome....
and campo
Campo
Campo is Italian, Portuguese and Spanish for "field".In the city of Venice the word Campo designs a square, regardless of her size; Piazza San Marco is the only exception being the only urban space called a piazza instead of Campo....
. from Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
and southern Venezuela
Venezuela
Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
to Paraguay
Paraguay
Paraguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...
, Uruguay
Uruguay
Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
and Northern Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. (Eisenberg, 1999)
Its habitat also includes wooded river banks such as Riparian forest
Riparian forest
A riparian forest is a forested area of land adjacent to a body of water such as a river, stream, pond, lake, marshland, estuary, canal, sink or reservoir. -Etymology:...
. In the rainy season their range moves uphill, whilst in drier times they move to low ground (Nowak, 1999). Their habitat covers all environments except rainforests, high mountains and open grassy savannas. In some regions of their range they are threatened with extinction.
Taxonomy and evolution
Cerdocyon thous, Cerdocyon avius and other species of the genus Cerdocyon underwent radiational evolution on the South American continent (Pietrzak, 2007). All relatives of the crab-eating fox (Cerdocyon thous) are extinct. It is the only representative at present of the genus Cerdocyon. Genetically there are 74 diploid chromosomes (36 pairs).Appearance
The crab-eating fox is predominantly greyish-brown with areas of red on the face and legs, and black-tipped ears and tail. It has short, strong legs and its tail is long and bushy. It may reach an adult weight of 10 to 17 lb (4.5 to 7.7 kg). The head and body length averages 64.3 centimetres (25.3 in) and the average tail length is 28.5 centimetres (11.2 in) (Berta, 1982). This fox weighs between 5 to 8 kg (11 to 17.6 lb) (A. Hover; C Yahnke, 2003). It is mainly nocturnal and also is active at duskDusk
Dusk is the beginning of darkness in the evening, and occurs after twilight, when the sky generally remains bright and blue. Civil dusk is when the earth has rotated enough that the center of the sun is at 6° below the local horizon...
, spending its day in dens that were dug by different animals. It hunts individually or lives in pairs, it eats crabs, lizards and different flying animals. It is easy to domesticate and farm, but its fur is not so highly valued as that of other species.
Short and thick fur. Coloration varies from grey - brown, to yellow air raid, to pale, navy-blue spotted, to dark grey. There is a black streak along the back legs with a black stripe along the back. On muzzle, ears and paws there is more reddish fur. Tail, legs and ear tips are black. The torso is somewhat narrow with strong short legs. The dense hairy tail stays upright when they are excited. The ears are wide and round.
Life cycle and behaviour
Crab-eating fox creates monogamicMonogamy
Monogamy /Gr. μονός+γάμος - one+marriage/ a form of marriage in which an individual has only one spouse at any one time. In current usage monogamy often refers to having one sexual partner irrespective of marriage or reproduction...
teams, or small groups which hunt with several teams during the reproductive season. The population distribution is as follows: some explorers show one individual distribution for 4 km2. Berta (1982) shows one had changed from 0,6 to 0,9 km2 for one individual. Territorialism
Territorialism
Territorialism, also known as Statism , was a Jewish political movement calling for creation of a sufficiently large and compact Jewish territory , not necessarily in the Land of Israel and not necessarily fully autonomous.-Development of territorialism:Before 1905 some Zionist leaders took...
was noticed during the dry time; during rainy seasons, when there is more food, they pay less attention to territory (Nowak, 1999). Hideouts and dens often are founded in bushes and in thick grass, and there are several entrance holes. Despite being capable of tunnelling, they prefer to take over other animals' burrows. Hunting methods are adapted to type of prey. Several characteristic sounds are made by the crab-eating fox such as barking, whirring and howling, which occur often when pairs lose contact. Greetings include: tail waving, rolling over or folding the ears flat in a subordinate gesture. Returning group members begin a ritual of sniffing, tail lifting and mutual licking.
Reproduction
The adult female gives birth to one or two litters per year, and the breeding pair is monogamous. The pair ranges the plains together. As a tropical animal, reproduction is not fixed to certain times of year, and takes place twice yearly. The reproductive period most often begins in November or December, and July. The birth of offspring follows after a 56-day gestation, typically in January, February or sometimes March (Nowak, 1999). The number of cubs varies from three to six (Mendel, 1988). Newborns are toothless and blind (Berta, 1982). The eyes open after about fourteen days, and solid food is taken from thirty days after birth. Lactation lasts approximately 90 days (Nowak, 1999). The cubs' fur is dark gray above with a brighter underbelly. Both adult males and females look after cubs. From about twenty days, the cubs' fur becomes more like adults' coats, completing around thirty-five days. Sexual maturity occurs after nine months, after which territories are marked with urine (Berta, 1982; Mendel, 1988).Diet
The crab-eating fox searches for crabs on muddy floodplainFloodplain
A floodplain, or flood plain, is a flat or nearly flat land adjacent a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge...
s during the wet season giving this animal its common name. It is an opportunist and an omnivore preferring insects or meat from rodents and birds when available. Other foods readily consumed include turtle eggs, tortoises, fruit, eggs
Egg (food)
Eggs are laid by females of many different species, including birds, reptiles, amphibians, and fish, and have probably been eaten by mankind for millennia. Bird and reptile eggs consist of a protective eggshell, albumen , and vitellus , contained within various thin membranes...
, crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s, insects, lizards, crabs and carrion
Carrion
Carrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
. Field analysis shows a food distribution of 25% rodents, 24.1% reptiles, 0.6% marsupials, 0.6% rabbits, 10.3% birds, 35.1% amphibians and 5.2% fish. Different studies during the rainy season in Venezuela showed a distribution of 54% insects and 20% vertebrates, changing in the dry season to 48% vertebrates, 31% crabs and 16% insects. Their diet is varied and differs in different investigations, suggesting opportunistic feeding and geographical variation. During the wet season
Wet season
The the wet season, or rainy season, is the time of year, covering one or more months, when most of the average annual rainfall in a region occurs. The term green season is also sometimes used as a euphemism by tourist authorities. Areas with wet seasons are dispersed across portions of the...
the diet contains more crabs and crustaceans, while during the dry season
Dry season
The dry season is a term commonly used when describing the weather in the tropics. The weather in the tropics is dominated by the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year...
it contains more insects (Berta, 1982; Pietrzak, 2007). The crab-eating fox contributes to the control of rodents and harmful insects.
Threats
This fox is occasionally hunted, but the peltFur
Fur is a synonym for hair, used more in reference to non-human animals, usually mammals; particularly those with extensives body hair coverage. The term is sometimes used to refer to the body hair of an animal as a complete coat, also known as the "pelage". Fur is also used to refer to animal...
is not valuable. The fox does not pose a danger to livestock. This is not currently a species of concern for conservation; however, its habitat is slowly shrinking due to human forces such as agriculture, as well as feral
Feral
A feral organism is one that has changed from being domesticated to being wild or untamed. In the case of plants it is a movement from cultivated to uncultivated or controlled to volunteer. The introduction of feral animals or plants to their non-native regions, like any introduced species, may...
dog
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s' encroachment on its territory, though the population is still stable. Despite the low value of their pelts, these canids can often be killed by locals, though there have been no unambiguous proof that they attack farm animals. They are easy to domesticate, and often bred by local people. This does not, however, remove the threat to their population. The species is not protected at present. Despite this, they are in danger from a shrinking habitat through agricultural activity, as well as from feral dogs which can pose a threat for a number of species.
Status of conservation
The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) lists the fox as not threatened by extinction - Appendix II (CITES, 2000). The IUCN lists the crab-eating fox as "Least ConcernLeast Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
".
Subspecies
The crab-eating fox has five recognized subspeciesSubspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
, differing in sizes and coloring of fur (Bisbal, 1988).
- C. t. thous, VenezuelaVenezuelaVenezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
, GuyanaGuyanaGuyana , officially the Co-operative Republic of Guyana, previously the colony of British Guiana, is a sovereign state on the northern coast of South America that is culturally part of the Anglophone Caribbean. Guyana was a former colony of the Dutch and of the British...
, Surinam, French GuianaFrench GuianaFrench Guiana is an overseas region of France, consisting of a single overseas department located on the northern Atlantic coast of South America. It has borders with two nations, Brazil to the east and south, and Suriname to the west...
North Brasil. - C. t. azarae, North Brasil.
- C. t. entrerianus, Brasil, BoliviaBoliviaBolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
.UruguayUruguayUruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
, ParaguayParaguayParaguay , officially the Republic of Paraguay , is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Paraguay lies on both banks of the Paraguay River, which runs through the center of the...
and ArgentinaArgentinaArgentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
. - C. t. aquilus, north VenezuelaVenezuelaVenezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
and ColombiaColombiaColombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
. - C. t. germanus, BogotáBogotáBogotá, Distrito Capital , from 1991 to 2000 called Santa Fé de Bogotá, is the capital, and largest city, of Colombia. It is also designated by the national constitution as the capital of the department of Cundinamarca, even though the city of Bogotá now comprises an independent Capital district...
region (ColombiaColombiaColombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
).