The crab-eating fox is omnivorous. In one study their diet included 25.3% small mammals, 24.1% reptiles, 0.6% marsupials, 0.6% rabbits, 10.3% birds, 35.1% amphibians, and 5.2% fish (Medel, 1988). However, in other studies (see Berta, 1982) the porportion of animals consumed is different, suggesting an opportunistic feeding behavior, and they may shift their food habits seasonally. During the wet season in the low llanos, crabs and other crustaceans are consumed, whereas during the dry season their diet contained more insects (Berta, 1982).
Animal Foods: birds; mammals; amphibians; reptiles; fish; insects; terrestrial non-insect arthropods; aquatic crustaceans
Primary Diet: carnivore (Eats terrestrial vertebrates, Insectivore , Eats non-insect arthropods)
Predation upon this species has not been reported.
Generally, the crab-eating fox resembles the size and shape of most foxes. The coat is gray-brown on dorsally, with the face, ears, and legs reddish. The throat and underside of C. thous is white. The tips of the ears, tail, and legs are black. C. thous has short, robust legs. The head and body length averages 643 mm and the average tail length is 285 mm (Berta, 1982). These foxes weigh between five and eight kg.
Range mass: 5 to 8 kg.
Average length: 643 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Average basal metabolic rate: 8.502 W.
In captivity the crab-eating fox has been known to live up to eleven years six months (Nowak, 1999).
Range lifespan
Status: captivity: 11 (high) years.
Average lifespan
Status: captivity: 11.5 years.
The habitat of C. thous includes mostly savannahs and woodlands, however this species is known to inhabit a variety of other areas including edge and forested areas (Eisenberg, 1999). These foxes may use higher ground during the rainy season, and lowlands during the dry season (Nowak, 1999).
Habitat Regions: tropical
Terrestrial Biomes: forest
The crab-eating fox (Cerdocyon thous) is distributed from Colombia and Venezuela south to Paraguay, Uruguay and Northern Argentina (Eisenberg, 1999).
Biogeographic Regions: neotropical (Native )
Because of its role as a predator, C. thous may help to control populations of small mammals, insects, fish, and crabs.
Although the pelt is worth little, the crab-eating fox is hunted intensively (Berta, 1982).
There is little evidence that C. thous impacts the local livestock, however the animal is often shot by local farmers and ranchers (Canid Specialist Group, 1995).
See Reproduction.
C. thous is listed in CITES Appendix II (CITES, 2000), but the Argentine Wildlife board has declared the crab-eating fox out of danger (Canid Specialist Group, 1998).
CITES: appendix ii
IUCN Red List of Threatened Species: least concern
Perception Channels: tactile ; chemical
C. thous was formerly known as Dusicyon thous. C. thous is a monotypic species but formerly the subgenera Atelocynus and Speothos were included in Cerdocyon.
Cerdocyon thous is derived from three Greek words kerdo (fox), cyon (dog) and thoos (jackel). The word 'zorro' is spanish for fox. Other common names include Zorro del Monte, Azara's Fox and Zorro Perro (Berta,1982; Canid Specialist Group, 1998).
Captive crab-eating foxes are monogamous and often breed twice per year in intervals of 7 to 8 months with a possible peak in births during January or February (Berta, 1982).
Mating System: monogamous
Breeding in C. thous takes place throughout the year, but peaks November or December (Canid Specialist Group, 1998). The gestation period of C. thous averages 56 days, leading to a peak of births in January and February (Nowak, 1999). Females produce between 3 and 6 pups per litter (Medel, 1988). Captive females have been known to reproduce twice annually, although information for wild crab-eting foxes is not available. At birth, C. thous pups weigh between 120 and 160 grams. They are born without teeth, and their eyes and ears closed (Berta, 1982). The eyes of the newborns open at 14 days, and they start digesting solid food at 30 days. Pups are weaned at 90 days (Nowak, 1999). The pups' coats are charcoal grey with a yellowish-brown patch on the lower abdomen. Twenty days after birth the pelage starts to change, and by the 35th day pups show adult pelage (Berta, 1982). Sexual maturity is reached by the first year. Raised leg urination (in both sexes) is indicative of sexual maturity in C. thous (Berta,1982; Medel, 1988).
Breeding season: Peak breeding occurs in November and December.
Range number of offspring: 3 to 6.
Average number of offspring: 4.
Range gestation period: 52 to 59 days.
Average gestation period: 56 days.
Average weaning age: 90 days.
Average age at sexual or reproductive maturity (female): 9 months.
Average age at sexual or reproductive maturity (male): 9 months.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous
Average birth mass: 140 g.
Average number of offspring: 4.
Average age at sexual or reproductive maturity (male)
Sex: male: 274 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 274 days.
The female nurses the young for about 90 days. When solid food is ingested (around 30 days) both parents bring the young food. Both parents guard the young (Nowak, 1999).
Parental Investment: altricial ; male parental care ; female parental care
The crab-eating fox (Cerdocyon thous), also known as the forest fox, wood fox, bushdog (not to be confused with the bush dog) or maikong, is an extant species of medium-sized canid endemic to the central part of South America since at least the Pleistocene epoch.[1][2][4] Like South American foxes, which are in the genus Lycalopex, it is not closely related to true foxes. Cerdocyon comes from the Greek words kerdo (meaning fox) and kyon (dog) referring to the dog- and fox-like characteristics of this animal.[5]
The crab-eating fox was originally described as Canis thous by Linnaeus (1766), and first placed in its current genus Cerdocyon by Hamilton-Smith in 1839.[4]
Cerdocyonina is a tribe which appeared around 6.0 million years ago (Mya) in North America as Ferrucyon avius becoming extinct by around 1.4–1.3 Mya. living about 4.7 million years. This genus has persisted in South America from an undetermined time, possibly around 3.1 Mya, and continues to the present in the same or a similar form to the crab-eating fox.[6]
As one of the species of the tribe Canini, it is related to the genus Canis. The crab-eating fox's nearest living relative, as theorized at present, is the short-eared dog. This relationship, however, has yet to be supported by mitochondrial investigations. Two subgenera (Atelocynus and Speothos) were long ago included in Cerdocyon.
Cerdocyon thous, C. avius and other species of the genus Cerdocyon underwent radiational evolution on the South American continent.[7] All close relatives of the crab-eating fox (Cerdocyon thous) are extinct. It is the only living representative at present of the genus Cerdocyon.
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. The head and body length averages 64.3 centimetres (25.3 in), and the average tail length is 28.5 centimetres (11.2 in).[8] It can weigh between 10 to 17 pounds (4.5 to 7.7 kg).[9][10]
The coat is short and thick. Coloration varies from grey to brown, to yellowish, to pale, to dark grey. There is a black streak along the back legs, with a black stripe along the spine. On muzzle, ears and paws there is more-reddish fur. The tail, legs and ear tips are black. The ears are wide and round. The torso is somewhat narrow; legs are short but strong. The dense hairy tail stays upright when they are excited. There is significant variation in color between population, from very dark to light grey-yellow.[4]
Genetically, there are 74 diploid chromosomes (36 pairs).
The crab-eating fox is a canid that ranges in savannas; woodlands; subtropical forests; prickly, shrubby thickets; and tropical savannas such as the caatinga, plains, and campo, from Colombia and southern Venezuela in the north to Paraguay, Uruguay and northern Argentina at the southernmost reaches of its range.[11] The crab-eating fox has also been sighted in Panama since the 1990s.[12]
Its habitat also includes wooded riverbanks such as riparian forest. In the rainy season, their range moves uphill, whilst in drier times they move to lower ground.[13] Their habitat covers all environments except rainforests, high mountains, and open grassy savannas. In some regions of their range, they are threatened with extirpation.
The crab-eating fox creates monogamic teams for hunting; groups of several monogamic pairs may form during the reproductive season. Population density estimates vary between one individual per 4 km2 in Venezuela to 0.0003 individuals/km2 in Argentinian wetlands.[8][14][15] Territorialism was noticed during the dry season; during rainy seasons, when there is more food, they pay less attention to territory.[13] Hideouts and dens often are found in bushes and in thick grass, and there are typically multiple entrance holes per den. Despite being capable of tunneling, they prefer to take over other animals' burrows. Several characteristic sounds are made by the crab-eating fox such as barking, whirring and howling, which occur often when pairs lose contact with one another.
The crab eating fox is nocturnal, with peaks of activity in the middle of the night and the early morning.[16]
The foxes reach sexual maturity within 9–10 months year. Adult females gives birth to one or two litters per year, depending on the climate and the availability of food.[15] The reproductive period most often begins in November or December, and again in July. The birth of offspring follows after an approximately 56-day gestation,[17] typically in January, February or sometimes March,[13] then again from September to October. If giving birth to one litter, they typically give birth in the early spring. The breeding pair is monogamous and raises the pups together, which are weaned at around three months old and become independent of their parents around 5–8 months old.[15]
The crab-eating fox searches for crabs on muddy floodplains 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, crustaceans, insects, lizards and carrion. Their diet is varied and has been found to differ by different researchers, suggesting opportunistic feeding and geographical variation. During the wet season, the diet contains more crabs and other crustaceans, while during the dry season it contains more insects.[8] The crab-eating fox contributes to the control of rodents and harmful insects.
The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) lists the fox as not threatened by extinction.[18] The IUCN lists the crab-eating fox as being of "Least Concern".[2] There are no precise estimates of the population size, but it is common within its range and the population is stable.[4]
It is considered a threat to livestock by farmers, which leads to illegal hunting in some countries. The primary threat to the fox is disease from unvaccinated dogs.[14]
The crab-eating fox has five recognized subspecies,[1] differing in sizes and coloring of fur.[19]
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{{cite book}}: CS1 maint: others (link) The crab-eating fox (Cerdocyon thous), also known as the forest fox, wood fox, bushdog (not to be confused with the bush dog) or maikong, is an extant species of medium-sized canid endemic to the central part of South America since at least the Pleistocene epoch. Like South American foxes, which are in the genus Lycalopex, it is not closely related to true foxes. Cerdocyon comes from the Greek words kerdo (meaning fox) and kyon (dog) referring to the dog- and fox-like characteristics of this animal.
