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Crab-eating Fox - Cerdocyon thous
Scalesofanubis Wrote:Crab-eating Fox - Cerdocyon thous

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Scientific classification
Species:Cerdocyon thous

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The crab-eating fox (Cerdocyon thous), 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 characteristics of this animal.

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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 pounds (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 kilograms (11 to 18 lb) (A. Hover; C Yahnke, 2003). It is mainly nocturnal and also is active at dusk, 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.

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Cerdocyonina is a tribe which appeared around 6.0 million years ago (Mya) in North America as Cerdocyon avius becoming extinct by around 1.4—1.3 Mya. living about 4.7 million years. This genus carried on in South America from an undetermined time, possibly around 3.1 Mya and continues to present in the form or similar to the crab-eating fox. Cerdocyon thous, C. avius and other species of the genus Cerdocyon underwent radiational evolution on the South American continent.
As one of the species of the tribe Canini, it is related to the Canis genus. The crab-eating fox's nearest relative, theorized at present, is the Short-eared Dog. This, however, has to be supported by mitochondrial investigations. 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).

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Range and Habitat
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 to Paraguay, Uruguay and Northern Argentina. (Eisenberg, 1999) The crab-eating fox has also been sighted in Panama since the 1990s.
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 extirpation.

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Crab-eating fox creates monogamic 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.
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, 199).
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, crabs and carrion. 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). The crab-eating fox contributes to the control of rodents and harmful insects.

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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 Concern".
This fox is occasionally hunted, but the pelt 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 dogs' 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.

Mauro20 Wrote:This is by far the most common wild canid around here. Some info on their feeding habits here. Tab for prey animals:

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Plants ingested:

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It's interesting to see that they ate some rather poisonous/venomous animals, like a pitviper (Bothrops) and toads from the genus/subgenus Chaunus, closely related to cane toads.

Table from another study (

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I'm not sure why it got these weird dark rectangles and lines here on the forum.
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[-] The following 1 user Likes Taipan's post:
  • Claudiu Constantin Nicolaescu
Stronger together: observation on crab-eating foxes (Cerdocyon thous) cooperatively oreying their potential predator.

We describe the first record of cooperative predation by two crab-eating foxes (Cerdocyon thous) 
upon an adult short-tailed boa (Boa constrictor amarali) at a Brazilian Cerrado spot. Although it is known that  C. thous forages in pairs or in small family groups, there has been no report of crab-eating foxes preying cooperatively on medium and large-sized preys until now. Our observation sheds light on a poorly-known aspect of  feeding behavior of C. thous that could not be recorded through scat analysis, which is currently main source of information on carnivores’ feeding ecology.

Our opportunistic observation of a pair of crab-eating foxes attacking and killing an adult short-tailed boa was made on September 2006. The interaction lasted about 20 minutes and happened at the end of the 
afternoon (ca.18:30 h), at an anthropized remnant of Cerrado, near MS-178 highway (20°58′ 10.85″ S /56°31′05.78″W), at the municipality of Bonito, Mato Grosso do Sul State, Brazil. The observation was filmed and photographed from a distance that did not influence the behavior of the animals. When first sighted, crab-eating foxes were already attacking the boa. Therefore, we do not know details on how the interaction started. However, it was possible to observe that the short-tailed boa was alive and actively trying to defend itself, curling up and striking 
back against the crab-eating foxes. No signs of 
crab-eating foxes’ den or litter were detected within 100 m of the site of interaction spot. No clues of defensive (parental) behavior (e.g., threaten and alert or siren calls) of the types reported for crab-eating foxes (Brady 1979, 1981; Lemos & Azevedo unpublished data) and other South American canids (Chatellenaz et al. 2018) were detected. This apparent lack of parental behavior reinforces the notion that 
this was a predatory, not defensive behavior.
During the whole observation crab-eating foxes acted jointly and cooperatively. Attacks consisted of alternate or simultaneous bites by 
the two crab-eating foxes to the short-tailed 
boa, followed by several jolts and strong pulls 
in opposite directions. The short-tailed boa 
constantly wrapped itself in order to protect its head, suggesting a defensive behavior. Joint 
attacks prevented an efective defense response 
by the boa, making it vulnerable against its 
attackers. After several bites, the boa started 
to show evident apathy and the crab-eating 
foxes signs of tiredness. Then the crab-eating 
foxes took turns on the attacking, while the 
other rested at the side. A lethal neck-bite 
killed the snake, which remained stretched, 
belly up, motionless on the ground. With the 
natural daylight gone, it was not possible to 
carry observations on the total ingestion of
the prey. However, after the death of the boa, 
the female crab-eating fox started growling at 
the male when the latter approached the snake, 
displaying a behavior that may indicate a sign 
of dominance and a sort of hierarchy during 
prey consumption.
Although C. thous is frequently observed 
foraging in pairs but not sharing resources 
most of the time (Brady 1979; Lemos & Facure 
2011), the two crab-eating foxes displayed 
elaborated sociality and an ability to kill a prey 
cooperatively. Similar cooperative behavior for 
subjugating larger prey has been reported for 
bush dogs, Speothos venaticus (Lund, 1842), 
a highly social canid that may live and hunt 
in groups of up to 12 individuals (Beisiegel 
& Ades 2002; Lima et al. 2012). Apparently, 
the uninterrupted attack to the boa, through 
several and alternating bites by both members of the pair, was an important strategy to 
successfully subjugate the snake, preventing 
effective defense.
Records of cooperative hunting on large preys 
for C. thous are virtually nonexistent to our 
knowledge, except for one single description 
by R. Rudran at Brady (1979), who reports an 
ambush of a tegu (Tupinambis sp.) by a pair of 
crab-eating foxes. At the occasion the canids 
displayed similar behaviors of alternating at repeatedly attacking the prey, followed by pulling 
it in opposite directions and, finally, growling to 
each other once the prey was killed. Our new 
record, combined with those of Brady (1979) 
and Chatellenaz & Guzmán (2015), suggests 
that the benefits of sharing food may occasionally drive species away from the general rule 
predicted for small canids (Moehlman 1989). 
Additionally, the observation indicates that crab-eating foxes may actually prey on snakes 
(Gonzalez et al. 2016), instead of only ingesting them through scavenging (Rocha et al. 
2004). Boas are not only a large prey but also 
a potential crab-eating fox predator (Almiron 
et al. 2011). Therefore, our record opens the 
possibility that pairs of crab-eating foxes may 
consume other large preys, including some 
found in scats that are generally considered 
as carcass intake.
Considering the lack of observational records 
on feeding behavior for South American canids, 
our report is an important contribution for the 
current knowledge on the feeding ecology and 
hunting strategy for this group. We recommend 
the development of natural history studies as-
sociating direct observation to other methods 
(e.g., Global Positional System monitoring) 
for better understanding social relationships 
and interspecific interactions that may shape 
behavioral habits of South American canids.

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[-] The following 2 users Like Shenzi's post:
  • Claudiu Constantin Nicolaescu, Mauro20

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