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Cerdocyon thous - Crab-eating fox

Skull Pictures:

Dorsal    Ventral  

Lateral   Dentary

Photos by Christopher Yahnke, collection of the Field Museum of Natural History

Physical Description:

The coat of the Crab-eating fox varies across its body.  The back and sides are mixed with brown and gray which gives a yellowish tint (Nowak 1999).  The underside of its coat is brownish white (Nowak 1999).  The face, ears, and fronts of the legs are orange to brown or light brown in color, while the tips of the ears and backs of the legs are black (Berta 1982).  The ears are short and the tail is long and bushy and is dark pigmented or just the tip is black (Nowak 1999).  Adults weigh from six to seven kilograms, and they can range from 900 to 1000 mm in length from the head to the tip of the tail (Nowak 1999).


The Crab-eating fox ranges from northern South America in Colombia and Venezuela, along the eastern part of the continent, and south into Paraguay, Brazil, Uruguay, and Northern Argentina (Berta 1982).  They inhabit regions of savannah and woodland areas (Berta 1982).  Specific to Paraguay, the subspecies Cerdocyon thous entrerianus is the only Crab-eating fox found in Paraguay of the 5 subspecies of Crab-eating foxes (Berta 1982).

Ontogeny and Reproduction:

All information found on the reproduction of the Crab-eating fox has been done in captivity (Berta 1982).  Gestation in the Crab-eating fox ranges from 52 to 59 days (Berta 1982).  They have two litters a year at about 8 month intervals, and their litter size varies from 3 to 6 pups (Nowak 1999).  At birth the eyes and ears are closed and they have no teeth (Berta 1982).  Their eyes open about 14 days after birth (Nowak 1999).  Their weight ranges from 120 to 160 grams (Berta 1982).  Their coat color begins as charcoal gray then by day 20 after birth it begins to change until they achieve their adult coat at about day 35 (Berta 1982).
After the young are born, they enter three stages of development: early nesting stage, mixed nutritional dependency stage, and post weaning dependency stage (Berta 1982).  The early nesting stage begins on day one of birth and lasts until day 30, and it is where the young depend on the mother’s milk for nutrition (Berta 1982).  The mixed nutritional dependency stage lasts from days 30 to 90, and in this time the young become completely weaned (Berta 1982).  The final stage, post weaning dependency stage, lasts from 90 days to 5 months, and this is where the young’s nutrition comes mostly from solid food (Berta 1982).  The young become sexually mature within their first year of life at about 9 months (Nowak 1999).

Ecology and Behavior:

Even though the fur of the Crab-eating fox is not valuable, the fox is hunted constantly (Berta 1982).  The Crab-eating fox is nocturnal and hunts alone but may travel in pairs (Berta 1982).  Changes in their hunting area are related to the distribution and availability of prey in the wet and dry seasons which cause a shift in their diet as the seasons pass (Berta 1982).  The Crab-eating fox is omnivorous and helps control populations of small mammals, insects, and crabs by incorporating them into its diet (Nowak 1999).  Along with small mammals, insects, and crabs, the Crab-eating fox has been found to eat fish and birds according to an analysis of their scats (Farrell, Roman, & Sunquist 2000).

Literature Cited:

Berta, A.  1982.  Cerdocyon thous.  Mammalian Species, No: 186: 1-4.

Farrell, Laura E., Joseph Roman, Melvin E. Sunquist.  2000.  Dietary separation of sympatric carnivores identified by molecular analysis of scats.  Molecular Ecology  9(10): 1583.

Nowak, R.  1999.  Walker’s Mammals of the World, Sixth Edition.  Baltimore and London: John Hopkins University Press.


Reference written by Katherine Olejnichak Biol 378 (Mammalogy), University of WisconsinStevens Point:  Edited by Kim Moore. Page last updated 12-14-04.
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