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Lycalopex gymnocercuspampas fox

By Travis Cooper

Geographic Range

Lycalopex gymnocercus, pampas foxes, are found in Paraguay, Uruguay, southern Brazil, eastern Bolivia and north of Rio Negro in Argentina. (Wilson and Reeder, 1993)

Habitat

These foxes are found in the pampas grasslands, hills, heath, ridges and deserts. They prefer plains and fields with tall grass, sierras, and small narrow wood areas along streams and occasionally forest areas. (Brooks, 1992)

Physical Description

Lycalopex gymnocercus is a medium-sized fox which has a brindled grey back with paler grey underparts. The head, neck and large ears are reddish, as are the outsides of the legs. The muzzle is black as far as the corners of the mouth, a feature that distinguishes them from the similar culpeo fox (Lycalopex culpaeus). Like other species in the genus, the long, bushy tail of L. gymnocercus has two black spots: one on the upper side at the base and another at the tip. These animals weigh between 4.2 and 6.5 kg, and average 62 cm in length. The tail length for Pampas Foxes averages about 34 cm. Males are approximately 10% heavier than females. Those animals in the northern part of their range are more vividly colored. (Boccaceci, 1998)

  • Sexual Dimorphism
  • male larger
  • Range mass
    4.2 to 6.5 kg
    9.25 to 14.32 lb
  • Average length
    62 cm
    24.41 in

Development

See Reproduction.

Reproduction

This species is monogamous. It is not known whether these foxes retain the same mate in subsequent breeding seasons, as they are solitary outside of the breeding season.

Pampas foxes are usually solitary, but are seen in pairs during the mating season. Breeding is monogamous and occurs from July through October. Both parents care for the young. Gestation lasts from 55-60 days. Females bear three to five pups in a den among rocks, under bases of trees or in burrows made by other animals. Young are born almost black but gradually lighten as they grow. At two to three months, the young begin to hunt with their parents. Age at maturity is unknown. The male pampas fox brings food to the female and her pups, who stay within the den until the pups are about three months old. At this time, the pups begin to hunt with their parents. (Alderton, Sept. 10, 2001)

  • Breeding interval
    Breeding occurs once yearly.
  • Breeding season
    Mating occurs between July and October.
  • Range number of offspring
    1 to 5
  • Average number of offspring
    2.5
  • Range gestation period
    55 to 60 days

Females nurse the pups in the den. The male will provide food for the altricial pups and females at the den. Young stay at the den for the first three months, after which they hunt with parents. (Alderton, Sept. 10, 2001)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • male
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female

Lifespan/Longevity

Pampas foxes live about 13.6 years in captivity. (Grambo, 1995)

  • Average lifespan
    Status: captivity
    13.6 years

Behavior

Pampas foxes have a relatively solitary lifestyle, except during the breeding season and when caring for their young. They exhibit two particularly interesting behaviors. They are known to collect objects which apprear mostly useless to them, such as bits of cloth and leather, which are often found in their dens. They also appear to play dead when approached by humans. If they are startled, these foxes will throw themselves to the ground, rigid, with their eyes closed, and remain in this position until the perceived threat passes. Although primarily nocturnal, they may be active during day in areas with low human populations. (Boccaceci, 1998)

Communication and Perception

Food Habits

Lycalopex gymnocercus is omnivorous, but primarily eats meat. Approximately 75% of the diet is comprised of equal percentages of rodents, lagomorphs (rabbits, hares, and pikas), and birds. These foxes are known to eat frogs and lizards. Fruits and other vegetable matter, like sugar cane stalks, are sometimes consumed. Near human dwellings they are said to take domestic poultry. (Berta, 1988)

  • Animal Foods
  • birds
  • mammals
  • amphibians
  • reptiles
  • Plant Foods
  • fruit

Predation

Information on predation is not available. Humans frequently hunt these foxes, thinking that they destroy livestock. The pampas fox may fall prey to eagles or larger carnivores. Lycalopex gymnocercus individuals remain motionless when humans make an appearance, and may continue to remain motionless if physically molested. This may be an antipredator behavior in which the fox tries to avoid being eaten by pretending not to be there at all. (Grambo, 1995; Nowak, 1999)

Ecosystem Roles

The decline in L. gymnocercus populations has had an adverse affect on agriculture in parts of their range due to increases in rodents and other crop pests. It can reasonably be inferred from this that fox predation plays an important role in regulating the populations of prey animals. (Boccaceci, 1998)

Economic Importance for Humans: Positive

These foxes are hunted and trapped for fur in several countries, including Uruguay, Paraguay, and Argentina. They are captured most often with leg-hold traps, but also caught using bowls, box traps, and dogs. Because these foxes keep agricultural pest populations in check, they have a positive impact on agriculture. (Grambo, 1995; Grambo, 1995)

  • Positive Impacts
  • body parts are source of valuable material
  • controls pest population

Economic Importance for Humans: Negative

Sometimes these foxes kill young sheep or take domestic poultry. (Alderton, Sept. 10, 2001)

  • Negative Impacts
  • household pest

Conservation Status

In Brazil, where the species enjoys complete protection, there is no market for fur. Pampas foxes are protected in Paraguay and Uruguay, but controlled hunting continues in these two countries. (Boccaceci, 1998)

Other Comments

These foxes were previously recognized in the genera Pseudalopex and Dusicyon. (Alderton, Sept. 10, 2001; Berta, 1988)

Contributors

Travis Cooper (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor), University of Wisconsin-Stevens Point.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Alderton, D. Sept. 10, 2001. "Azara's Zorro (*Dusicyon gymnocerus*)" (On-line). Accessed October 20, 2001 at http://www.lioncrusher.com/animal.asp?animal=4.

Berta, A. 1988. Quaternary evolution and biogeography of the large South American Canidae. Mammalia: Carnivora, 132: 1-149.

Boccaceci, M. 1998. "Azara's zorro (Pseudalopex gymnocercus)" (On-line). Accessed October 20, 2001 at http://www.canids.org/SPPACCTS/dgymnocer.htm.

Brooks, D. 1992. Notes on Group Size, Density, and Habitat Association of the Pampas Fox in the Paraguayan Chaco. Mammalia, 56: 314-316.

Grambo, R. 1995. The World of the Fox. Vancouver, British Columbia: Greystone Books.

Nowak, R. 1999. Walker's Mammals of the World, Sixth edition. Baltimore and London: The Johns Hopkins University Press.

Wilson, D., D. Reeder. 1993. Mammal Species of the World. Washington, DC: Smithsonian Institution Press.

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