Microcavia australis

Geographic Range

Southern cavies, Microcavia austrialis , are found in Argentina, southern Chile, and southern Bolivia. In central Argentina the species is the most abundant of the Caviinae in semiarid thornbush habitats but the species is not found in the humid northeastern provinces. These animals are often found in the Monte and Patagonian deserts.

• Biogeographic Regions
• neotropical neotropical
  • native native

Habitat

Microcavia australis uses clumps of thornbush for cover, and may also use runways that it makes through the open areas. These animals dig shallow depressions under the thornbushes, which have been cleared of debris, and use these as a safe place to sleep or rest. Microcavia australis has also been found in burrows dug in the same area. The areas that this species utilizes for burrows are under bushes with a broad canopy that is low to the ground.

• Habitat Regions
• temperate temperate
• tropical tropical

• Terrestrial Biomes
• desert or dune desert or dune
• chaparral chaparral

Physical Description

Microcavia australis has a body that is short and robust with a head that makes up about 1/3 of the head-body length. Head-body length averages 22 cm, and no tail is present. Adults weigh about 300 g. Microcavia australis is a ground-dwelling hystricomorph rodent. Its coat is a course, dark agouti, from brown to a grayish-color. There is a prominent white ring around the eye. The species is known to have fairly large eyes and big ears, which are close to the head. The forefeet are strong and flat, usually with four digits, each ending with a sharp claw. The hind feet have three elongated digits with claws.

This animal uses pedal locomotion, which is when the animal walks on its soles and has its heels touching the ground. The hair sheds easily when these animals are handled. Incisors are short, and the cheek teeth are constantly growing.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Reproduction

Microcavia australis is polygynous. Males become very aggressive during reproduction in the wild. As a result, there is usually only one male in a group of females.

• Mating System
• polygynous polygynous

Microcavia australis males become very aggressive during mating in the wild. As a result there is usually only one male in a group of females. He will sometimes form a temporary association with the female and her young and follow her around, nose to rump, especially if the female is in estrus. However if any two breeding males come in to contact it almost always involves aggression. This can be especially evident when a female is close to giving birth. Males gather around her, and show aggression to one another. Immediately after the young are born, as many as six males may pursue the female.

In Argentina breeding takes place between August to April. Gestation lasts for between 50 and 75 days. Litters typically contain about three young.

The young of M. austrialis are precocious. They weigh about 30 grams at birth and are able to run and eat solid food during the first day of life. The average weaning time is about three weeks of age. Interestingly, the young will nurse from any female that is lactating at the time.

Females are polyesterous, and have a postpartum estrus immediately after giving birth. A female may be able to mate again within 15 days if fertilization does not occur. The females become reproductively mature at about 1 to 3 months of age.

The adults of both sexes tolerate young animals up to 1 month old. At this time, apparently the young are expelled from the group and become totally independent.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• viviparous viviparous
• post-partum estrous

The young of this species are precocious, and parental care does not last very long. Neonates have eyes open, can eat solid food, walk, and run, all from birth. The mother weens young at about 3 weeks. Young animals sometimes nurse from a female other than their own mother. Young become independant at about one month of age. Males do not contribute to parental care in this species.

• Parental Investment
• no parental involvement
• precocial precocial
• pre-fertilization
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • protecting
    • female

Lifespan/Longevity

Maximum life expectancy in the wild is about 3 to 4 years, and can be up to 8 years in captivity.

Behavior

Stability of social groups seems to vary between habitats. In the deserts, M. australis keep strict fidelity to a burrow system. In a less arid habitats, these animals show a loose social organization. Cavia and Microcavia never occur in the same area. And competition between Galea and Microcavia seems to be minimized by the utilization of different foraging tactics. Microcavia australis never stray more than 4 meters from cover. This species a diurnal herbivore.

Microcavia australis lives on the ground, and moves around with pedal locomotion. It excavates holes and burrows, usually under close cover of vegetation.

• Key Behaviors
• terricolous
• diurnal diurnal
• motile motile
• sedentary sedentary
• social social
• dominance hierarchies dominance hierarchies

Home Range

The home range sizes is on average about 3,200 square meters for one study while in another study male ranges overlapped sometimes and were slightly larger than the ranges of the females. Males having a range of 7,720 square meters and females 3525 square meters.

Communication and Perception

The vocalizations of M. australis include an alarm "tsit," a "twitter" when they are annoyed, and a "shriek" for fear. They also use olfactory cues during mating season. There is obvious tactile communication between rival males, as well as between males and females during mating. Although not reported, visual cues, such as body postures, are probably important in this diurnal species.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Microcavia australis is a diurnal herbivore. They prefer leaves and are active climbers.

• Primary Diet
• herbivore herbivore
  • folivore folivore

• Plant Foods
• leaves
• roots and tubers
• seeds, grains, and nuts

Predation

Microcavia australis is prey for South American weasels and large raptors. Microcavia australis never stray more than 4 meters from cover, which probably helps to reduce predation from raptors. The burrow system also helps prevent predation by raptors, but does little to deter weasels.

Ecosystem Roles

Microcavia australis helps maintain the plants that they utilize as shelter and a food source including, Argentinean thornbushes, Cochinus fasciculatus , Condalia microphylla , and Lycium gilliesianum .

In addition to effects on plant communities, this species may have impact on other mammal populations. Cavia and Microcavia never occur in the same area, possibly because of niche overlap. Competition between Galea and Microcavia seems to be minimized by the utilization of different foraging tactics.

Finally, this species provides an important part of local food webs. Raptors as well as South American weasals are reported to prey upon M. australis , although it is likely that they are taken by a much wider variety of predators.

Economic Importance for Humans: Positive

There are no data available allowing assessment of the impact of this species on human economies.

Economic Importance for Humans: Negative

The negative impact of this species on human economies has not been detailed in the literature.

Conservation Status

At this time the animal is not threatened, endangered or exploited. It is not listed by CITES or IUCN.

Additional Links

Encyclopedia of Life

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Kristina Chartier (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor, instructor), University of Wisconsin-Stevens Point.

References

Campos, C. 2001. Utilization of food resources by small and medium-sized mammals on the Monte desert biodome, Argentina. Austral-Ecology , 26 (2): 142-149.

Lacher, T., M. Cassini, D. MacDonald, S. Norris. 2001. Cavidae. Pp. 672-675 in The Encyclopedia of Mammals . Oxford: Adromedia Oxford Limited.

Nowak, R. 1997. "Walker's Mammals of the World Online" (On-line). Accessed October 24, 2002 at http://www.press.jhu.edu/books/walkers_mammals_of_the_world/rodentia/rodentia.caviidae.microcavia.html .

Rood, J. 1970. Ecology and social behavior of the Desert Cavy ( Microcavia australis ). American Midland Naturalist , 83/2: 415-454.

Tognelli-Marelo, F. 2001. Microcavia australis. Mammalian Species , 648: 1-4.