Viscachas and chinchillas

(Chinchillidae)

Class Mammalia

Order Rodentia

Suborder Hystricognathi

Family Chinchillidae

Thumbnail description
Rabbit-sized, stout bodied, large hind limbs for leaping, dense and soft fur, large head, dorsal pelage ranging from gray to black

Size
Head and body 11.8–23.6 in (300–600 mm); tail 2.9–10.5 in (75–267 mm); weight 1.1–19.8 lb (0.5–9 kg)

Number of genera, species
3 genera; 6 species

Habitat
Andean, barren, steppe, pampas, rocky outcrops, scrub, and grasslands

Conservation status
Critically Endangered: 1 species; Vulnerable: 1 species; Lower Risk/Near Threatened: 1 species; Data Deficient: 1 species

Distribution
Southern cone of South America, primarily in southern Peru, Bolivia, Argentina, extending from northern Chile to the Andean foothills in Patagonia

Evolution and systematics

Representative lineages of the family Chinchillidae extend from the Oligocene to the Recent in South America. Members of this family are placed in the superfamily Chinchilloidea. Determination of the closest relative of chinchilloids has been difficult. Based on postcranial features and musculature, it has been suggested that chinchilloids shared a common ancestry with the New World porcupine superfamily Erethizontoidea. On the other hand, recent molecular phylogenetic studies are indicative of a strong relationship between the families Chinchillidae and Dinomyidae. Within the family, the Andean genera Lagidium and Chinchilla appear most closely related with Lagostomus being the most divergent lineage. Some taxonomic controversy persists over the recognition of Chinchilla lanigera as a distinct species from C. brevicaudata.

Physical characteristics

All species are large-bodied rodents with large, broad heads, thick fur, and rabbit-like in appearance. Chinchillas have extremely large auditory bullae relative to the other genera. The plains viscacha, Lagostomus maximus, is the largest species, weighing up to 20 lb (9 kg). Compared to the mountain viscacha, Lagidium viscacia, which weighs up to 6.6 lb (3 kg), chinchillas are much smaller, weighing less than 2.2 lb (1 kg). All species have strong hind legs and feet. Mountain viscachas and chinchillas are adapted for leaping, whereas the plains viscacha is more adapted to burrowing. Except for the plains viscacha, most species have minimal digit reduction. Chinchillas and mountain viscachas have longer tails relative to the head and body length. All species have soft underfur, and pelage color is generally darker on top and lighter on the ventral side. The plains viscacha varies in dorsal pelage color in response to differences in substrate coloration, and chinchillas have bluish dorsal coloration with lighter underside.

Distribution

Both mountain viscachas and chinchillas occur in Andean regions, distributed from Peru to Patagonia, while the plains viscacha occurs at lower elevations in portions of southern Paraguay and northern Argentina.

Habitat

All species live in burrows or rocky crevices. Elevations of preferred habitats vary from below 1,640 ft (500 m) for the plains viscacha to 13,120–16,400 ft (4,000–5,000 m) for chinchillas and mountain viscachas. The plains viscacha occurs in steppe or grassland regions characterized by barren vegetation near the burrow system. Species of the other genera reside in rocky areas with sparsely distributed vegetation.

Behavior

Plains viscachas excavate complex burrow systems with their front feet that can be occupied for up to 70 years. Burrow systems of the plains viscacha are colloquially known as a "viscacheras," a term used to describe the characteristic piles of debris collected and placed at the burrow's entrance. Both the mountain viscacha and chinchilla are equipped for leaping and generally live in crevices under rocky outcrops. Like chinchillas, plains viscachas are nocturnal, whereas the mountain viscacha is active during the day. All species of chinchillids are colonial, yet vary in the

degree of social structure. According to some accounts, colonies of the plains viscacha are restricted to a communal burrow system and consist of a dominant male and other member of the family group. Colony size range is 15–30 individuals. Both chinchillas and mountain viscachas live in smaller family groups, with a more dispersed colonial structure of individual groups within an area. These large, more sparsely distributed colonies range in size from as few as four up to 100 individuals. Plains viscachas have a broad repertoire of vocalizations consisting of high-pitched whines, alarm calls, and the characteristic "uh-huh" sound. The mountain viscacha's warning call consists of a tweeter or high-pitched whistle.

Feeding ecology and diet

All species are herbivorous, feeding on grass and seeds. Both the mountain viscacha and the chinchilla eat while sitting erect. The plains viscacha forages at dusk and during the night. The intensity of grazing by the plains viscacha has been observed to result in open patches where forbs become the

dominant vegetation. If colonies are removed from these regions, grasses displace forbs as the dominant vegetative cover. Mountain viscachas feed on vegetation such as lichens, mosses, and grasses that occur at high altitudes.

Reproductive biology

All chinchillids have long gestation periods ranging from 90 to 154 days. Average at sexual maturity for females is eight to 15 months. Young are born precocial, and one to three litters are produced each year with size of litters ranging from one to six.

Conservation status

Overharvesting by humans has impacted all species of chinchillids. Chinchilla lanigera is listed as Vulnerable by the IUCN, and C. brevicaudata as Critically Endangered. Lagidium wolffsohni is considered common in southwest Argentina and Chile, data on L. viscacia are deficient, and the status of L. peruanum is unknown. According to 1999 reports, the plains viscacha is considered a pest and has declined throughout its range as a result of eradication programs.

Significance to humans

Both species of chinchilla were commercially harvested in Chile, with over 500,000 pelts exported between 1900 and 1909. The plains viscachas compete with domestic livestock, and this species has also been intensely harvested, with over 370,000 skins exported over a three year period in the 1970s. Mountain viscachas also are prized for their meat and fur.

Species accounts

List of Species

Plains viscacha

Lagostomus maximus

taxonomy

Lagostomus maximus (Desmarest, 1817), type locality unknown; possibly from pampas of Buenos Aires, Argentina.

other common names

English: Vizcacha; French: Viscache, lièvre des pampas.

physical characteristics

Large rodents with head and body length averaging over 19.7 in (500 mm). Tail length averages 6.9 in (175 mm) and total weight up to 19.8 lb (9 kg). Males tend to be larger than females by approximately 15% in body length and 30% in body weight. Individuals have large, broad heads, and males have a distinctive black mustache and stiff whiskers. Broad black and white stripes on face. Underparts are white and dorsal pelage ranges from gray to brown, depending upon soil color. The tail has stiff hairs, is bare ventrally, and provides support for sitting upright. Digits reduced to three on the hind foot.

distribution

Occurs in southern Paraguay, southeastern Bolivia, and Argentina.

habitat

Prefers grassland and steppe habitats at elevations below 9,840 ft (3,000 m). Areas around burrow systems are sparsely vegetated with piles of debris around openings located under bushes.

behavior

Construct elaborate burrows that house successive colonies for decades. Single males defend burrow systems and are the dominant breeders. Variety of vocalizations and gestures are used during aggressive interactions among individuals. Members of colonies produce alarm calls and perform allogrooming.

feeding ecology and diet

Feed at night on grasses and seeds. Heavy grazing alters the abundance and diversity of grass species. They are ecologically similar to North American prairie dogs. Almost 94% of diet is grass, resulting in severe grass cover depletion. Cattle and plains viscachas share the same diet.

reproductive biology

Polygamous. Gestation 152 days, seasonal breeder with one litter per year in southern portion of range, no more than two litters per year in other ranges. Litter size is two.

conservation status

Not listed by the IUNC though extinction of local colonies as a result of eradication programs is common.

significance to humans

Considered a competitor with domestic species of livestock. Burrow system presents a potential threat to horses and cattle. Harvested for food and fur. In the past, pelts were exported.

Mountain viscacha

Lagidium peruanum

taxonomy

Lagidium peruanum (Meyen, 1833) Pisacoma, Puno Department, Peru.

other common names

English: Peruvian mountain viscacha, common mountain viscacha; French: Viscache du Pérou.

physical characteristics

Weight averages 2.9 lb (1.3 kg), head and body length 14.8 in (375 mm), and tail 10.5 in (267 mm). Rabbit-sized with powerful legs and long tail. Fur is thick and soft, dorsal pelage is gray to orange with lighter ventral region. Tip of tail is dark, ears long, and four digits on front and hind feet.

distribution

Andes mountains in Peru at elevations ranging between 9,840 and 16,400 ft (3,000–5,000 m).

habitat

Prefers dry, rocky, habitats between the timber line and snow line of the Andes mountains with sparse vegetation and coarse grasses. Often found near water that offers better vegetation than the drier regions within their habitat. Seeks shelter in rocky crevices.

behavior

Diurnal species that is active throughout the year. Leaps among rocks and performs a series of whistles and trills associated with warning. Colonial structure composed of small family units of two to five individuals in a subdivided colony that can be as large as 75 animals.

feeding ecology and diet

Herbivorous, feeds on grasses, lichens, and mosses occurring at high elevations.

reproductive biology

Males tend to be promiscuous. Gestation is 140 days, litter size of one precocial offspring.

conservation status

Not listed by the IUCN.

significance to humans

Harvested by humans for food and pelts.

Long-tailed chinchilla

Chinchilla lanigera

taxonomy

Chinchilla lanigera (Molina, 1782), Coquimbo, Coquimbo Province, Chile.

other common names

French: Chinchilla laniger.

physical characteristics

Average total length of 14.4 in (365 mm), tail length 5.6 in (141 mm), and weight 0.9 lb (0.4 kg). Appearance is rabbit-like with larger ears than C. brevicaudata and a longer brushy tail. Dorsal fur is gray and black. Tympanic bullae are inflated.

distribution

Mountainous regions of Chile.

habitat

Arid to semi-arid, montane regions between 9,840–16,400 ft (3,000–5,000 m). Prefers rocky habitats with sparse vegetation.

behavior

Either nocturnal or crepuscular, excellent leapers, and colonial. Colony size can be several hundred individuals organized into smaller subgroups. Highly vocal with females apparently dominant sex displaying higher levels of aggression.

feeding ecology and diet

Female chinchillas are mostly monogamous. Predominantly herbivorous feeding on grasses and seeds, yet will eat insects. Eats while sitting on hind legs and holding food with front paws.

reproductive biology

Produces two litters per year, and females experience postpartum estrus. Gestation averages 111 days, and litter size is two on average.

conservation status

Listed as Vulnerable with a high risk of extinction by IUCN. Chilean government lists both species as Endangered. According to a 1996 account, C. lanigera is almost extinct in the wild, with the last official citing in 1953. Commercial hunting resulted in the decimation of populations, with almost seven million pelts exported from Chile prior to protection.

significance to humans

Prized for pelts. Captive stocks are maintained for the fur industry, and these stocks are the result of cross breeding.

Resources

Books

Eisenberg, J. F. "The Function and Motivational Basis of Hystricomorph Vocalizations." In The Biology of Hystricomorph Rodents, edited by I. W. Rowlands and Barbara J. Weir. London: Academic Press, 1974.

Kleiman, D. G. "Patterns of Behaviour in Hystricomorph Rodents." In The Biology of Hystricomorph Rodents, edited by I. W. Rowlands and Barbara J. Weir. London: Academic Press, 1974.

Nowak, R. M. Walker's Mammals of the World. Vol. 2. Baltimore: Johns Hopkins University Press, 1991.

Redford, K. H., and J. F. Eisenberg. Mammals of the Neotropics: The Southern Cone. Vol. 2. Chicago: University of Chicago Press, 1992.

Rowland, I. W. "Mountain Viscacha." In The Biology of Hystricomorph Rodents, edited by I. W. Rowlands and Barbara J. Weir. London: Academic Press, 1974.

Weir, B. J. "The Tuco-Tuco and Plains Viscacha." In The Biology of Hystricomorph Rodents, edited by I. W. Rowlands and Barbara J. Weir. London: Academic Press, 1974.

Wilson, D. E., and D. M. Reeder. Mammal Species of The World. Washington, DC: Smithsonian Institution Press, 1993.

Woods, C. A., and J. W. Hermanson. "Myology of Hystricognath Rodents: An Analysis of Form, Function, and Phylogeny." In Evolutionary Relationships Among Rodents: A Multidisciplinary Analysis, edited by W. Patrick Luckett and Jean-Louis Hartenberger. New York: Plenum Press, 1985.

Periodicals

Adkins, R. M., E. L. Gelke, D. Rowe, and R. L. Honeycutt. "Molecular Phylogeny and Divergence Time Estimates for Major Rodent Groups: Evidence from Multiple Genes." Molecular Biology and Evolution 18 (2001): 777–791.

Branch, L. C., J. L. Hierro, and D. Villarreal. "Patterns of Plant Species Diversity Following Local Extinction of the Plains Vizcacha in Semi-arid Scrub." Journal of Arid Environments 41 (1999): 173–182.

Grand, T. I., and J. F. Eisenberg. "On the Affinities of the Dinomyidae." Saugetierkundliche Mitteilungen 30 (1982): 151–157.

Huchon, D., and E. J. P. Douzery. "From the Old World to the New World: A MolecularChronicle of the Phylogeny and Biogeography of Hystricognath Rodents." Molecular Phylogenetics and Evolution 20 (2001): 238–251.

Jiménez, J. E. "The Extirpation and Current Status of Wild Chinchillas C. lanigera and C. brevicaudata." Biological Conservation 77 (1996): 1–6.

Pereira, J. A., R. N. D. Quintana, and S. Monge. "Diets of Plains Vizcacha, Greater Rhea, and Cattle in Argentina. " Journal of Range Management 56 (2003): 13–20.

Puig, S., F. Videla, M. Cona, S. Monge, and V. Roig." Diet of the Mountain Vizcacha (Lagidium viscacia Molina, 1782) and Food Availability in Northern Patagonia, Argentina." Zeitschrift fur Saugetierkunde 63 (1998): 228–238.

Rodney L. Honeycutt, PhD