The Brazilian guinea pig lives in small groups, usually consisting of a single male and one or two females. While each group occupies a separate nest concealed amongst brush and vegetation (3) (4), they share a complex network of tunnels and runs—constructed through the dense undergrowth—with the numerous groups that live close by (2). The Brazilian guinea pig primarily grazes on grass, but will also take leaves, seeds, flowers and bark (4). Being highly vulnerable to predators, this species feeds at dusk and dawn, never more than a few metres from cover, and with the group continuously on the alert for potential threats (2) (5). Predators mainly comprise birds of prey and South American mustelids, such as the greater and lesser grison (5). Although the Brazilian guinea pig breeds throughout the year, most births usually occur between September and April. Females can produce up to five litters in a single year, generally producing an average of two pups per litter after a gestation period of around 62 days (1). The young are born extremely well-developed, and on the first day are able to run and eat solid food, although they normally suckle for three weeks (2). Brazilian guinea pigs become sexually mature after just 30 days (2), and may live for around 8 years in captivity (3).

The Brazilian guinea pig closely resembles the well-known domestic guinea pig (Cavia porcellus), and is possibly its wild ancestor (2) (3). Like its domestic counterpart, the Brazilian guinea pig is a small rodent, with a stocky, tailless body, and a large head ending in a blunt snout (3) (4). The legs are short, while the feet are bare, with four toes on the front feet, and three on the rear, each equipped with strong claws (4) (5). Unlike the diverse coat patterns, lengths and colours found in the different breeds of domestic guinea pig, all Brazilian guinea pigs have long, coarse, dark grey-brown or black fur (4).

This species occurs in Colombia, Ecuador, Venezuela, Guyana, Brazil, Bolivia, north Argentina, Uruguay, and Paraguay (Dunnum, 2003; Woods and Kilpatrick, 2005). There are no records from French Guiana (Voss et al., 2001). It is found from 400 to around 3,000 m asl (Alberico et al. 2000, J. Vargas pers. comm.). The presence of this species needs to be confirmed in lowland Peru (J. Dunnum, pers comm.).

Brazilian guinea pigs occur in the neotropical region, but do not occur in tropical rain forests. They are native to Argentina, Bolivia, Brazil, Colombia, Ecuador, Guyana, Paraguay, Peru, Suriname, Uruguay and Venezuela (Dittmar, 2002; Dunnum et al., 2008).

Biogeographic Regions: neotropical (Native )

The northern part of the Brazilian guinea pig's large range extends from western Colombia eastwards to Venezuela, Guyana, Suriname, and the northern regions of Brazil bordering these countries. Since this species is absent from rainforest, the southern part of its range begins south of the Amazon basin, extending from Bolivia and southern Brazil, southwards through eastern Paraguay as far as Uruguay and north-east Argentina. Small populations also occur in extreme northern Peru and Ecuador (1).

Brazilian guinea pigs are medium-sized, herbivorous rodents. They are one of fifteen species of wild guinea pig in the subfamily Caviinae (Asher et al., 2004). They range in mass from 520 to 795 g, with an average mass of 637 g. They have stout bodies and a significantly reduced tail. Brazilian guinea pigs have four toes on their forefeet, while their hind feet have only three toes. Although males tend to be larger than females, brazilian guinea pigs have an average total body length of 274 mm, but range in size from 196 to 320 mm. Like most rodents, they lack canine teeth and have a dental formula of 1/1, 0/0, 1/1, 3/3. They have ever-growing teeth that are maintained at a constant length by continuous gnawing. Typically, they have brown pelage, but red and black variations also occur. Their coat is darkest along the spinal ridge and becomes increasingly light as it approaches the ventral surface of the animal.

Range mass: 520 to 795 g.

Average mass: 637 g.

Range length: 196 to 320 mm.

Average length: 274 mm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

Habitat and Ecology

Systems

• Terrestrial

Brazilian guinea pigs are primarily found in scrub grasslands and savannas, but also occur in the highlands of the Andes mountain range. They prefer areas of thick ground cover but can be found in disturbed habitats as well. They do not occur in tropical rain forests (Dunnum et al., 2008). Wild guinea pigs live in small groups consisting of 1 male, 1 to 2 females, and their young. They do not burrow, but instead rely on a series of tunnels and pathways constructed in dense ground vegetation (Asher et al., 2004).

Range elevation: 400 to 3,000 m.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: savanna or grassland

The Brazilian guinea pig is mainly found in shrubby grassland savanna and other open habitats, at elevations from 400 to 3,000 metres above sea level (1) (4)

Brazilian guinea pigs are generalist grazers and are strictly herbivorous. They primarily feed on true grasses (Poaceae, formally known as Gramineae), but will forage on many other kinds of grasses as well (Asher et al., 2004). They indiscriminately feed on seeds, leaves, stems, and in some cases, roots or tubers (Kraus et al., 2005).

Plant Foods: leaves; roots and tubers; seeds, grains, and nuts

Primary Diet: herbivore (Folivore , Granivore )

Brazilian guinea pigs are a major food source to many medium- to large-sized carnivores. Along with other herbivorous rodents, they help maintain grasslands by filling niches that are similar to those of grazing ungulates in Africa (Eisenberg, 1989). Also, they create a network of tunnels throughout the dense ground vegetation that are used by various species of small animals (Asher et al., 2004). Finally, Brazilian guinea pigs are hosts for various forms of parasites, including fleas (Tiamastus cavicola, Leptopsylla segnis, and Tiamastus cavicola), lice (Gliricola porcelli, Hoplopleura alata, and Polyplax spinulosa), mites (Myobia musculi and Eutrombicula bryanti), nematodes (Capillaria hepatica, Graphidioides mazzai, Trichuris gracilis, and Paraspirudera uncinata), and one species of trematode (Fasciola hepatica).

Ecosystem Impact: disperses seeds; creates habitat

Commensal/Parasitic Species:

• Leptopsylla segnis
• Tiamastus cavicola
• Gliricola porcelli
• Hoplopleura alata
• Polyplax spinulosa
• Myobia musculi
• Eutrombicula bryanti
• Capillaria hepatica
• Graphidioides mazzai
• Trichuris gracilis
• Paraspirudera uncinata
• Fasciola hepatica
• Tiamastus cavicola

Brazilian guinea pigs are medium-sized rodents that are important prey for cats, dogs, opossums, grison, raptors, snakes, and lizards. However, because of their size, smaller predators only prey upon juveniles (Scheibler, 2004). They typically forage in dense vegetation, near protective cover. They often forage in groups, which limits the per-capita amount of time spent scanning for predators, thus increasing the per-capita time spent foraging. When potential predators are detected, they alert their group mates by way of a high pitched scream (Cassini, 1991; Rood, 1972).

Known Predators:

• lesser grison (Galictis cuja)
• greater grison (Galictis vittata)
• jaguarundi (Puma yagouaroundi)
• ocelot (Leopardus pardalis)
• common cat (domestic and feral) (Felis catus)
• crab-eating fox (Cerdocyon thous)
• common dog (both domestic and feral) (Canis lupus familiaris)
• lutrine opossum (Lutreolina crassicaudata)
• crested caracara (Polyboras plancus)
• white-tailed kite (Elanus leucurus)
• roadside hawk (Buteo magnirostris)
• grey hawk (Asturina nitida)
• gray-headed kite (Leptodon cayanensis)
• Aplomado falcon (Falco femoralis)
• American kestrel (Falco sparverius)
• yellow-headed caracara (Milvago chimachima)
• burrowing owl (Speotyto cunicularia)
• crossed pit viper (Bothrops alternatus)
• Jararaca pit viper (Bothrops jararaca)
• South American rattlesnake (Crotalus basiliscus)
• boa constrictor (Boa constrictor)
• anaconda (Eunectes murinus)
• common black and white tegu (Tupinambis teguixin)

Anti-predator Adaptations: cryptic

Brazilian guinea pigs have two distinct scent glands, the dorsally located sebaceous gland and the perineal gland, located near the anus. Though males generally scent mark more frequently than females, both sexes scent mark with their perineal gland when their local environment has been disturbed. Scent marking is used to demarcate an individual's territory, to ward off rival males, and to attract potential mates (Beruter et al., 1974). Brazilian guinea pigs also communicate through a series of high pitched squeals and screams, which are used as warnings to other conspecifics when potential threats are detected (Eisenberg, 1989).

Communication Channels: visual ; acoustic ; chemical

Other Communication Modes: scent marks

Perception Channels: visual ; acoustic

Although Brazilian guinea pigs can survive for up to 8 years in the wild, due high predation rates on juveniles, their average lifespan is only 3 years (Eisenberg, 1989). Captive guinea pigs can live for up to 10 years.

Typical lifespan

Status: wild: 8 (high) years.

Average lifespan

Status: wild: 3 years.

Typical lifespan

Status: captivity: 10 (high) years.

Maximum longevity: 6 years (captivity) Observations: These animals have been reported to live up to 6 years in captivity (Richard Weigl 2005).

Brazilian guinea pigs are polygynous, with a single male mating with multiple females (usually no more than 2; Dunnam et al., 2008). On average, males are 11% larger than females and are very aggressive towards other males. While males defend their mates from potential rivals, they do not defend territorial boundaries, as resources are widely abundant. Although mating season peaks in early spring, females may have up to 4 litters throughout the year (Asher et al., 2004).

Mating System: polygynous

Compared to most rodents, brazilian guinea pigs reproduce relatively slowly. They have an extended period of gestation (62 days) and on average, have 2 well-developed pups per litter (Dunnum et al., 2008; Kraus et al., 2005). Pups are born "open-eyed" and "fully furred", and are able to move on their own hours after birth. They can eat solid food at 3 days old and are weaned by 25 days old. Brazilian guinea pigs can reproduce as early as 28 days old (Kraus et al., 2005).

Breeding interval: Wild guinea pigs breed up to 4 times per year

Breeding season: September through April

Range number of offspring: 1 to 5.

Average number of offspring: 2.

Range gestation period: 53 to 77 days.

Average gestation period: 62 days.

Range birth mass: 54 to 76 g.

Average birth mass: 63 g.

Range weaning age: 21 to 29 days.

Average time to independence: 32 days.

Range age at sexual or reproductive maturity (female): 19 to 48 days.

Average age at sexual or reproductive maturity (female): 29.5 days.

Range age at sexual or reproductive maturity (male): 18 to 46 days.

Average age at sexual or reproductive maturity (male): 28 days.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous ; post-partum estrous

Brazilian guinea pig females dedicate anywhere from 25 to 35 days to each litter; however, juveniles are capable of taking care of themselves as early as 5 days after birth (Eisenberg, 1989). Although nursing lasts for up to 25 days, pups can eat solid food as early as 3 days after birth. Juveniles disperse shortly after reaching sexual maturity at around 35 days old. Males invest little in the survival of their offspring, but protect females and pups for a short period after birth (Eisenberg, 1989; Asher et al., 2004).

Parental Investment: precocial ; female parental care ; pre-weaning/fledging (Provisioning: Female, Protecting: Male, Female); pre-independence (Protecting: Male, Female)

Brazilian guinea pig populations are generally stable, showing only slight declines due to human activity (Dittmar, 2002). The IUCN has classified them as a species of "least concern". They are broadly distributed, are tolerant to environmental disturbances, and have large populations throughout northern and central South America.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Classified as Least Concern (LC) on the IUCN Red List (1).

Population

Population Trend

Major Threats

There are currently no significant threats to the Brazilian guinea pig's survival. Although habitat degradation and loss is ongoing in many parts of its range, this species is believed to be capable of tolerating a degree of habitat modification and is currently widespread and common (1).

Conservation Actions

There are no specific conservation measures in place for the Brazilian guinea pig. It is, however, found in a number of protected areas throughout its range (1).

Brazilian guinea pigs are sometimes kept as exotic pets or used as a source of protein. As a result, they may potentially be vectors of zoonotic diseases to humans. Diseases commonly associated with Brazilian guinea pigs are cryptosporidiosis, inclusion body conjunctivitis, and salmonellosis (Comparative Medicine Program - MU College of Veterinary Medicine, 2002). Guinea pigs can be hosts to various forms of parasites (fleas, lice, mites, nematodes, and trematodes), and their dander, fur, urine, and saliva are common human allergens (Zacharisen et al., 2005, Dunnum et al., 2008).

Negative Impacts: injures humans (causes disease in humans , carries human disease); causes or carries domestic animal disease

Brazilian guinea pigs are believed to be the parent species of domesticated guinea pigs (Cavia porcellus).  Guinea pigs were domesticated as pets around 3000 years ago and are a common source of protein in some Andean cultures (Dittmar, 2002). Additionally, domesticated guinea pigs are commonly used as test subjects in biomedical research (Asher et al., 2004).