Cavia aperea
Brazilian guinea pig

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). (Dittmar, 2002; Dunnum, et al., 2008)

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). (Asher, et al., 2004; Dunnum, et al., 2008)

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. (Asher, et al., 2004; Eisenberg, 1989; Asher, et al., 2004; Eisenberg, 1989)

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). (Asher, et al., 2004; Dunnum, et al., 2008)

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). (Dunnum, et al., 2008; Kraus, et al., 2005)

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). (Asher, et al., 2004; Eisenberg, 1989; Asher, et al., 2004; Eisenberg, 1989)

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. (Asher, et al., 2004; Eisenberg, 1989)

Brazilian guinea pigs are social animals that live in small familial groups consisting of 1 male, 1 to 2 females, and their offspring (Asher et al., 2004; Rood, 1972). Familial groups often occur in clusters, with dozens of groups located in adjacent territories. They communicate through auditory signals and scent marks. Males scent mark using a gland above their anus. Although they are unlikely to scent mark specific territories, they often mark their mates and defend them against rival males (Asher et al., 2004; Beruter, Beauchamp, and Muetterties, 1974). (Asher, et al., 2004; Beruter, et al., 1974; Cassini, 1991; Rood, 1972)

Brazilian guinea pigs are both diurnal and crepuscular, venturing out into the grasslands for short periods of time to graze, then seeking cover in dense shrubs. They often graze in small groups to increase predator detection and maximize their per-capita grazing time (Cassini, 1991). (Asher, et al., 2004; Beruter, et al., 1974; Cassini, 1991; Rood, 1972)

Home ranges of Brazilian guinea pigs are between 500 and 1000 m^2, depending on resource availability. Males' home ranges are up to twice as large as those of females and usually overlap with their mates' home ranges. Optimal habitats are located near lakes or rivers and include areas with dense shrub for cover, and grass for foraging (Asher et al., 2004; Rood, 1972). (Asher, et al., 2004; Eisenberg, 1989; Rood, 1972)

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). (Beruter, et al., 1974; Eisenberg, 1989)

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). (Asher, et al., 2004; Kraus, et al., 2005)

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). (Asher, et al., 2004; Cassini, 1991; Rood, 1972; Scheibler, 2004)

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). (Dunnum, et al., 2008; Eisenberg, 1989)

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). (Asher, et al., 2004; Dittmar, 2002)

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). ("Guinea Pig Diseases", 2002; Dunnum, et al., 2008; Zacharisen, et al., 2005)

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. (Dittmar, 2002; Dunnum, et al., 2008)