Cavia

Diversity

Guinea pigs, or cavies, (genus Cavia ) are in the subfamily Caviinae , which also includes mountain cavies ( Microcavia ) and yellow-toothed cavies ( Galea ). There are six widely recognized species of guinea pigs, one of which has been domesticated. The extant species include Brazilian guinea pigs ( Cavia aperea ), shiny guinea pigs ( Cavia fulgida ), Moleques do sul guinea pigs ( Cavia intermedia ), greater guinea pigs ( Cavia magna ), montane guinea pigs ( Cavia tschudii ), and domestic guinea pigs ( Cavia porcellus ). There is also fossil evidence of four extinct Cavia species. Guinea pig species vary in coloration, but they all have have short, stocky bodies with short legs. In some species, males are larger than females on average.

Geographic Range

Wild guinea pigs are endemic to South America. However, domestic guinea pigs ( Cavia porcellus ) are found worldwide as popular household pets or as laboratory research animals.

• Biogeographic Regions
• neotropical neotropical
  • native native

• Other Geographic Terms
• cosmopolitan cosmopolitan

Habitat

Guinea pigs typically live in areas with tall, dense vegetation that can conceal them from predators, although they also forage in open areas. Wild guinea pigs typically inhabit grasslands and scrublands at a wide range of elevations. They live in herds that occupy a shared home range, which varies in size depending on resource availability (e.g., food, shelter). In some cases, males have larger home ranges than females.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland

• Other Habitat Features
• urban urban
• agricultural agricultural

Systematic and Taxonomic History

Guinea pigs are rodents (order Rodentia ) in the family Caviidae , which includes guinea pigs and cavies (subfamily Caviinae ), maras (subfamily Dolichotinae ), and capybaras (subfamily Hydrochoerinae ). There is debate regarding the number of species that truly belong in the genus Cavia genus, but there is consensus on five wild species and one domestic species. The genus was first described in 1766 with one species, Cavia pallas , which is no longer considered a valid taxonomic species.

Physical Description

Guinea pigs have oblong, stocky bodies with no tails, short legs, and short, wide ears. They have four fingers on their forefeet and three fingers on their hindfeet, with short, sharp nails on all of their digits. Guinea pigs have variable hair length and coloration. They can be tan, brown, white, or black and can either be one solid color or have splotchy, multicolored pelage. There is a breed of domestic guinea pig ( Cavia porcellus ), called skinny pigs, that are nearly hairless, with tufts of hair on their muzzles and feet.

Guinea pigs are large compared to most other rodents, with adults ranging from 20 to 25 cm in length and 700 to 1,200 g in weight. Male and females look virtually identical, although males are slightly larger on average. Because male and female guinea pigs are similar in size and lack conspicuous external genitalia, it can be difficult to determine their sex, especially when they are juveniles. Guinea pigs have two prominent incisors, which grow continuously and they can be a medical concern if they grow too long.

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

• Sexual Dimorphism
• sexes alike
• male larger

Reproduction

Wild guinea pigs exhibit polygynous mating behavior, but they may also be monogamous within breeding seasons. Sexually mature males exhibit "nuzzling" behavior, which is characterized by sniffing and licking of sexually mature females. Males will follow females they are interested them while circling them and nuzzling them. Males may also emit low "purring" vocalizations, and eventually mount females if they are receptive to mating. Males will mark previous mates using chemicals from their anal glands, but they rarely defend females from intruding males directly.

• Mating System
• monogamous monogamous
• polygynous polygynous

Female guinea pigs reach sexual maturity in as little as 6 weeks, and males can reach sexual maturity by the time they are 10 weeks old. Pregnant females gestate young for an average of 68 days, which is longer than most rodents (order Rodentia ). Litter sizes can range from 1 to 6 pups. Pregnancy and parturition becomes significantly harder for females older than 6 months of age due to mineralization of their pubic symphyses.

• Key Reproductive Features
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

There is limited information regarding parental investment in guinea pigs. Newborn guinea pigs are precocial and can begin to eat solid food immediately after birth. However, females will nurse their young for as long as 32 days after birth, but otherwise show minimal interest in young. In natural populations, unweaned juveniles have been observed grazing with parents. Some research on paternal behavior indicates that males also care for their young, performing activities such as grooming and playing.

• Parental Investment
• precocial precocial
• male parental care male parental care
• female parental care female parental care
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-independence
  • protecting
    • male
    • female
• post-independence association with parents

Lifespan/Longevity

The average lifespan of guinea pigs is between 5 and 7 years, but there are reports of guinea pigs living up to 12 years in captivity.

Behavior

Guinea pigs are highly social animals. They typically live in herds consisting of an alpha male and several females. They live in areas that protect them from predation, such as rock crevices, areas with dense vegetation, or burrows built by other animals. Guinea pigs are active for nearly 20 hours per day, resting intermittently throughout the day. However, much of their foraging activity is crepuscular. Herd social behaviors include grooming, sitting with body contact, and playing. They also use social vocalizations that range from low and quiet to shrill and loud. Guinea pigs may also chatter their teeth as a sign of aggression towards other guinea pigs or other animals.

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

Communication and Perception

Guinea pigs are born with their eyes open, but do not have well-developed object discrimination or depth perception. Research suggests that guinea pigs rely somewhat on visual cues, but are more heavily reliant on acoustic and olfactory cues to detect predators and communicate with conspecifics. Overall, more research is needed to determine the extent to which guinea pigs use various senses to perceive their environment. However, research has clearly demonstrated that olfactory signals play a large role in intraspecific communication, both within social herds and with unfamiliar conspecifics. Guinea pigs mostly use their anal glands for scent marking, but urine may also play a role in chemical communication. Guinea pigs likely also communicate using tactile stimuli. For instance, sexually active males will nuzzle females as part of the courtship process, and individuals frequently maintain physical contact with other members of their herd.

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

• Other Communication Modes
• scent marks scent marks

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

Food Habits

Guinea pigs are herbivores, mostly eating grasses and other plants at ground level. Common food items for domestic guinea pigs include hay and pellet food. Wild guinea pigs forage most often around dawn and dusk, whereas captive individuals may feed more often during the day or at night. Although their foraging activity levels fluctuate, guinea pigs must eat throughout the day to maintain a high metabolic rate. They are not known to cache food for later consumption. Guinea pigs lack the enzyme L-gulonolactone oxidase and therefore cannot synthesize their own vitamin C. Wild guinea pigs supplement their diets with plant matter that naturally contains vitamin C, and it is extremely important for domestic guinea pig owners to provide supplemental sources of vitamin C through pellets, fruits, or vegetables.

• Primary Diet
• herbivore herbivore
  • folivore folivore
  • frugivore frugivore

Predation

Guinea pigs serve as prey for a wide range of predators in their natural ecosystems. Predators include larger mammals, birds of prey, and reptiles, such as lizards and snakes. Guinea pigs have large eyes and ears and a highly developed sense of smell, which help them detect predators before they become a threat. Guinea pigs also have behavioral adaptations that help them avoid predation. They live in social herds and use vocalizations to communicate the presence of predators to other herd members. If predators are nearby, guinea pigs will seek cover underneath vegetation or among rocks and remain very still. They have dark coloration, which helps them blend in with their environment.

Ecosystem Roles

Guinea pigs are herbivorous herd animals and likely have an influence on the composition of plant communities. They also serve as prey for other mammals, birds, and reptiles, making them an important source of food for other animals in their environments. It is unknown if guinea pigs have other ecosystem roles.

Economic Importance for Humans: Positive

Guinea pigs are an important source of food in parts of South America, such as Peru, and also in parts of Africa, such as Côte d'Ivoire. Because they are small and breed year round, they are relatively easy to raise as part of farming practices. Thus, they serve as a source of income and food for local South American and African communities. Guinea pigs are also popular household pets around the world, and they are commonly used in research laboratories.

• Positive Impacts
• pet trade pet trade
• food food
• research and education

Economic Importance for Humans: Negative

There are no known adverse effects of guinea pigs on humans.

Conservation Status

Due to their limited geographic range and high rates of predation, some wild guinea pig populations are considered to be in decline. However, all wild guinea pig species are still listed as species of "Least Concern" on the IUCN red list, with the exception of Moleques do sul guinea pigs ( Cavia intermedia ), which are listed as "Critically Endangered". Moleques do sul guinea pigs are endemic to a small island archipelago (~10 ha large) off the coast of southern Brazil.

Additional Links

Encyclopedia of Life

Contributors

Kelly Ghiazza (author), Colorado State University, Audrey Bowman (editor), Colorado State University, Galen Burrell (editor), Special Projects.

References

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