Kerodon rupestris is endemic to the semi-arid region of northeastern Brazil known as the Caatinga.

Biogeographic Regions: neotropical (Native )

Kerodon rupestris is a hystricomorph rodent very similar in appearance to Cavia species. The tail is absent or vestigial, adult weight is around 1000 g, and the ears are short. Adult length is between 200 to 400 mm and is occasionally longer. Rock cavies have whitish throats, while other upper parts are generally grayish, and the stomach is yellowish brown. The rostrum is longer than other caviids and the incisor to premolar diastema is proportionally greater. Unlike other caviids, K. rupestris has blunted nails on all digits excepting a small grooming claw on the outermost digit of the foot, and the hands and feet are additionally padded with a leather-like surface. Other than size differences, day-old highly precocial young appear very similar to adults.

Range mass: 900 to 1000 g.

Range length: 200 to 400 mm.

Range basal metabolic rate: .41 to .59 cm^3 oxygen/hour.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike

• Terrestrial

Within the Caatinga region, K. rupestris is confined to rocky terrain characterized by large granitic boulder outcroppings. In these outcroppings, rifts and hollows create space for K. rupestris to dwell and avoid predation. Environmental conditions are unpredictable; annual rainfall varies between 1000 and 400 mm, and flooding and drought can occur throughout the year.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: savanna or grassland ; scrub forest

Although known as a habitat specialist, rock cavies are generalist folivores where diet is concerned. In their unpredictable Caatinga environment, drought often leaves trees leafless. During dry periods, vegetation continues to grow in the rock piles where rock cavies live, allowing colonies to live through periods of low productivity. During periods of high productivity, rock cavies feed on leaves, buds, flowers, and bark, most often foraging from the ground or on tree branches. In captivity, rock cavies eat a variety of fruits and vegetables.

Plant Foods: leaves; wood, bark, or stems; flowers

Other Foods: dung

Primary Diet: herbivore (Folivore ); coprophage

Rock cavies are the only mammal endemic to the Caatinga region of Brazil. Because of their specializations towards living in such an unpredictable environment, few other mammals continually interact with rock cavies. Dry periods drive out many other mammals, and no specific predators are mentioned in the literature. Presumably, however, local avian and mammalian carnivores prey on rock cavies. As generalist folivores, rock cavies impact a variety of local flora through consumption of leaves, bark, and flowers. Parasitic nematodes are also found in the large intestines of rock cavies.

Commensal/Parasitic Species:

• nematodes (Nematoda)

Using sound or smell, rock cavies are able to detect predators approaching from a distance. The confines of surrounding rock hollows provide predator protection, and "alarm whistle" vocalizations are used to alert the colony to take refuge when needed. Once the repeated high pitch whistle is heard, surrounding individuals echo the call. When predators are seen approaching, individuals flee into surrounding rocks. This decreases the chance of any one individual indiscriminately running toward the approaching predator. The predator avoidance strategy employed by rock cavies is presumably a specialist adaptation to their rocky habitat which limits field of view and visual predator detection.

Anti-predator Adaptations: aposematic

Rock cavies produce a variety of vocalizations, many of which are thought to represent anxiety or fear. Five distinct vocalizations are described, yet few are thought to directly communicate information to other individuals. Although scent marking is common among other caviids, rock cavies are not known to regularly scent mark. Rather, posturing and tactile interactions allow rock cavies to communicate, as individuals are often in close proximity around rock pile colonies. Social rank is continually communicated through allogrooming and agonistic interactions which include head thrusts and chases.

Communication Channels: visual ; tactile ; acoustic

Perception Channels: visual ; acoustic

Rock cavies are relatively long lived for inhabiting such an unpredictable environment. In captivity, individuals live as many as 11 years. In the wild, the probability of an individual living to 3 years of age is 91%.

Average lifespan

Status: captivity: 11 years.

Average lifespan

Status: wild: 5 years.

Male rock cavies defend hollows and dens made by the surrounding granitic boulders. Females seek refuge in these dens and a system of resource-defense polygyny emerges as a result. Mates are easy to find, therefore, a well established dominance hierarchy exists among males. Dominant males defend prized rock piles with large harems and are able to mate more frequently than subordinates. During mating, multiple males encircle one female in order to prevent her escape. Often these males include the dominant male and his progeny, as all others are treated aggressively. After encircling, the dominant male mounts the female to copulate.

Mating System: polygynous

Rock cavies breed year round and give birth to 1 to 3 highly precocial young per pregnancy, although singleton births are most common. They have a gestation period of 76 days which is notably longer than other caviids. Infants are weaned at 35 days, and juveniles reach sexual maturity around 133 days. Small litter size, comparatively long gestation period, and other reproductive parameters (i.e. low birth mass: maternal mass ratio) are considered specialist adaptations to rigid maternal energy constraints and a highly unpredictable environment.

Breeding interval: Female rock cavies have post-partum estrous and give birth up to three times a year.

Breeding season: Rock cavies breed year round.

Range number of offspring: 1 to 3.

Average number of offspring: 1.5.

Range gestation period: 75.36 to 76.33 days.

Average gestation period: 76 days.

Range birth mass: 75 to 90 g.

Average birth mass: 85 g.

Average weaning age: 35.17 days.

Average age at sexual or reproductive maturity (female): 133 days.

Average age at sexual or reproductive maturity (male): 133 minutes.

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

Rock cavies exhibit well developed parental care. Both sexes engage in grooming, huddling, and indirect social behaviors which rear the young until independence. Weaning occurs at 35 days, yet young have been observed foraging and eating vegetation as early as 2 days after birth. Early consumption of whole food suggests that suckling behavior may involve socialization as well as nourishment. After weaning, juveniles live in their fathers' den. Males born to the dominant male are not treated aggressively by their father. Living among his harem allows for increased socialization and a potential chance to become dominant in the future. Females born to dominant males live in the harem as potential mates, yet aggression from other females, including the mother, is common. Young females may leave the den as a result.

Parental Investment: precocial ; male parental care ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female); post-independence association with parents

Although habitat destruction and hunting have threatened rock cavies in the past, K. rupestris is currently listed as "least concern". Numerous protected areas currently provide refuge from hunting and habitat loss.

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

There are no known adverse affects of K. rupestris on humans.

Humans native to northeastern Brazil regularly hunt rock cavies for meat. Efforts have even been made to domesticate them as a reliable food source in areas afflicted by drought and poverty. Although not common, rock cavies can be kept as pets as well. Medicinal uses of K. rupestris include rubbing rock cavy fat under the eyes to ease "tired eyes" and mixing rock cavy manure with coffee to treat effusion.

Positive Impacts: pet trade ; food ; source of medicine or drug