Cavies are large-headed, short legged rodents from South America. In the wild, they are crepuscular and live in grasslands in small groups of a male, several females, and their immature offspring. Cavies are entirely herbivorous, wild cavies eat primarily grass. In order to extract as much nutrition from their food as possible, they will eat their fecal pellets after the first pass through their digestive system. They shelter in crevices, vegetation, and burrows dug by other animals, and seem to be uncomfortable out in the open. Genus Cavia tends to inhabit more mesic and wet environments, Microcavia is from arid lands, and Galea may occur in arid or mesic habitats. Rock cavies of the genus Kerodon are something of an exception, as they live in cliffs, rpck piles, and rocky slopes with scrubby vegetation.
One species of cavy has been domesticated, giving rise to the Guinea pig Cavia porcellus. Originally kept for food and fed kitchen scraps, they are now popular pets worldwide.