Far away from their natural habitat, here we see a pair of capybara (Hydrochoerus hydrochaeris) relaxing in the sun at Southwick’s Zoo, Menden, Massachusetts. The largest living rodent in the world, they can grow up to four feet long, and weigh around 140 lbs. Like all rodents their incisors keep on growing throughout their life, so they must chew regularly, to keep the teeth ground down; certainly, the particles of silica in their plant-based diet will help in this. Despite the impressive size of this animal, possibly its closest living relative (other than their smaller ‘cousin’, the lesser capybara – Hydrochoerus isthmius) is the guinea pig! Like guinea pigs, capybara CAN be kept as domestic pets; indeed, at least one of them is broken to a leash, and tours Texas schools on educational visits.
Capybara usually inhabit the pampas and forest areas in Argentina, Bolivia, Brazil, Columbia, Ecuador, French Guyana, Guyana, Paraguay, Peru, Uruguay and Suriname, but wherever their small family groups roam, they are never very far from water (either running or still). Being semi-aquatic, capybara make for the water if threatened, which can be rather unfortunate as they are also the favourite prey of the huge South American snake, the green anaconda (Eunectes murinus) .
If there is one drawback to owning a capybara, it is that they have a rather unsavoury (but absolutely necessary) habit; they are coprophagus. That is, they re-ingest a special form of their dung, called cecotropes, which are produced in the cecum, to enable them to properly benefit from their high-cellulose diet. Unlike some ruminants, who have more than one digestive organ (the cow, for example has four distinct areas of food processing) to aid with the breakdown of a high-volume, low-energy diet, the capybara must let the grasses, herbs and bark which they have eaten pass through their whole digestive tract twice. Usually, this special fecal material is passed during the night, so that these are sometimes called night feces. I would like to point out that many species of rodents produce cecotropes, including rabbits.
Please don’t take the visual appearance of this pair of capybara, with their fairly sparse silvery hair, as being indicative of malnutrition or other illness; this condition is quite normal, and the animals seem very happy with their surroundings at Southwick’s Zoo.