If they got to choose their own nicknames, do you think they’d prefer to be called “Water Pigs” or “The World’s Largest Rodents?” Well, the second one not only sounds better, it’s more accurate. Capybaras are rodents, and they can grow to 150 pounds, two feet tall, and up to four feet in length – so they really are the world’s largest! They resemble giant guinea pigs, one of their closest relatives, but their chunky bodies and aquatic habits probably account for that “water pig” reference.

Capybaras live primarily on water plants and grasses, eating 6 to 8 pounds per day per individual. They sometimes will also eat fruits or grains. They also have a (not uncommon) habit of eating their own poop, which has bacteria that helps their stomach break down those tough, fibrous meals. And that doesn’t quite do the trick – like giraffes, cows, and goats, Capybaras regurgitate their food for extra chewing. Speaking of chewing, like other rodents (think mice or squirrels), the Capybara’s front teeth grow continuously, but are worn down by constant grazing. Most of this grazing takes place around dawn or dusk, because during the day they enjoy basking in the sun and swimming to cool down.

These mellow and slow-moving rodents are native to most of South America, and can live wherever there’s a source of water. They need water to drink, to aid in digestion, and very importantly to hide from predators. Once an individual in a Capybara herd gives a distinctive warning bark, the entire group (which can range from 2 to 40 individuals, depending on season and food sources) dives under the surface of the nearest marsh, watering hole, or pond, where they can remain for up to 5 minutes without coming up for air. When they do need to take a breath, they will carefully raise just the top of their heads above the surface, revealing just their nostrils, eyes, and ears in order to assess any danger.

Of course, Capybaras are not necessarily safe in the water, though they are strong swimmers with webbed toes on both front and back feet. Caimans (smaller relatives of alligators and crocodiles) are always looking for tasty rodent lunch as they also lurk beneath and on the surface of the water. On land, Capybaras have to worry about jaguars, pumas, ocelots, eagles, anacondas, and of course, humans.

Newborn Capybaras (usually 2-8 per litter) are the most vulnerable, although they’re precocial when born, meaning their eyes are open, and they can stand, walk, and graze almost from the get go. They are also exceptionally noisy! However, not only are they smaller than the adults, they are slower and tire easily, so it makes sense that whatever the size of a Capybara herd, all the adults protect the young, who can nurse from any available female and also stay close to their parents for the first year of their lives.

Historically, Capybaras have been a vital food source for humans, but unfortunately have been hunted to extinction in some areas. Like all wildlife in the 21st century, Capybaras are also beginning to feel the effects of habitat loss, poaching, and deforestation. The pet trade has also affected their numbers, though they are not yet listed as threatened by the IUCN, like many of the species coming to the Reid Park Zoo expansion. But they’re important! Their “lawn mowing services” and foraging play a vital role in supporting their local ecosystems and the survival of many of their fellow creatures, so zoos like the Reid Park Zoo are keeping a close eye on their populations in the wild. So step right up, folks, to the South America Loop of The Reid Park Zoo, and gaze with wonder upon the World’s Largest Rodents!