The World’s Biggest Rodent

1Mice, squirrels, and hamsters belong to one family: the rodents. A rodent’s two front teeth never stop growing, so it must wear them down. That’s why you almost always find one chewing something, a seed or a root or a strip of bark. A beaver’s teeth are the famous example, orange and strong enough to fell a tree.

2The world’s biggest rodent is the capybara, as tall as a large dog and as heavy as a man.

Rivers, Grass, and Mud

3Every wild capybara lives in South America, most of them in Venezuela and Colombia, where wide rivers cross flat, grassy land. Others live at the edge of the rainforest, under trees so thick that almost no sunlight reaches the ground.

4No American animal is more at home in water. Rivers, streams, ponds, and muddy channels are its roads, and it travels these waterways the way we travel a highway. Somewhere close by there is always water to slip into.

5Early in the morning capybaras wander onto the grass, going nowhere in particular: walk a little, eat a little, walk again.

An Afternoon in the Water

6A capybara is a herbivore. It eats no meat at all, not a fish, not an insect. Grass fills most of its stomach, with water plants, soft bark, and fallen fruit. Give it a tangerine and it eats the little orange fruit whole, skin and all.

7By the middle of the afternoon the sun is too hot for a thick-furred animal. One by one the capybaras shuffle to the river, taking short, slow, sliding steps, and sit down in the shallows. An hour of soaking is the best part of the day. Only their eyes, ears, and noses stay above the surface.

Built for Swimming

8Capybaras are powerful swimmers. Skin stretches between the toes of their back feet, turning each foot into a paddle that pushes water the way a diver’s flippers do. Their strokes are coordinated: legs and body all working together at the same moment, like an Olympic athlete down a lane.

9When a jaguar appears, a capybara dives. It slides under the surface the way submarines drop beneath the sea and stays down five minutes, holding its breath. In brown water it sits almost invisibly: right in front of you, and you cannot see it. It knows every deep pool and reed bed, and swims through a thick tangle of plants without slowing.

The Calmest Animal in South America

10Capybaras may be the calmest animals in South America. They are peaceful and almost never fight, and they are patient in a way few animals are: things climb on them and they let it happen.

11Birds land on their backs and stay for hours. Monkeys ride across a field on a capybara’s shoulders. Turtles, ducks, and even small wild cats have been found sitting on a resting capybara, which does not seem to mind these passengers at all. Other animals trail after capybaras all day, and these followers sleep pressed against them, using their warm sides as pillows.

12People take photographs of this wherever capybaras live. In almost every picture the animal is standing still or lying down, watching the world through half-closed eyes, its mouth turned up at the corners. It is not really smiling, because a capybara’s mouth is simply built that way, but it is hard to look at that face and believe it.

How Capybaras Talk

13A capybara is almost never alone. Capybaras live in groups of 10–20 animals, and when the dry season comes several groups may gather into a herd of a hundred.

14A capybara doesn’t roar or howl. It clicks, purrs, barks softly, and when something is wrong it lets out a sharp whistle. The group is always listening. Because one animal stays awake, the others can rest. The moment the whistle sounds they turn in one coordinated rush, every animal moving the same way at the same time, and they are in the river before the danger arrives.

Danger and a Long Life

15The danger is often an anaconda, a snake heavy enough to wrap around a capybara and squeeze. Jaguars hunt them on land, and caimans wait in the shallows.

16Even so, a wild capybara’s lifespan is about 8–12 years, which is how long one usually lives from birth to old age. In a zoo, where nothing hunts them, capybaras live longer.

17Capybaras matter to South American wildlife. They keep the grass low, carry seeds from place to place, and feed a great many other animals. A river without capybaras would be a quieter river, and an emptier one.