Pygmy Hippopotamus

The pygmy hippopotamus is proof that a hippo does not need to be enormous to be remarkable. Standing about knee to waist high on an adult human and weighing roughly one-fifth as much as its river-dwelling cousin, this secretive forest animal carries all the barrel-bodied character of a hippo in a far more compact frame. It is one of only two hippo species left on Earth, and it may be the more mysterious of the pair.

Native to the dense lowland forests and swamps of West Africa, the pygmy hippo (Choeropsis liberiensis) spends its days hidden in water and thick vegetation and emerges after dark to feed alone. For much of its history it was so elusive that Western scientists doubted it existed at all, brushing off early reports as tales of an undersized common hippo.

Today the species is far better documented, yet it remains poorly understood in the wild and increasingly rare. Fewer than 2,500 are thought to survive across a shrinking patchwork of forest, which places this quiet, water-loving browser among Africa's more urgent conservation stories.

The giant cousin that rules Africa's riversGet to know the common hippo

Taxonomic Classification

The pygmy hippopotamus belongs to the family Hippopotamidae, the same family as the far larger common hippo (Hippopotamus amphibius). These two animals are the only living hippos, the last survivors of a family that was once much more widespread. Within its family the pygmy hippo sits in its own genus, Choeropsis, and carries the scientific name Choeropsis liberiensis, a nod to Liberia, where most of the population lives. American naturalist Samuel Morton formally described the species in 1849.

For many years the animal was placed in the genus Hexaprotodon, and some older references still use that name. Modern work has returned it to Choeropsis, reflecting its distinct evolutionary path. Two subspecies have been recognized. The West African form, C. l. liberiensis, is the one that survives today. A second form from Nigeria, C. l. heslopi, has not been recorded for decades and is now considered extinct.

One of the more surprising facts about hippo evolution concerns their nearest relatives. Despite their pig-like build, hippos are not close kin to pigs. Genetic studies place their closest living relatives among the cetaceans, the group that contains whales and dolphins, from which the hippo lineage diverged tens of millions of years ago.

Physical Description

An adult pygmy hippo measures roughly 5 to 5.7 feet (1.5 to 1.75 m) in body length and stands about 2.5 to 3.3 feet (0.75 to 1 m) tall at the shoulder. Weight ranges from about 397 to 606 pounds (180 to 275 kg), which makes a large individual comparable to a dairy cow and far lighter than a common hippo, which can top 3,000 pounds (1,360 kg). The short tail adds only about 6 inches (16 cm).

The body is barrel-shaped and set on short, sturdy legs, but several features separate the pygmy hippo from its giant relative. Its head is proportionally smaller and rounder, its neck is longer, and its back slopes forward rather than running level. The eyes sit more on the sides of the head instead of bulging from the top, a sign that this hippo spends less of its life submerged. Its feet are less webbed and its toes more spread, both suited to walking forest trails rather than wading deep rivers.

The skin is dark, ranging from greenish-black to brown across the back and sides, with a paler grayish underside. Pygmy hippos lack true sweat glands. Instead they secrete a thick, shiny fluid, sometimes called blood sweat for its pinkish tint, that coats the skin and works as both a sunscreen and an antiseptic against infection. This secretion gives many individuals a slightly oily sheen. Males tend to have a broader muzzle and longer lower canine teeth, the main visible difference between the sexes.

Range and Habitat

The pygmy hippopotamus lives only in West Africa, within the belt of moist lowland forest known as the Upper Guinean forests. Its stronghold is Liberia, with smaller and more scattered populations in Sierra Leone, Guinea, and Ivory Coast (Cote d'Ivoire). The species favors primary and secondary forest close to permanent water, including riverbanks, streams, swamps, and wallows, and it follows well-worn trails and tunnel-like paths through dense swamp vegetation.

Water is central to its daily life even though it feeds on land. During the heat of the day the animal rests in rivers, wallows, or hollows beneath overhanging banks, then moves onto the forest floor at night. This close tie to both forest and water is also the species' weakness, because it cannot easily shift into open or degraded land when its habitat is cleared.

The pygmy hippo has already lost an estimated three-quarters of its former range. What remains has broken into a handful of separated forest fragments, leaving small populations increasingly cut off from one another. Protected areas such as Sapo National Park in Liberia and the Gola Rainforest along the Sierra Leone border now hold some of the most important surviving groups.

Diet

Unlike the common hippo, which grazes on grass, the pygmy hippo is a browser. It feeds on a mix of forest plants, including ferns, broad-leaved herbs, roots, tender shoots, fallen fruit, and semi-aquatic vegetation gathered near water. When a tempting leaf sits out of reach, the animal will rear up on its hind legs and prop itself against a trunk to pull down higher foliage.

Feeding happens mainly at night and takes up several hours, often running from late afternoon until around midnight. The pygmy hippo has a multi-chambered stomach and digests plant matter through a fermentation process similar to that of cud-chewing animals, though it does not actually chew cud, which is why it is described as a pseudo-ruminant. This efficient gut lets it draw ample nutrition from fibrous, low-quality forest plants.

Explore the West African forests it calls homeCountries of West Africa

Behavior

The pygmy hippo is a shy, largely nocturnal, and mostly solitary animal. Adults usually live alone, and the only lasting bonds are between a mother and her calf. Rather than defending strict territories, individuals occupy overlapping home ranges. Males cover the larger areas, roughly 400 to 460 acres (165 to 185 hectares), while females use smaller ranges of about 100 to 200 acres (40 to 80 hectares).

To keep their distance from one another, pygmy hippos rely on scent. They scatter their dung by wagging the tail vigorously while defecating, spreading a marker across trails and vegetation. When two animals do happen to meet, they tend to simply ignore each other rather than fight. By day they rest hidden in water or thick cover, and they sleep on land, sometimes in burrows or hollows, switching resting spots every few days. Though usually quiet and avoidant, a cornered or startled pygmy hippo can defend itself with powerful jaws and sharp canines.

Reproduction

Pygmy hippos reach breeding age at around four to five years old. Mating can take place on land or in water and is not tied to a fixed season, so births occur throughout the year. After a gestation of roughly six to seven months, or about 190 to 210 days, the female produces a single calf. Twins are rare.

A newborn weighs only about 10 to 14 pounds (4.5 to 6.4 kg) and is too weak to follow its mother at first. The female hides the calf in dense vegetation or shallow water and returns several times a day to nurse it. The young grow quickly, reaching many times their birth weight within months, and are usually weaned by six to eight months of age. In the wild, lifespans are thought to run to about 30 years, while protected animals in zoos commonly reach 30 to 50 years, with some passing the half-century mark.

Importance to the World

As a forest browser that travels between water and land, the pygmy hippo helps shape the ecosystem it moves through. By feeding on a wide range of plants and passing seeds through its gut, it aids in dispersing vegetation across the forest floor, and its trails and wallows create small features that other species use. Its presence is also a useful signal of forest health, since a landscape able to support pygmy hippos tends to hold intact water systems and mature vegetation.

The pygmy hippo also holds a place in West African culture that reaches back long before Western science took notice of it. Local communities knew the animal for generations, and it appears in regional folklore, most famously in a tale that describes the hippo carrying a glowing diamond in its mouth to light its path through the forest at night, then hiding the stone by day where no one can find it. Other stories credit it with stranger powers, such as putting out brush fires or shrugging off a hunter's bullets. These legends reflect how deeply this shy, rarely seen animal is woven into the imagination of the forests it inhabits.

Threats and Conservation

The pygmy hippopotamus is classed as Endangered on the IUCN Red List. A 2015 assessment estimated the wild population at roughly 2,000 to 2,500 mature individuals and found it to be declining, though the true figure is uncertain because the animal is so hard to survey. Some references cite a broader range of 2,000 to 3,000.

The greatest threat is habitat loss. Logging, expanding farmland, mining, and road building continue to clear and fragment the forests the species depends on, isolating already small populations. Hunting adds further pressure, as pygmy hippos are killed for bushmeat across parts of their range, and past civil conflicts in the region disrupted both the animals and the efforts to protect them. Although all four range countries grant the species legal protection, enforcement is often limited by scarce resources.

Conservation work now centers on protecting key forest blocks, monitoring the remaining populations with camera traps, and maintaining a managed breeding population in zoos as a safeguard against extinction in the wild. Because many surviving groups sit near international borders, cross-border cooperation among the range countries has become a growing priority.

Its closest living relatives swim the open oceanEndangered whales and dolphins

Takeaway

The pygmy hippopotamus packs the strength and presence of a hippo into a forest-dwelling animal most people will never see in the wild. Its quiet, nocturnal habits kept it out of the scientific record for a long time and still make it one of Africa's least understood large mammals. That mystery is part of its appeal, but it also raises the stakes, because a species this rare and this dependent on intact forest can slip away with little notice. Protecting the West African forests it calls home offers the best hope of keeping this small hippo on the map.

Fun Facts

A viral baby made the species famous. In 2024 a pygmy hippo calf named Moo Deng, born at a zoo in Thailand, became an internet sensation and drew worldwide attention to a species most people had never heard of.
Their sweat acts as sunscreen. The pinkish, oily fluid a pygmy hippo secretes is not blood at all. It shields the skin from the sun and helps fight infection, working as a built-in lotion.
Whales are their nearest living relatives. Despite looking like a stout, oversized pig, the hippo lineage is most closely related to whales and dolphins.
One lived with a US president. In 1927 a pygmy hippo named Billy was given to President Calvin Coolidge by tire magnate Harvey Firestone, then sent to the National Zoo, where he fathered dozens of calves.
They sign their trails with a spin of the tail. Pygmy hippos spread their dung by wagging the tail rapidly while going, painting a scent marker across the forest to keep other hippos at a distance.