What is the pygmy hippopotamus? An updated explanation of its characteristics, ecology, and habitat

What kind of animal is a pygmy hippopotamus? We will explain its characteristics, ecology, and habitat. As its name suggests, it is a very small hippopotamus, and is a cute animal that is also called a little hippopotamus or mini hippopotamus. However, unfortunately, it is an animal designated as an endangered species.

What is a pygmy hippopotamus? Basic stats

The pygmy hippopotamus is a cetacean that belongs to the Hippopotamidae family. It is also called the little hippopotamus or mini hippopotamus. Its English name is Pygmy hippopotamus, its scientific name is Choeropsis liberiensis, and its kanji is dwarf hippopotamus. Its body length is 150-175cm, its weight is 180-275kg, and its shoulder height is 75-100cm. The list of information is as follows.

Japanese（和名）	コビトカバ
English（英名）	Pygmy hippopotamus
scientific name(学名)	Choeropsis liberiensis
classification（分類）	Mammalia、Artiodactylca、 Hippopotamidae、Choeropsis 哺乳綱、偶蹄目、カバ科、コビトカバ属
IUCN Status(保全状況)	ENDANGERED
Length（体長）	150-175cm
Weight（体重）	180-275kg

Taxonomy of the pygmy hippopotamus

• 界 (Kingdom)： 動物界 (Animalia)
• 門 (Phylum)： 脊索動物門 (Chordata)
• 綱 (Class)： 哺乳綱 (Mammalia)
• 目 (Order)： 偶蹄目 (Artiodactyla)
• 科 (Family)： カバ科 (Hippopotamidae)
• 属 (Genus)： Choeropsis または一部では Hexaprotodon
• 種 (Species)： Choeropsis liberiensis

What are the roots and origins of the pygmy hippopotamus?

The pygmy hippopotamus (Choeropsis liberiensis) is a small species of hippopotamus currently inhabiting the forests and wetlands of West Africa. Its primary range centers on Liberia but extends into Sierra Leone, Guinea, and Côte d’Ivoire.

🌍 What were the ancestors of hippos?

The hippopotamus family (Hippopotamidae) is actually an ancient African lineage.

Fossil records indicate that the earliest members of the family date back approximately 21 million years (to the early Miocene epoch).

And perhaps surprisingly,

Hippos 🦛 ←→ Whales and Dolphins 🐋🐬

share a very close evolutionary relationship.

In modern phylogenetics, the Hippopotamidae and Cetacea (whales and dolphins) are considered sister groups. In other words, rather than being closely related to pigs, hippos are the extant land mammals most closely related to whales and dolphins in evolutionary terms.

🦛 When did the pygmy hippo lineage diverge?

This is still a subject of ongoing research.

At one time, there was a theory that pygmy hippos and common hippos diverged more than 10 million years ago.

However, a 2023 study utilizing nuclear DNA

estimated the divergence at approximately 4.04 million years ago,

while another analysis suggested around 2.4 million years ago—

indicating a more recent split. Researchers themselves acknowledge the need for further verification combining fossil and genetic studies.

🌳 Why did they become smaller?

While common hippos grew large and adapted to a lifestyle centered around waterways, pygmy hippos evolved to live within the dense forests of West Africa.

Consequently, it is believed they followed a distinct evolutionary path:

Large, water-centric hippos
↓
A smaller lineage adapted to forest environments
↓
🦛 Modern pygmy hippos

Pygmy hippos are much smaller than common hippos, weighing approximately 160–270 kg. Furthermore, unlike the common hippopotamus, it does not rely heavily on an aquatic lifestyle and is adapted to roaming through forests.

Habitat

The pygmy hippopotamus lives in West Africa, in countries such as Guinea, Côte d’Ivoire, and Sierra Leone.

1. Natural Distribution

Region: West Africa

Liberia

Sierra Leone

Guinea

Côte d’Ivoire

Elevation: Lowland tropical rainforests and wetlands

2. Habitat Characteristics

Prefers wetlands within forests and along rivers

Not completely dependent on rivers or lakes, living in moist areas of jungles

Relationship with Water:

Small and more adapted to terrestrial life than hippos

Uses streams and puddles for bathing and regulating body temperature

Nocturnal, often resting in the shade of bushes or fallen trees during the day

3. Impacts of Human Activities

Habitat reduction due to deforestation and agricultural development

Poaching is also a contributing factor to population decline

What are its characteristics? What kind of creature is it?

Pygmy hippos are basically nocturnal, active from dusk to late at night. They have a small, rounded head, no protruding eyes, and webbed feet between the two toes on their front legs. They are good swimmers and can spend long periods of time in the water, but they also prefer to live on land. Like hippos, they are not covered in fur, so they protect themselves from drying out by bathing in water and mud. Pygmy hippos like to live in the forest.

1. Appearance and Physical Characteristics

Body Length: Approximately 1.5-1.75 m

Shoulder Height: Approximately 75-100 cm

Weight: Approximately 180-275 kg for both males and females

Body Color: Dark Brown to Black-Brown

Skin: Thick and smooth, prevents drying in humid environments

Head: Small and round, with eyes and ears located high on the head

Nose: Short and smaller than that of a hippopotamus

Limbs: Stout, adapted for moving through forests and wading in water

2. Ecological Characteristics

Sylvan and Nocturnal: Rests in the shade of bushes or fallen trees during the day and is active at night

Diet: Herbivorous

Eats leaves, fruits, grass, roots, etc.

Athletics: Smaller than a hippopotamus, it can move agilely through forests

Relationship to Water: Uses streams and puddles for bathing and regulating body temperature

3. Behavior/Personality

Gentle but timid

They tend to live alone or in pairs, not in groups

They quickly hide in the bush when they sense a human or predator.

4. Characteristic Impression

They are thought of as a small, forest-dwelling hippopotamus with smooth, dark brown skin, a nocturnal, stealthy animal.

They are better adapted to life on land than hippos and are adept at walking through the forest.

What is their personality like?

Pygmy hippos sometimes live in family groups consisting of pairs or their young, but they can also live alone.

1. Basic Personality

Timid and cautious

If they sense a predator or human, they will quickly hide in bushes or near water.

Gentle Personality

Not aggressive, they tend to avoid conflict.

Mainly solitary or pair-based.

They do not form groups and tend to be territorial.

2. Sociality

Soliton or pair-based.

Males defend their own territories.

Females are active within their territories while raising their young.

Communication is limited.

They communicate with their peers and young through nose and body movements and low vocalizations.

3. Behavioral Characteristics

Nocturnal, they rest quietly in bushes during the day.

Curious, but cautious.

Approach new objects and environments cautiously.

Bathe in water and mud to regulate body temperature and protect their skin.

What is their ecology?

Pygmy hippos are herbivorous, eating grass, rhizomes, leaves, fruit, etc. They reproduce viviparously. They are monogamous and have a gestation period of 180-210 days. They can give birth to one young at a time, and their lifespan is 10 to 20 years.

1. Behavior

Nocturnal: Active primarily at night, resting in the shade of bushes or fallen trees during the day

Mainly forest-dwelling, terrestrial

Does not depend on rivers or water sources; instead, lives in forest swamps and streams

Live alone or in pairs

Does not form groups; acts territorially

2. Diet

Herbivorous

Main diet:

Leaves, shoots, grasses, and fruits

Supplementary intake of twigs and roots

Moves through the forest in search of food

Bathes in water and mud to protect skin and regulate body temperature

3. Reproduction

Estrous/Breeding: Breeding is possible year-round, not dependent on a specific season

Gestation period: Approximately 6-7 months

Litter size: Usually one cub

Rearing:

Mothers primarily nurse and protect cubs

Cubs observe their mothers’ behavior and learn food gathering and transportation techniques

Sexual maturity:

Females: 3-4 years old

Males: 4-5 years old

4. Social Structure

Live alone or in pairs

Males defend their territories and focus on females and their young

Limited contact with other individuals to avoid conflict

5. Adaptation and Survival Strategies

Agility to move quickly through forests

Nocturnal behavior to avoid predators (large cats, canines)

This terrestrial hippopotamus is able to live in forests without relying on water or wetlands.

Do they have any natural enemies?

The natural enemies of the pygmy hippopotamus are leopards and humans.

About Pygmy Hippopotamus Cubs

This article provides an easy-to-understand summary of pygmy hippopotamus (Choeropsis liberiensis) cubs, from birth to growth.

1. Characteristics at Birth

Gestation Period: Approximately 6-7 months

Litter Size: Usually one pup (twins are extremely rare)

Birth Weight: Approximately 4-6 kg

Body Length: Approximately 40-50 cm

Appearance:

More rounded and stocky than adults

Skin is smooth and slightly light brown in color

Large eyes, giving them an overall “stuffed animal-like” appearance

2. Behavior Immediately After Birth

Able to stand and walk within a few hours of birth

Stay close to their mother and spend their time quietly in the jungle

If they sense danger, they will quickly hide behind their mother or in the bushes

3. Changes in Nursing and Diet

Nursing Period: Approximately 6-8 months

Breast milk is their main source of nutrition

From a few months after birth:

Begins nibbling on leaves and fruit

Learns food selection by observing their mother’s behavior

4. Growth and Learning

Cubs follow their mothers as they:

Travel routes through the forest

Location of water sources

Dangerous areas and safe hiding places

They play less, but by walking around, they develop leg strength and stamina.

5. Socialization and Independence

Primarily a mother-child lifestyle

They do not live in groups, so they have little contact with other individuals.

Independence period: Approximately 2-3 years of age

Until then, they live within their mother’s territory.

6. Personality of Cub

Very timid and quiet

Curious, but quickly returns to their mother

They acquire the ability to avoid danger early on.

Is the pygmy hippopotamus an endangered species?

The pygmy hippopotamus is an endangered species. It is listed in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), so international trade is strictly restricted. The pygmy hippopotamus is a rare animal with a small population, and is considered one of the three most rare animals in the world along with the giant panda and okapi. For this reason, the destruction of habitats due to development, water pollution, and overhunting are progressing, which can be said to be critical. It is already extinct in Nigeria.

Current Situation and Background

The International Union for Conservation of Nature (IUCN) has listed the pygmy hippopotamus as Endangered (EN) (highest level of threat).

The estimated wild population is very small, confined to West Africa (primarily Liberia, Sierra Leone, Guinea, and Côte d’Ivoire).

It is believed that the population continues to decline due to deforestation and hunting (e.g., for consumption).

Main Threats

Deforestation and Land Development

Wild Capture and Hunting

Habitat Fragmentation Leading to Decline in Genetic Diversity

These threats have a significant impact on wild pygmy hippos.

Can the pygmy hippopotamus be kept as a pet?

As mentioned above, the pygmy hippopotamus is designated as an endangered species and is also listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), so international trade is strictly restricted. Therefore, it is extremely difficult to keep it as a pet.

① Is it legally possible?
❌ Almost impossible

The pygmy hippopotamus is an IUCN Endangered Species (EN)

Listed in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)
→ International trade for commercial purposes is prohibited

In Japan:

Extremely strict import permits

Exceptional approvals are granted only at zoos and research institutions

Individuals are not permitted to import or purchase them as pets

② Feasibility of keeping them
❌ Impossible for an average household

Although the pygmy hippopotamus is small…

Weight: Approximately 200 kg

Large herbivores with strong jaws and fangs

Nocturnal and highly active

Dedicated:

Large site

Water source (constantly clean water)

High humidity

Veterinary care

➡️ These require zoo-level facilities

③ Personality Issues

Generally docile, but
very dangerous if startled

Due to their timidity:

They become aggressive when stressed

Risk of lunging and biting

Not fully domesticated

④ From an animal welfare and ethics perspective

Wild populations are small

Breeding is difficult

Keeping them as pets is strongly discouraged from conservation perspectives

Current captivity is limited to:

Zoos

Rescue facilities

Breeding programs