Pygmy hippos are rarely found, easily recognizable and huge mammals that have always had a relatively small overall population. These animals are closely related to the hippopotamus, inhabiting West Africa. Pygmy hippos compose a separate class of animals. Like the hippopotamus, they are semi-aquatic creatures, although they spend a considerable part of their time on the ground. A constant source of water is a vital life condition for Pygmy hippos, since it prevents their skin from drying and helps them control body temperature.
The natural range of this species covers West Africa, including countries such as Liberia, Sierra Leone, Guinea and the Ivory Coast. Within this territory, Pygmy hippos inhabit midst parts of tropical lowland forests with dense cover. These semi-aquatic mammals live and construct burrows along swamps and rivers, constantly remaining in close proximity to water.
Pygmy hippos tend to lead solitary life, avoiding conspecifics. When encountering each other in the wild, hippos usually ignore one another. Each individual defends its territory through fecal marking. These mammals socialize only during the mating season as well as when rearing their offspring. They generally exhibit nocturnal activity, being most active from the late afternoon to midnight. They spend around 6 out of 24 hours per day feeding. The daytime hours are spent resting in the water or on the river bank. Pygmy hippos sleep on the ground, typically in caves of burrows. Each site is used for only a few days, since these hippos change their sleeping quarters once or twice a week. Although normally silent, they may sometimes give out snorting, grunting, hissing and squeaking sounds.
These mammals maintain strictly herbivorous or plant-based diet, composed of herbs, broad-leaved plants, grasses, semi-aquatic plants, herbaceous shoots, forbs, sedges, ferns as well as occasional fallen fruits.
Pygmy hippos in captivity are known to exhibit monogamous mating system, where each individual has only one mate. Those in the wild are thought to be polygynous, since territory of each male overlaps with these of multiple females. Some researchers suggest that Pygmy hippos are polygynandrous (promiscuous) with both males and females breeding with multiple mates. Captive Pygmy hippos do not have a specific breeding season, but instead can mate at any time of the year. Individuals breed once every 7 - 9 months. A single baby is born after 184 - 210 days of gestation. The newborn hippo lives alone as the mother forages, visiting to suckle the baby 3 times a day. The calf is weaned at 6 - 8 months old and is reproductively mature at 3 - 5 years of age.
Pygmy hippos are currently threatened by a number of factors, which negatively affect the small population of this endangered species. To mention just a few, deforestation, hunting, development agriculture and civil conflicts are among serious threats to these animals. Although Pygmy hippos are legally protected throughout their range, the total population is decreasing due to scarcity or absence of suitable resources.
According to the IUCN Red List, the population number of Pygmy hippos is around 2,000-2,499 mature individuals. According to the Pygmy Hippo Foundation resource, the total population of this species in the wild is about 2,000 individuals, majority of which live in Liberia and the rest inhabit Sierra Leone, Guinea and the Ivory Coast. Currently, Pygmy hippos are classified as Endangered (EN) and their numbers continue to decrease.
The ecological niche of this species is insufficiently explored, although Pygmy hippos are likely to impact plant communities of their range through their plant-based diet.