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Info on pygmy hippos

The pygmy hippopotamus (Choeropsis liberiensis / Hexaprotodon liberiensis) is a non-ruminant even-toed ungulate belonging to the family hippopotamuses. Its closest relative and currently the only other member of this family is the common hippopotamus.

The pygmy hippo is sometimes divided into 2 subspecies according to the region it lives in: C. l. liberiensis (Liberia, Sierra Leone, Guinea and Ivory Coast) and C. l. heslopi (Nigeria). However, the last reliable reports about C. l. heslopi date back to the mid twentieth century, it was never captured nor studied in the wild and is likely to be extinct. All research and all zoo specimens belong to the C. l. liberiensis subspecies.

Distribution

The pygmy hippo lives in West Africa. The biggest population, as can be guessed from the second part of its scientific name, occurs in Liberia but smaller groups inhabit also neighbouring countries - Sierra Leone, Guinea and Ivory Coast. The range of the pygmy hippo mostly doesn't overlap with that of the common hippo and both species are not very likely to meet in nature.

The area of the pygmy hippo hasn't changed much since prehistoric times but the current population is far more fragmented. At most 3,000 animals are estimated to remain in the wild, hence the pygmy hippo is listed in the Red List of Threatened Species as endangered. The major cause of the decrease in numbers of pygmies is habitat loss (logging) and hunting for meat. On the contrary, their teeth are not subject of illegal ivory trade as in the common hippo.

Pygmy hippos live in forests in proximity of swamps, marshes or rivers. Because they're active mainly at night and the places they live in are often inaccessible for people, they were long totally unknown outside of West Africa. The first reports about a minihippo appeared in 1841 but it took more than 70 next years until scientists finally believed in its existence. And even after another hundred years there's still relatively little we know about pygmy hippos. The majority of our knowledge comes from zoological gardens where the pygmies fortunately breed well.

About their body

In comparison with the big hippo, the pygmy hippo is a total mite. Nevertheless, it's not a small animal. It weighs roughly 180 - 275 kg (400 - 600 lbs), measures 1.4 - 1.6 m (4.6 - 5.2 ft) in length and 0.7 - 0.9 m (2.3 - 3 ft) in height; its tail is 15 - 20 cm (0.5 - 0.7 ft) long. Females are apparently smaller and lighter than males.

The body of the pygmy hippo resembles that of the common hippo but there are some differences. Compared to the common hippo, the pygmy is relatively taller and shorter and its back is not parallel with the ground but slopes markedly forward - a likely adaptation to pass more easily through dense vegetation. The pygmy hippo has also proportionately longer legs, narrower feet, the two outer toes shorter and located further from the others, sharper hooves and just a slight inkling of swimming webs. Its head is smaller with eyes and nostrils less protuberant and eyes are not located so much at the back of the head. All these differences suggest that the pygmy hippo is far less fixated on water and that it spends pretty much time on land. However, its body shows also some adaptations to live in the water, such as muscular valves to the ears and nostrils.

A pygmy hippo's skin, with a stout layer of fat below, is very thick but sensitive. Its colour is dark brown to black, darker than in the common hippo. It must be kept moist, otherwise will crackle. The moisture is provided by special subdermal glands ("ordinary" sweat glands are missing) which secrete a strange reddish liquid. With physical exertion, this liquid changes into white foam.

A pygmy hippo's head differs from the common hippo not only by eyes but also by shape - it doesn't broaden so much at the end and the muzzle, overgrown with soft bristles, is rounded. The mouth of an adult hides 34 teeth, 2 less than in the common hippo - 2 incisors, 1 canine, 3 premolars and 3 molars in each half of upper jaw, 1 incisor, 1 canine, 3 premolars and 3 molars in each half of lower jaw. Just like in the common hippo, the pygmy hippo's milk set of teeth consists of 32 teeth - 3 incisors, 1 canine and 4 premolars in each half jaw. Canines of an adult pygmy are huge and can cause serious injuries. That's why zookeepers treat him with respect.

The stomach is divided into four sections but the food doesn't return to mouth for another chewing as in ruminants. A pygmy hippo's guts are about 20 m (66 ft) long, the appendix is missing.

The life of a pygmy hippo

Pygmy hippos are solitary animals. Most observations are of single specimens although pairs and threesomes are not unusual. It's not clear how long two pygmies stay together and whether they constitute a monogamous pair but it's more likely that they seek each other only for mating.

Male pygmy hippos' home range is about 185 ha and overlaps areas of several females, whose range is about 40 - 60 ha. However, it is apparently not a territory in the strict sense of being a defended area from which other males would be excluded. When two animals meet, they tend to ignore each other rather than threaten or fight. This implies that pygmy hippos apparently aren't territorial.

By day the animals usually stay in a swamp or river and sometimes even make use of dens washed out in river banks, which they enlarge to fit their needs. They reputedly rest in the same spot for several days in a row, before moving to a new spot. When disturbed, pygmy hippos flee out of the water trying to save themselves by a run. They come out to feed in the evening or at night and spend about six hours searching for food. They use regular paths or better tunnels to move through the forest and mark them by dung, which they scatter by their tail. As they're herbivorous, they feed on plant food - ferns, fruits, leaves, twigs or rootlets. They like also grass but there's little of it in the forest. They nip off and collect food by their lips.

Except for man, an adult pygmy hippo has probably no enemies, possibly can sometimes fall sacrifice to a leopard. Juvenile pygmies are more threatened - by leopards, pythons, crocs... Very young or newborn calves can also be killed by the golden cat, civet or ratel.

The life span of pygmy hippos is up to 50 years in captivity and it's likely to be lower in the wild but accurate data are unknown.

Reproduction

Pygmy hippos mate in the water or ashore. Gravidity lasts about 180 - 210 days, i.e. 6 - 7 months. Captive births can occur any time throughout the year, data from nature are unknown. However, wild babies are also very likely to be born all year round because there's enough food in the rainforest in whichever season.

According to zoo observations, pygmy hippos give birth either ashore or in the water and only 1 calf, weighing 4 - 7 kg (8.8 - 15.4 lbs), is born as a rule. How often twins are born is unknown.

For the first few weeks, the mother leaves her young hidden in a swamp when foraging for food. This habit is advantageous for both - the mother doesn't have to look after her calf while searching for food and the calf doesn't uselessly waste its energy by running about the forest. In addition, it's well hidden from predators; the water absorbs its smell. The mother returns to her baby several times per day to suckle it. Nursing takes place on land or in the water. The mother has two inconspicuous teats on her belly and lies on one side while suckling. The inconspicuousness of the teats gave origin to a legend of natives which says that the calf doesn't suck but feeds on foamy secretions of its mother's body which it licks off.

The baby quickly puts on, having some 80 kg (176 lbs) at one year of age. It's weaned at 8 - 12 months but stays with its mother for several years.

Pygmy hippos reach the sexual maturity at the age of 3 - 5.

S. K. Eltringham, The Hippos
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