Colours of Wildlife: Pygmy Hippo
Created | Updated May 19, 2013
Pygmy Hippo
Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"
Today I bring you the Pygmy Hippopotamus, Choeropsis liberiensis. This lovely animal doesn't occur in the wild in South Africa, being restricted to tropical rainforests in West Africa – Liberia, as the species name indicates, but also Guinea, Sierra Leone, and the Ivory Coast. Some have been recorded from Nigeria but it's not clear if those still survive. The species is very threatened in nature, but there are many of them in captivity. The name Choeropsis means ‘resembling a hog'.
I know this species from having seen it in zoos, and more specifically, at the Potgietersrus (now Mokopane) Game Breeding Centre, where some used to be kept in a large enclosure with ponds. I haven't been there in a long time so I don't know if they are still there. But I always enjoy seeing them!
Not Just a Smaller Copy
Pygmy hippos differ from hipposmainly in being smaller: they are only about half as tall and long, and weigh only 180-275 kg (400-600 lbs). This makes them not exactly tiny, but then regular hippos are so much bigger! Pygmy hippos are more a manageable size; they are therefore not dangerous to humans as their bigger relatives. They still have vicious, sharp teeth – their upper canines have two sharp points each, unlike the single-tipped teeth of hippos and indeed most mammals. These little hippos can certainly defend themselves against predators; I haven't heard of them ever killing humans, though.
Other aspects in which the pygmy hippos differ from the larger ones are that they are proportionately longer limbed and with longer necks. Their heads are also much smaller and shorter compared to their bodies. Their eyes and nostrils, while being set high on the head, do not protrude above it the way those of big hippos do. This is because they do not spend so much time in the water, roaming in the forest more. They do like swimming and wading in water, though, and like their bigger relatives their skins need to remain moist. The rainforests where they live have high humidity and receive very heavy rainfall, and there are many streams, pools and rivers in them. Like big hippos their skins secrete a pinkish fluid with antiseptic and sunscreening properties.
A Forest Hippo
Regular hippos are grazers, as I noted in my article on them, and live in areas where lush grass grows on or around riverbanks. Pygmy hippos are more diverse, eating grass but also other forest plants such as ferns, herbs and broad-leaved plants. They will also eat fallen fruit. They browse mostly at night, spending the day sheltering in water or in burrows in river banks. They clear tunnel-like paths through the dense forest vegetation in their nightly wanderings. They mark these trails, defining their territories, by dung-splattering as I describe in my article on the regular hippos. They are more solitary than big hippos, not congregating in large herds, but at most in pairs, or offspring staying with their mother for a while. They are not as noisy as big hippos, but have been recorded grunting, snorting, squeaking and hissing. Males are less aggressive than those of big hippos, and they fight far less.
While big hippos mate and give birth in water, pygmy hippos do those things either on land or in the water. The cow can start having babies at around three years of age. The babies can swim upon being born. They are tiny compared to the adults, weighing 4.5-6 kg (about 10-13 lbs). The mother suckles them on land, lying on her side, and leaves them hidden in the water while she goes out to forage. She returns to them several times a day for suckling. They are weaned at about eight months' age. Pygmy hippos can live more than fifty years in captivity but probably rarely reaches such an age in the wild.
A Contracting Range
While regular hippos are still found all over Africa, pygmy hippos now inhabit a very small range. The rainforests of West Africa have been shrinking alarmingly for a long period because of logging and land clearing to make way for the increasing human population. What was originally a vast belt of continuous forest has now been cut up into a large number of small patches.
But not long ago pygmy hippos ranged much more widely, into North and East Africa. Very similar species lived in Asia and also Madagascar. These have not yet been studied very intensively; the Asian species are placed in the genus Hexaprotodon (meaning ‘six front teeth' denoting the six forward-pointing incisors in each jaw), in which the pygmy hippo is also sometimes placed. The Madagascan hippos included three species, of which at least one might have been a close relative of the surviving pygmy hippo, also inhabiting dense forests. Sadly, all Asian and Madagascan hippos are now extinct. So today the pygmy hippo is the last remnant of this line of small forest hippos. It appears likely that it and the others of this line have diverged from large hippos something like 8 million years ago. Actually the bigger hippos could more realistically be said to have diverged, since the pygmy hippos are much closer in size and build to the first hippos known from fossils; they stayed pretty much the same while some of the other hippos, of which just one species survives today, became much larger.
Other Small Hippos
There used to occur other small hippos in Europe, specifically on the islands of the Mediterranean: Malta, Sicily, Cyprus, Crete, and probably others also. The smallest of these was similar in size to the living pygmy hippo. But these hippos were not close relatives. Instead they were descendants of much larger hippos: perhaps the huge extinct hippo species, Hippopotamus gorgops or Hippopotamus antiquus, or perhaps from northern populations of the surviving hippo. What happened is that, during the periods of heaviest glaciation of the ice ages, so much water was locked up in ice sheets that the sea level dropped drastically worldwide. Islands that used to be separated from the mainland by broad straits were now either connected to the mainland, or separated from it by narrow straits over which hippos (and a few other animals like elephants) could swim. They took advantage of this and colonized these islands. Then, when the ice sheets melted (and this happened many times during the Ice Ages – the periods in which the ice melted and retracted are called interglacials) the sea levels rose and the islands became isolated again. When this happened the animals were stuck on the islands. Large animals like elephants and hippos need lots of food, perhaps more than a smallish island can supply. But then they shrunk in body size (over many generations of course), meaning that they needed less food and could more easily survive. This is called ‘island dwarfism' and it has happened many times to many different kinds of species in the course of evolution. And while large creatures tend to become dwarfed, the opposite also happens, small creatures becoming large. Small mammals and many kinds of birds that colonize islands often find them devoid of large predators, and therefore can afford to become large, conspicuous and slow. So on the Mediterranean islands back then one could have witnessed tiny elephants and hippos alongside giant rabbits, hedgehogs and swans!
Folklore
Pygmy hippos only recently became known to ‘western' science, having been discovered in the middle of the nineteenth century. They've been known to locals for much longer, of course. One legend goes that a pygmy hippo carries a shining diamond in its mouth to provide light for it on its nightly wanderings. The hippo buries this diamond in a secret place by daytime. A hunter, it is said, can have this diamond if he can catch a pygmy hippo at night. Another myth goes that baby pygmy hippos don't drink milk from their mums, but lick up her skin secretions instead. Yet another myth says that these secretions make their skins bullet-proof. Another says that these hippos will douse bush fires by spraying water from their mouths over them, and then eat the coals and ashes like the Hooganod.
