Pygmy hippopotamus
Using a series of tunnels and trails through dense vegetation, the pygmy hippopotamus makes its way through the West African jungle. There they mark their territory by spraying poop around with their wagging tails. Unfortunately, the forests which the pygmy hippopotamus inhabit are under pressure. That is why Rotterdam Zoo contributes to the European population management program and to scientific research on pygmy hippos in the wild.
35 years
80 centimetres
1.4 - 1.6 metres
160 - 275 kilograms
Pygmy hippos are medium-sized herbivores with thick, dark grey skin. They are ungulates, with four toes on each foot. Although pygmy hippos often lie in the water, they cannot really swim. Instead, they use their strong legs to push themselves off the bottom.
Pygmy hippos are closely related to common hippos, but there are some key differences. In addition to the obvious difference in size, pygmy hippos have a proportionally smaller head, can only open their mouths to an angle of 150 degrees, and are slightly slimmer.
The pygmy hippopotamus is native to West Africa and is now only found in Sierra Leone, Liberia and Ivory Coast. This species used to also be found in Nigeria, but has not been sighted there recently. It lives in densely forested rainforests with plenty of water.
Pygmy hippopotamuses are mostly nocturnal. Partly because of this and because they live in dense, difficult-to-access rainforests, much remains unknown about the pygmy hippopotamus's way of life.
Pygmy hippos eat many different types of plants, such as ferns, grasses, herbs, aquatic plants and the trunks and leaves of tree saplings. They also enjoy feasting on fruit that falls from the trees. However, they usually have difficulty digesting this.
By excreting the seeds intact, they spread the seeds and fruits of a large number of species, which are also fertilised. This is also important for many other animal species that depend on a wide variety of plant species. Because the pygmy hippopotamus is so important to its habitat, it is also referred to as a “keystone species”. Like a keystone in an arch, it keeps its habitat stable.
Pygmy hippos are solitary animals. This means that they prefer to spend most of their lives alone. Adult pygmy hippos only seek each other out to mate.
It is believed that pygmy hippos each maintain their own territories. However, not much is known about the size of these habitats and how they use them.
All knowledge about the reproduction of pygmy hippos comes from research in zoos. This may differ from the patterns in their natural habitat.
In zoos, pygmy hippos do not have a fixed mating season. Females ovulate for two days approximately every month. Only then do are they receptive to males. After mating, the male and female go their separate ways again.
Unlike regular hippos, which are born in the water, pygmy hippos give birth to their young on land. The mother usually leaves her young in hidden pools, sheltered from predators. She returns every so often to let the young suckle. Only after three to five months, when they are already quite large, does the pygmy hippo begin to follow its mother.
Little is known about predators that hunt pygmy hippos, but they are likely to be on the menu of leopards and Nile crocodiles. Young pygmy hippos are more vulnerable to smaller predators, such as golden cats, civets and rock pythons.
The number of pygmy hippos in the wild continues to decline. Poachers hunt pygmy hippos for their meat and various body parts, such as the skull, legs and toes. These are used in traditional African medicine. Their habitat is also shrinking due to the construction of palm oil, coffee and rubber plantations and fields. As a result, the pygmy hippopotamus has been classified as “Endangered” in the wild.
Because this species lives in dense forest areas, it is uncertain how many pygmy hippos remain. That is why Rotterdam Zoo is working with the IBREAM foundation to train sniffer dogs to track down pygmy hippos. These tracking dogs are partly trained at Rotterdam Zoo, where they are first allowed to smell pygmy hippopotamus dung. The dogs then practise tracking pygmy hippopotamuses by scent in the zoo.
Once in Ivory Coast, the tracking dogs find dung and footprints. Researchers from IBREAM set up camera traps at the locations where they find these. This allows them to count the number of pygmy hippos at these locations. This gives us a better idea of which areas we need to protect urgently.
Rotterdam Zoo takes part in the European population management programme for pygmy hippos. Based on the pedigree of pygmy hippos in zoos, the coordinator decides which animals are best suited to each other for healthy offspring. These young animals are then transferred to other zoos, where they form the next generation. In this way, we are building up a healthy population as a reserve for the wild animals, with the ultimate goal of returning pygmy hippos to their natural habitat when conditions there are favourable.
