The hippopotamus, a well-protected animal

The hippopotamus, Hippopotamus amphibius, has no special status and is considered a low risk and least concern (LR/LC) species.

Hippos in the water. © Pierre Poilecot

Despite its large range, this ungulate is protected throughout West and Central Africa. The meat and skin of the hippopotamus and theivory of its teeth are indeed sought after and the species has been the subject of significant poaching. In Benin, its meat is sold for up to 200,000 FCFA/kg.

The hippopotamus is distributed in all the rivers, lakes and ponds, lined with vegetation, of sub-Saharan Africa, from Senegal to East and southern Africa. They sometimes use estuaries which lead them to the sea (Tanzania, Senegal [Casamance]Guinea Bissau, Gabon).

The global population is currently fragmented, often made up of small sub-populations sensitive to disasters (droughts), to the reduction of habitats, as well as to genetic problems. The subspecies present in Chad and Nigeria (H.a. tschadiensis) is classified as vulnerable.

The hippopotamus locally causes damage to crops resulting in man/wildlife conflicts. It is subject to frequent fish poisoning by fishermen and farmers when damage is caused to their nets and fishing boats and to the crops deposited on the edge of the banks. Hippos are fully protected by the Algiers (1969) and CITES (1990) conventions. In all of the countries (countries south of the Sahara) in the hippopotamus’ range, the species is fully protected, that is to say hunting is prohibited.

How does a hippopotamus live?

This large herbivore is semi-aquatic and spends much of the day in the water and resting on the sandbanks of streams and streams. It avoids densely wooded banks and fast-flowing waters. An excellent swimmer, he can stay underwater for up to six minutes and walk on the bottom. The hippopotamus, very gregarious, sedentary and territorial (only in water), lives in herds of 5 to 15 individuals, but sometimes many more, composed of females and young around gravitate the males according to their hierarchical position. Dominant males fiercely defend their territory through fights that can lead to the death of one of them. Old animals are thus often scarred with scars.

The short but powerful queue allows the dung, of a soft consistency, to disintegrate when it is issued and spread on the bushes as a mark of territory (although it is not considered a territorial animal on the land) . These marks could in fact serve as “beacons” to facilitate the evolution of animals in the feeding areas around their home range. The excrement thus deposited, mixed with urine, also marks out the paths used by the animals. The deposition of faeces and urine could also have an important social function allowing individuals in a group to recognize each other.

Gestation, of about 235 days, leads to the birth of a baby (rarely two) in water or on dry land. The female then isolates herself from the herd for a few weeks and defends her young against all attacks, especially from other hippopotamuses, especially males.

Essentially herbivorous, the hippopotamus can swallow up to 60 kg of food per day. It tears the grass with its lips, at ground level, and prefers creeping or stoloniferous grasses. He is very fond of crops of yams, potatoes, but fresh and vegetable crops, etc. Too high a density of animals can lead to severe degradation of vegetation and soil. The hippopotamus does not graze with its teeth but with its thick, hard-skinned lips. In the event of drought, hippos can even go without food for several weeks thanks to the thick layer of fat under their skin. They do not expend energy because they remain motionless in water or mud. It is a species that does not support polluted or dirty waters. This is the reason why, in general, the waters where hippos live are used as drinking water by rural populations.

This herbivore has few predators apart from the Lions for single animals; young people are sometimes prey to nile crocodile. Uncontrolled bush fires are a factor in the destruction of its habitat and food. Observations report the consumption of meat by hippopotamus, after having killed the animals (Impala in Zimbabwe) or concerning carrion, and even cannibalism.

The hippopotamus is very sensitive to light. The animal abhors noise and emptiness whereas music amuses it and attracts its curiosity. The animal becomes aggressive when injured. The low water level of the rivers, the drying up of ponds and rivers due to climate change lead to the migration of Hippos. During these migrations, these animals encounter enormous difficulties and even loss of life. In the wild, the longevity of the hippopotamus is about 40 years.

How to recognize a hippopotamus?

2 hippos fighting

2 hippos are fighting. © Pierre Poilecot

A hippopotamus can measure up to 4 m in length and weigh between 1.6 and 3.2 tonnes. The hippopotamus ranks among the megaherbivores (like the elephantthe black rhino and the GIRAFE). It appears as a huge, massive animal with short legs and a low belly. Unlike most mammals, the skin appears beardless; a few fine hairs exist on the back, sides and belly. The muzzle has long hard hairs. The skin is gray to chocolate brown in color, lighter and often pinkish on the neck, throat, belly and around the eyes. The epidermis can sometimes be darker, from brown to purplish red, due to a viscous glandular secretion (“blood sweat”) which protects it against desiccation due to the sun. This substance could also act as an antiseptic, a lubricant (to facilitate progress in the water) and, through its smell, allow a social bond between the animals. The short, flat tail is fringed at its tip with thick, stiff hair. The massive head, carried by a powerful neck, has a very wide muzzle and mouth, the jaws of which can open 180°. The eyes, small and prominent, are housed in large arches placed high on the skull. The nostrils are also prominent and located at the top of the rhinarium. The ears, small and inserted on the top of the skull, are fringed with hair at their end.

When the head is partially submerged, the nostrils, eyes and ears are above water. The limbs are short and massive, robust and end in four fingers with thick claws. The teeth of the hippopotamus are impressive and consist, in front of the mouth, of four highly developed canines, like tusks, and eight short, conical incisors. The canines, ridged along their entire length, can measure up to 60-70 cm at the level of the lower jaw (record 163.83 cm) and therefore constitute real weapons during fights between males. The incisors can reach 17 cm in length. The molars, contained behind the jaw, are used to grind plants. The hippopotamus has relatively well-developed senses, particularly hearing and smell. It utters various calls, including a sort of whinny or loud bellow associated with hissing and growling. The faeces are cylindrical dung 100-120 mm long and 80-100 mm in diameter, fibrous and blackish. They rarely have this initial shape because the animals disintegrate them by movements of the queue at the time of their emission.

Authors: Pierre POILECOT, Yemboado Georges NAMOANO and Jacob AGOSSEVI, p.our the Handbook of protected areas in French-speaking Africa (extract)

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