Hippo

Hippos - River Horse of Africa

Known as "river horses" to the ancient Greeks and "sea cows" (seekoi) to the Dutch settlers, the hippo is not related to either. It is, in fact, a distant relative of the pigs, although its ancestry is not well understood. Weighing up to 3 200kg, the hippo is the third heaviest African land mammal, after the elephant and white rhinoceros. With tiny eyes, ears and nostrils all placed on the very top of the head, they are superbly adapted for an amphibious lifestyle.

The hippo once occupied almost every river system in Africa, from the southern Cape wetlands to the Nile Delta in Egypt, but due to hunting pressure, it is now largely restricted to protected or inaccessible areas south of the Sahara. Hippos require deep water in which to submerge their bulky bodies and a supply of short grass on which to feed. Their skin lacks sweat glands, so hippos are prone to dehydration and it is critical that they avoid direct sunshine by spending most of the day in water or mud, although they will sometimes bask in the sun for short periods.

Nocturnal Feeders

At sunset, hippos typically leave their aquatic refuge and wander down well-trod pathways to favoured feeding grounds. Flat areas colonised by creeping grasses such as Cynodon are favoured, and a resident population soon creates a lawn-like landscape. Individuals consume up to 60kg of grass per night. Their broad leathery lips are ideal for cropping the grass short but do not damage the roots, and other grazing herbivores such as zebra and warthog benefit from the constant regrowth of fresh grass shoots. An overpopulation of hippo can, however, lead to the encroachment of woody vegetation as a lack of grass eliminates the chance of restorative grass fires.

In recent years, there have been a number of eye-witness accounts of hippos tearing up the flesh of drowned animals or the remains of predator kills, and this has led to the belief that they occasionally stray from their vegetarian diet. Documentation of the actual swallowing of flesh is still lacking, however, and it is possible that the observed hippos were trying to feed on the rumen content of the dead herbivores rather than on their flesh. In the dry season when available grass is in short supply, it is not uncommon to see them feeding on the coarse droppings of elephants.

Social Habits

Hippos have a hierarchical society in which individuals constantly display their status to one another. Adult females with their successive offspring form the foundation of social units which occupy a home range, while the largest adult male holds dominance in a restricted range in which he defends exclusive mating rights. Fierce and bloody clashes between rival males are commonplace, but subordinate (non-challenging) males are tolerated by dominant bulls.

Groups tend to be sedentary during the dry season but move far and wide during the wet season when smaller pools become available. Hippos are extremely vocal when in water (but silent on land), as individuals wheeze, honk and blow air from their nostrils. Calling of any kind seems to be contagious, and noisy bouts of honking and wheezing are made in response to disturbances, or when returning to the water after a night of feeding.

Suckling Underwater

A single youngster - very rarely twins - is born after an eight month gestation, with the mother moving away from the social group with her new offspring for about two weeks after birth. The baby is born in shallow water or on dry land, but is adapted to swim immediately and suckles while completely submerged. The youngsters are quite playful for the first year of life and are usually weaned at about eight months. Births are usually spaced at two year intervals, and up to four successive calves may accompany their mother before the eldest becomes independent. Females become sexually mature at between seven and fifteen years, and probably live to about 35 under normal circumstances (captive hippo have lived for up to 50 years).

Small Cousin of the Rainforest

The pygmy hippo is critically endangered in its limited range, with probably less than 1000 surviving in isolated patches of rainforest in Nigeria, Ivory Coast and Liberia. Just about one tenth of the weight of an adult common hippo, the pygmy hippo has declined due to extensive deforestation of its habitat, as well as rampant hunting. An intensive captive breeding program would be required in any conservation plan.

CCAfrica Lodges with Excellent Hippo Sightings

Superb hippo viewing exists at Grumeti Serengeti Tented Camp in the Western Corridor of the Serengeti in Tanzania. There is also good viewing in the Mara River close to Kichwa Tembo in Kenya, where the vociferous animals greatly add to the wild atmosphere. The Zambezi River and Okavango Delta provide ideal hippo habitat, providing guests at Matetsi Game Lodges in Zimbabwe and Botswana's Nxabega Okavango Safari Camp and Sandibe Okavango Safari Lodge with excellent sightings.

Hippo are also present on the floor of the Ngorongoro Crater in Tanzania and in Lake Manyara. In South Africa, small numbers of hippo can be seen at Tau Game Lodge, Londolozi Private Game Reserve, Ngala Game Lodge and Phinda Private Game Reserve where they occupy dams.

Posted: Mammals by CC Africa, Date: 21 November 2006