Waterbuck

The waterbuck is a large antelope found widely in sub-Saharan Africa, with a brown to grey coat and, in males only, long spiral horns that curve backward and then forward. It is mostly a grazer and lives on grassland, scrub and savanna near rivers, lakes and valleys, since it cannot tolerate dehydration in hot weather. Waterbucks are gregarious, forming herds of six to thirty that are either nursery herds of females and offspring or bachelor herds. Males show territorial behaviour from the age of five years and are most dominant between six and nine. Gestation lasts 7-8 months and ends in a single calf.

About the waterbuck

The waterbuck is a large, shaggy antelope of sub-Saharan Africa and the biggest of the six species in the genus Kobus, which also includes the kob and the puku. It belongs to the family Bovidae and lives in scrub and savanna close to rivers, lakes and valleys.

It is a heavy, robustly built animal with a long neck and short, strong black legs. Males stand about 127 cm (50 in) at the shoulder and females about 119 cm (47 in), and the waterbuck ranks among the heaviest antelopes. A newborn calf weighs around 13.6 kg (30 lb). The tail is 22–45 cm (8.7–17.7 in) long.

The coat runs from reddish brown to gray and darkens with age, and males are darker than females. It looks thick, but the hair on the body is actually sparse; only the neck carries long, shaggy hair. The face has a white muzzle, pale eyebrows and pale inner ears, and a cream-colored "bib" marks the throat.

When sexually excited, the skin produces a greasy secretion with a musky smell, which earned the animal the nickname "greasy kob." The odor is unpleasant enough to deter predators, and the oil also helps waterproof the body when the animal goes into water. Unlike many antelopes, the waterbuck has no glands in front of the eyes, on the feet or in the groin.

Only males grow horns. They are long and spiraled, sweeping backward and then forward, and measure 55–99 cm (22–39 in), with length partly tied to age. Females may have only a small bony lump where a horn would be. The species name, Kobus ellipsiprymnus, refers to the white elliptical ring on the rump, from Greek words for "ellipse" and "hind part." The common name reflects how heavily the animal depends on water and its habit of escaping into it.

Behavior and diet

Waterbuck are fairly sedentary, though some move with the onset of the rains. They live in herds of six to 30, split into nursery herds of females and young, bachelor herds of young males, and territorial bulls. Herds grow larger in summer and break up in winter, probably in response to food supply. Females use home ranges of 200–600 hectares (490–1,480 acres).

When young males begin to grow horns at seven to nine months old, territorial bulls drive them out of the herd. Males start acting territorial at about five years and are most dominant between six and nine. Territories range from 4 to 146 hectares (about 10 to 360 acres). A territory holder may tolerate a few "satellite" males, mature bulls without territories of their own, who help defend it but can eventually take it over. After about age ten, bulls lose their territories to younger males. In one study at Lake Nakuru, only 7 percent of adult males held a territory.

Displays show off the white throat patch and the thickness of the neck. A challenger signals submission by lowering its head and body. Fights include snorting and threat displays and can last up to 30 minutes; some end with one bull killed by wounds to the chest or belly. Waterbuck are mostly quiet animals, communicating through alarm snorts and the lip-curling flehmen response.

Predators include lions, spotted hyenas, leopards, cheetahs, African wild dogs and Nile crocodiles; leopards and hyenas mainly take young animals. Waterbuck often run into water or cover to escape, although they don't seem to enjoy being in water, and males will attack predators.

What waterbuck eat

The waterbuck is mainly a grazer. Grasses make up 70 to 95 percent of its diet, and it also eats reeds and rushes such as Typha and Phragmites. In the dry season, perennial grasses and leaves from trees make up three-quarters of what it eats, and about 32 percent of the day may be spent browsing; in the wet season it hardly browses at all. Grass choice changes from place to place rather than simply following what's available.

What sets it apart is its need for water. A waterbuck cannot tolerate dehydration in hot weather, so it always stays close to a water source, even when it ranges into woodland farther than its kob and puku relatives do.

Reproduction

Waterbuck mature slowly for antelopes. Females can conceive at about two and a half years and stay reproductive for roughly ten more years, while males become sexually mature at about six. Near the equator, breeding happens all year with a peak of births in the rainy season. In other places, such as south of the Sahara in Sudan, mating is confined to a four-month season.

Gestation takes seven to eight months, and a single calf is the rule; twins are rare. The mother goes off alone into thick cover to give birth, and the calf can stand within half an hour. Calves stay hidden for anywhere from two or three weeks up to two months, then start following their mothers at three to four weeks old when she raises her tail as a signal. Mothers defend calves fiercely despite having no horns. Calves are weaned at about eight months.

Range and habitat

The waterbuck lives across much of sub-Saharan Africa. It is found in southern and eastern countries such as Angola, Botswana, the Democratic Republic of the Congo, Ethiopia, Kenya, Namibia, South Africa, Tanzania and Uganda, and in parts of western and northern Africa including Chad, Côte d'Ivoire, Ghana, Mali, Niger, Nigeria and Senegal. It was once widespread but has declined in most areas.

The common waterbuck lives east of the East African Rift, reaching south to KwaZulu-Natal and central Namibia. The defassa waterbuck lives in western and central Africa, west of the Albertine Rift, from Eritrea to Guinea-Bissau and as far north as southern Mali. The common form is now extinct in Ethiopia, and the defassa form has disappeared from Gambia.

Habitat is scrub and savanna along rivers, lakes and valleys. Because it needs both grassland and water, the waterbuck is patchily distributed along the edges where those habitats meet. Densities can be low: 5.5 animals per square mile (about 2.1 per km²) in one study in the Ruwenzori range, and as few as 1.3 per square mile (about 0.5 per km²) in the Maasai Mara.

Common waterbuck vs defassa waterbuck

The species is split into two groups that were once treated as separate species. They interbreed where their ranges overlap, as in Nairobi National Park, so they are now considered one species. The easiest way to tell them apart is the rump.

Conservation status

The waterbuck as a whole is listed as Least Concern, last assessed in 2016. The two groups are assessed differently: the common waterbuck is Least Concern, while the defassa waterbuck is Near Threatened. Both are decreasing, the defassa especially.

The main threats are poaching and human settlement, which have wiped out large populations from some areas, and the animal's sedentary habits make it more vulnerable. Numbers have fallen in several national parks, including Queen Elizabeth, Murchison Falls, Akagera, Lake Nakuru and Comoé. At Lake Nakuru, the decline was linked to heavy-metal poisoning, with dangerous levels of cadmium and lead found in the animals' kidneys and livers. More than 60 percent of defassa waterbuck live in protected areas.

The waterbuck also has a practical use. Its body odor repels tsetse flies, and researchers have developed tsetse-repellent collars for cattle based on its smell.