The bongo (Tragelaphus eurycerus) is a large, mostly nocturnal, forest-dwelling antelope, native to sub-Saharan Africa. Bongos are characterised by a striking reddish-brown coat, black-and-white markings, white-yellow stripes, and long, slightly spiraled horns. Bongos have complex social interactions and are found in African dense forest mosaics. They are the third-largest antelope in the world.
In 2000, the Association of Zoos and Aquariums in the US upgraded the bongo to a Species Survival Plan participant and in 2006 added the Bongo Restoration to Mount Kenya Project to its list of the Top Ten Wildlife Conservation Success Stories of the year. , these successes have been compromised by reports of possibly only 100 mountain bongos left in the wild due to logging and poaching.
Taxonomy
The scientific name of the bongo is Tragelaphus eurycerus, and it belongs to the family Bovidae. It was first described by Irish naturalist William Ogilby in 1837. The generic name Tragelaphus is composed of two Greek words: trag-, meaning a goat; and elaphos, meaning deer. The specific name eurycerus originated from the fusion of eurus (broad, widespread) and keras (an animal's horn). The common name "bongo" originated probably from the Kele language of Gabon. The first known use of the name "bongo" in English dates to 1861.
Bongos are further classified into two subspecies: T. e. eurycerus, the lowland or western bongo, and the far rarer T. e. isaaci, the mountain or eastern bongo, restricted to the mountains of Kenya only. The eastern bongo is larger and heavier than the western bongo. Two other subspecies are described from West and Central Africa, but taxonomic clarification is required.
The western or 'lowland bongo, T. e. eurycerus, faces an ongoing population decline, and the IUCN Antelope Specialist Group considers it to be near threatened on the conservation status scale.
The eastern or mountain bongo, T. e. isaaci, of Kenya has a coat even more vibrant than that of T. e. eurycerus. It is only found in the wild in a few mountain regions of central Kenya. This bongo is classified by the IUCN Antelope Specialist Group as critically endangered, with fewer individuals in the wild than in captivity (where it breeds readily).
Appearance Bongos are one of the largest of the forest antelopes. In addition to the deep chestnut colour of their coats, they have bright white stripes on their sides to help with camouflage.
Adults of both sexes are similar in size. Adult height is about at the shoulder and length is , including a tail of . Females weigh around , while males weigh about . Its large size puts it as the third-largest in the Bovidae tribe of Strepsicerotini, behind both the common and greater eland by about , and above the greater kudu by about .
Both sexes have heavy, spiral horns; those of the male are longer and more massive. All bongos in captivity are from the isolated Aberdare Mountains of central Kenya.
Coat and body
The bongo sports a bright auburn or chestnut coat, with the neck, chest, and legs generally darker than the rest of the body, especially in males. Coats of male bongos become darker as they age until they reach a dark mahogany-brown colour. Coats of female bongos are usually more brightly coloured than those of males. The eastern bongo is darker in color than the western, and this is especially pronounced in older males, which tend to be chestnut brown, especially on the forepart of their bodies.
The smooth coat is marked with 10–15 vertical, white-yellow stripes, spread along the back from the base of the neck to the rump. The number of stripes on each side is rarely the same. It also has a short, bristly, brown ridge of dorsal hair from the shoulder to the rump; the white stripes run into this ridge.
A white chevron appears between the eyes, with two large, white spots on each cheek. Another white chevron occurs where the neck meets the chest. Bongos have no special secretion glands, so rely likely less on scent to find one another than do other similar antelopes. The lips of a bongo are white, topped with a black muzzle.
Horns
Bongos have two heavy and slightly spiraled horns that slope over their backs. Males have larger, backswept horns, while females have smaller, thinner, and more parallel horns. The sizes of the horns range between . Their spiraled horn trait is shared with the related antelope species of nyalas, sitatungas, bushbucks, kudus, and elands. The horns of bongos twist once.
Unlike deer, which have branched antlers they shed annually, bongos and other antelopes have unbranched horns they keep throughout their lives.
Like all other horns of antelopes, the core of a bongo's horn is hollow, and the outer layer of the horn is made of keratin, the same material in human fingernails, toenails, and hair. The bongo runs gracefully and at full speed through even the thickest tangles of lianas, laying its horns on its back so the brush cannot impede its flight. Bongos are hunted for their horns by humans.Walther, F. R. (1990) "Spiral-horned antelopes". In Grzimek's Encyclopedia of Mammals. S. P. Parker (ed.). New York: McGraw-Hill. Volume 5, pp. 344–359.
Social organization and behavior
Like other forest ungulates, bongos are seldom seen in large groups. Males, called bulls, tend to be solitary, while females with young live in groups of six to eight. Bongos have seldom been seen in herds of more than 20. Gestation is about 285 days (9.5 months), with one young per birth, and weaning occurs around 6 months. Sexual maturity is reached at 24–27 months. The preferred habitat of this species is so dense and difficult to operate in that few Europeans or Americans observed this species until the 1960s. As young males mature and leave their maternal groups, they most often remain solitary, although rarely they join an older male. Adult males of similar size/age tend to avoid one another. Occasionally, they meet and spar with their horns in a ritualised manner, and rarely do serious fights take place. Such fights are usually discouraged by visual displays, in which the males bulge their necks, roll their eyes, and hold their horns in a vertical position while slowly pacing back and forth in front of the other male. They seek out females only during mating time.Estes, Richard D. (1991) The Behavior Guide to African Mammals: Including Hoofed Mammals, Carnivores, Primates. Berkeley and Los Angeles: University of California Press. When they are with a herd of females, males do not coerce them or try to restrict their movements as do some other antelopes.
Although mostly nocturnal, they are occasionally active during the day. However, like deer, bongos may exhibit crepuscular behaviour. Bongos are both timid and easily frightened; after a scare, a bongo moves away at considerable speed, even through dense undergrowth. Once it finds cover,it stays alert and faces away from the disturbance, but peeks occasionally to check the situation. The bongo's hindquarters are less conspicuous than the forequarters, and from this position, the animal can quickly flee.
When in distress, the bongo emits a bleat. It uses a limited number of vocalisations, mostly grunts and snorts; females have a weak mooing contact-call for their young. Females prefer to use traditional calving grounds restricted to certain areas, where newborn calves lie in hiding for a week or more, receiving short visits by the mother to suckle.Estes, Richard (1993) The Safari Companion. Vermont: Chelsea Green Publishing Co.
The calves grow rapidly and can soon accompany their mothers in the nursery herds. Their horns grow rapidly and begin to show in 3.5 months. They are weaned after 6 months and reach sexual maturity around 20 months. They have been observed to live up to 19 years.Spinage, C.A. (1986) The Natural History of Antelopes. New York: Facts on File Publications.
Ecology Distribution and habitat Bongos are found in tropical jungles with dense undergrowth up to an altitude of in Central Africa, with isolated populations in Kenya, and these West African countries: Cameroon, the Central African Republic, the Republic of the Congo, the Democratic Republic of the Congo, Ivory Coast, Equatorial Guinea, Gabon, Ghana, Guinea, Liberia, Sierra Leone, and South Sudan.
Historically, bongos are found in three disjunct parts of Africa: East, Central, and West. Today, all three populations' ranges have shrunk in size due to habitat loss for agriculture and uncontrolled timber cutting, as well as hunting for meat.
Bongos favour disturbed forest mosaics that provide fresh, low-level, green vegetation. Such habitats may be promoted by heavy browsing by elephants, fires, flooding, tree-felling (natural or by logging), and fallowing. Mass bamboo die-off provides ideal habitat in East Africa. They can live in bamboo forests.
Diet
Like many forest ungulates, bongos are herbivorous browsers and feed on leaves, bushes, vines, bark and pith of rotting trees, grasses/herbs, roots, cereals, and fruits.
Bongos require salt in their diets and are known to visit natural salt licks regularly. They also are known to eat burnt wood after a storm, a rich source of salt and minerals. This behavior is believed to be a means of getting salts and minerals into their diets. This behavior has also been reported in the okapi. Another similarity to the okapi, though the bongo is unrelated, is that the bongo has a long, prehensile tongue, which it uses to grasp grasses and leaves.
Suitable habitats for bongos must have permanent water available.Nowak, Ronald (1991) M. Walker's Mammals of the World 5th ed. Vol. II. Baltimore: The Johns Hopkins University Press As a large animal, they are restricted to areas with abundant year-round growth of herbs and low shrubs.
Population and conservation Few estimates of population density are available. Assuming average population densities of 0.25 animals per km2 in regions where it is known to be common or abundant, and 0.02 per km2 elsewhere, and with a total area of occupancy of , a total population estimate around 28,000 is suggested. Only about 60% are in protected areas, so the actual numbers of the lowland subspecies may only be in the low tens of thousands. In Kenya, their numbers have declined significantly, and on Mount Kenya, they were extirpated within the last decade due to illegal hunting with dogs. Although information on their status in the wild is lacking, lowland bongos are not presently considered endangered.
Bongos are susceptible to diseases such as rinderpest, which almost exterminated the species during the 1890s. T. eurycerus may suffer from goiter. Over the course of the disease, the thyroid glands greatly enlarge (up to 10 x 20 cm) and may become polycystic. Pathogenesis of goiter in the bongo may reflect a mixture of genetic predisposition and environmental factors, including a period of exposure to a goitrogen. Leopards and spotted hyenas are the primary natural predators (lions are seldom encountered due to differing habitat preferences); Central African rock pythons sometimes eat bongo calves. Humans prey on them for their hides, horns, and meat, with the species being a common local source for "bush meat". Bongo populations have been greatly reduced by hunting, poaching, and animal trapping, although some bongo refuges exist.
Although bongos are quite easy for humans to catch using snares, many people native to the bongos' habitat believed that if they ate or touched bongo, they would have spasms similar to epileptic seizures. Because of this superstition, bongos were less harmed in their native ranges than expected, but these taboos are said to no longer to exist, which may account for increased hunting by humans in recent times.
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