Historically, the Mountain Bongo occurred in and around forested zones of Mt. Kenya, the Aberdares, Mau forest, Cherengani hills and Chepalungu hills in Kenya and Mount Elgon in Kenya and Uganda (Elkan and Smith in press). The Mountain Bongo was exterminated from the Uganda side of Mount Elgon around 1913-1914 (Kingdon 1982). It is now confined to four completely isolated populations in patches of forest on Mt. Kenya, the Mau and Eburu forests, and the Aberdares in Kenya (Elkan and Smith in press).
Bongos predominantly inhabit the lowland forests of West Africa and Zaire to southern Sudan. Small populations reside in the montane or highland forest of Kenya and in the Congo.
Biogeographic Regions: ethiopian (Native )
Bongos are the largest and most colorful of the forest African antelopes. They exhibit sexual dimorphism; females weigh between 210 and 235 kilograms and the males range from 240 to 405 kilograms. Females and young are chestnut red, with darker legs. The males start out this chestnut color and proceed to darken with age, eventually becoming a dark brownish black. Both males and females have long spiraling horns (75-99cm) covered by a blackish brown keratinous sheath. The females' horns tend to be more parallel than the males and make about one spiral turn as opposed to the males' one and one half turns. Other notable features include large broad ears, white markings on the cheeks and legs, a white chevron between the eyes, and between 10 to 15 whitish-yellow stripes along the torso and rump.
Bongos tend to have shorter legs than other African antelopes and a body shape characteristic of forest ruminants. These characters help the large animal to move relatively fast in its dense forest habitat.
Range mass: 210 to 405 kg.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Habitat and Ecology
Bongos are predominantly found in the lowland forests of West Africa where they reside among the ground level shrubs and bushes. Smaller populations are often found in the montane forest regions of East Africa where they reside among the thick forest and bamboo zone. The habitat of this animal has a dual purpose. Bongos both feed and depend for cover on the bushes, herbs and bamboo found in these forested regions.
Terrestrial Biomes: rainforest ; scrub forest ; mountains
Bongos are grazers and browsers. They typically eat leaves, flowers, twigs, thistles, garden produce and cereals. Additionally, bongos favor younger leaves, suggesting that high protein and low fibre content influence their plant choice. Furthermore, bongos are known to regularly visit natural salt licks. In these salt lick areas they often graze, feeding on grasses and herbs. Bongos have also been known to eat burned wood as a means of getting salt or minerals. They use their long prehensile tongue for grasping leaves and their broad horns for pulling or breaking high branches.
Life History and Behavior
Perception Channels: tactile ; chemical
Status: captivity: 21.9 years.
Lifespan, longevity, and ageing
Bongos breed seasonally in the Aberdares; however, the mating patterns of the forest dwelling groups are poorly known due to the density of their habitat and their tendency to retreat during the daytime. It is however known that females come into estrus every 21 or 22 days and remain in estrus for approximately 3 days. During this period, the male follows the estrus female in a "low stretch" posture while emitting soft vocalizations. The male approaches the female, rubbing his head against her side and rump to test her for mounting receptivity. Before attempting the mount, the male assumes a "frozen" posture. After fertilization, the gestation period lasts from 282 to 285 days. The female gives birth to a single calf weighing approximately 19.5 kilograms. On rare occasion multiple births may occur in which two calves are born, in which case the birth weights are slightly less.
Range number of offspring: 1 (low) .
Average number of offspring: 1.
Range gestation period: 9.4 to 9.93 months.
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual
Average birth mass: 19800 g.
Average number of offspring: 1.
Average age at sexual or reproductive maturity (male)
Sex: male: 914 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 806 days.
Parental Investment: altricial ; precocial ; post-independence association with parents
Molecular Biology and Genetics
Barcode data: Tragelaphus eurycerus
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Tragelaphus eurycerus
Public Records: 2
Specimens with Barcodes: 2
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
- 1996Lower Risk/near threatened (LR/nt)
Habitat destruction, poaching and illelgal trapping are all factors that contribute to the decline of bongo populations in Africa. Projects to halt rainforest destruction and laws prohiting entrapment contribute to the conservation of the species.
US Federal List: no special status
CITES: appendix iii; no special status
IUCN Red List of Threatened Species: near threatened
The current population estimate (2007) for the Mountain Bongo is ca. 75-140 individuals: Aberdare Mts (50-100); Mt Kenya (6-12); Mau Forest (6-12), Eburu Forest (6-12) (M. Prettejohn and L. Estes in litt to ASG 2007).
Dense forest habitat, patchy distributions, wide-ranging patterns, retiring behaviour and crepuscular/nocturnal activity patterns hinder any reliable estimation of Bongo densities (Elkan and Smith in press). Hillman (1986) estimated 1.2/km in southern Sudan based on group size observations and mineral lick distribution.
Threats to Mountain Bongo include hunting with dogs and loss of habitat in the Mau and Eburu forests to illegal logging. The decline of Mountain Bongo populations in the Aberdares in recent years has been attributed to increased hunting by local people and habitat loss, and even to the increased numbers of Lion in the area (Elkan and Smith in press). Although these factors have no doubt contributed to the decline of Mountain Bongo, the impact of disease has probably been underestimated: the grazing of cattle in the forest reserves of Mount Kenya and the Aberdares as high as the Hagenia forest on the Aberdares plateau may have greater implications for Bongo conservation than hunting pressure in terms of disease transmission (L. Estes, in Elkan and Smith in press). Percival (1928) reported that rinderpest drastically reduced the populations of the Mountain Bongo in the 1890s, and populations are thought to have suffered greatly in later epidemics in the early 1900s.
East (1999) estimated that perhaps 60% of Bongo numbers were confined to protected areas. In Central Africa, these include Dzanga-Ndoki National Park and Bangassou areas of the Central African Republic, Lobeke National Park (Cameroon), and in Nouabale-Ndoki National Park and Odzala National Park (Republic of Congo); in West Africa, strongholds include Ta (Cte dIvoire), Sapo (Liberia), and Kakum National Parks (Ghana) (East 1999; Elkan and Smith in press). However, because the highest known abundances of Bongo in Central Africa occur in logging concessions not protected areas, an approach is needed that incorporates both protected areas and logging concessions (see Elkan 2003; Elkan and Smith in press).
The Mountain Bongos survival in the wild is dependent on more effective protection of the surviving remnant populations in Kenya (East 1999). Two conservation initiatives are currently in progress on Mountain Bongo. A programme to reintroduce Bongo to Mt Kenya began in 2004, when 18 animals where flown from North American zoos to a captive-breeding facility at Mount Kenya Game Ranch, on the north-western slope of the mountain. A second phase began in 2005, with the commencement of a research programme into the Mountain Bongos ecology. This project will attempt to determine the configuration of Bongo habitat on both the Aberdares and Mount Kenya, using recently collected field and remotely sensed data (L. Estes pers. comm.). Meanwhile, the Bongo Surveillance Programme, initiated in 2004, has been investigating the status of the remaining wild Bongo populations in Kenya (L. Estes pers. comm.).
Relevance to Humans and Ecosystems
Although these animals are difficult to shoot, they are rather easily hunted by dogs and hence provide a food source for African populations. Additionally, as browsers, bongos are important factors in keeping the vegetation of the forests from becoming overgrown. Since many other game animals depend on the health of this vegetation for food, this attribute secondarily affects humans.
Positive Impacts: food ; body parts are source of valuable material
|Subspecies:||T. eurycerus isaaci|
|Tragelaphus eurycerus isaaci|
|Mountain bongo range|
Bongos are characterised by a striking reddish-brown coat, black and white markings, white-yellow stripes and long slightly spiralled horns. Indeed, bongos are the only tragelaphid in which both sexes have horns. They have a complex social interaction and are found in African dense forest mosaics.
The eastern or mountain bongo, T. e. isaaci, of Kenya, has a coat even more vibrant than that of T. e. eurycerus. The mountain bongo is only found in the wild in one remote region of central Kenya. This bongo is classified by the IUCN Antelope Specialist Group as Critically Endangered, with more specimens in captivity than in the wild.
In 2000, the Association of Zoos and Aquariums in the USA (AZA) 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. However, in 2013, it seems, these successes have been negated with reports of possibly only 100 mountain bongos left in the wild due to logging and poaching.
The bongo belongs to the genus Tragelaphus, which includes the sitatunga (T. spekeii), the nyala (T. angasii), the bushbuck (T. scriptus), the mountain nyala (T. buxtoni), the lesser kudu (T. imberbis), and the greater kudu (T. strepsiceros).
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. They have been observed to live up to 19 years.
The generic name Tragelaphus is derived from the Greek words trago (a male goat) and elaphos (a deer), in combination referring to "an antelope". The specific name eurycerus originated from the fusion of eurus (broad, widespread) and keras (an animal's horn). "Bongo" is derived from a West African native name.
Distribution and habitat
Bongos are found in tropical jungles with dense undergrowth up to an altitude of 4,000 meters (12,800 ft) 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 Congo, the Ivory Coast, Equatorial Guinea, Gabon, Ghana, Guinea, Liberia, Sierra Leone, 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.
Adults of both sexes are similar in size. Adult height is about 1.1 to 1.3 m (3.6 to 4.3 ft) at the shoulder and length is 2.15 to 3.15 m (7.1 to 10.3 ft), including a tail of 45–65 cm (18–26 in). Females weigh around 150–235 kg (331–518 lb), while males weigh about 220–405 kg (485–893 lb). Its large size puts it as the third-largest in the Bovidae tribe of Strepsicerotini, behind both the common and greater elands by about 300 kg (660 lb), and above the greater kudu by about 40 kg (88 lb).
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. 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 makes which tend to be chestnut brown especially on the front part of their bodies.
The pigmentation in the coat rubs off quite easily; anecdotal reports suggest rain running off a bongo may be tinted red with pigment. 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, and vertical brown ridge of hair along the spine from the shoulder to the rump; the white stripes run into this ridge.
A white chevron appears between the eyes, and two large white spots grace each cheek. Another white chevron occurs where the neck meets the chest. The large ears are to sharpen hearing, and the distinctive coloration may help bongos identify one another in their dark forest habitats. Bongos have no special secretion glands, so rely less on scent to find one another than do other similar antelopes. The lips of a bongo are white, topped with a black muzzle.
Bongos have two heavy and slightly spiralled horns that slope over their backs, and like many other antelope species, both male and female bongos have horns. Bongos are the only tragelaphids in which both sexes have horns. The horns of bongos are in the form of a lyre and bear a resemblance to those of the related antelope species of nyalas, sitatungas, bushbucks, kudus and elands.
Unlike deer, which have branched antlers shed annually, bongos and other antelopes have pointed horns they keep throughout their lives. Males have massive backswept horns, while females have smaller, thinner, and more parallel horns. The size of the horns range between 75 and 99 cm (30–39 in). The horns twist once.
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 that makes up human fingernails, toenails. and hair. The bongo runs gracefully and at full speed through even the thickest tangles of lianas, laying its heavy spiralled horns on its back so the brush cannot impede its flight. Bongos are hunted for their horns by humans.
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 at six 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 serious fights take place. However, 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. 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 they find cover, they stay alert and face away from the disturbance, but peek every now and then 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, while newborn calves lie in hiding for a week or more, receiving short visits by the mother to suckle.
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 six months and reach sexual maturity at about 20 months.
Bongos require salt in their diets, and are known to regularly visit natural salt licks. Examination of bongo feces revealed the charcoal from trees burnt by lightning is consumed. 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. As a large animal, the bongo requires an ample amount of food, and is 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 327,000 km2, a total population estimate of around 28,000 is suggested. Only about 60% are in protected areas, suggesting 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 Mt. 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. Tragelaphus eurycerus may suffer from goitre. 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 coupled with 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); pythons sometimes eat bongo calves. Humans prey on them for their pelts, 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. However, these taboos are said no longer to exist, which may account for increased hunting by humans in recent times.
An international studbook is maintained to help manage animals held in captivity. Because of its bright colour, it is very popular in zoos and private collections. In North America, over 400 individuals are thought to be held, a population that probably exceeds that of the mountain bongo in the wild.
In 2000, the Association of Zoos and Aquariums (AZA) upgraded the bongo to a Species Survival Plan participant, which works to improve the genetic diversity of managed animal populations. The target population for participating zoos and private collections in North America is 250 animals. Through the efforts of zoos in North America, a reintroduction to the population in Kenya is being developed.
At least one collaborative effort for reintroduction between North American wildlife facilities has already been carried out. In 2004, 18 eastern bongos born in North American zoos gathered at White Oak Conservation in Yulee, Florida for release in Kenya. White Oak staff members traveled with the bongos to a Mt. Kenya holding facility, where they stayed until being reintroduced.
In the last few decades, a rapid decline in the numbers of wild mountain bongo has occurred due to poaching and human pressure on their habitat, with local extinctions reported in Cherangani and Chepalungu hills, Kenya.
The Bongo Surveillance Programme, working alongside the Kenya Wildlife Service, have recorded photos of bongos at remote salt licks in the Aberdare Forests using camera traps, and, by analyzing DNA extracted from dung, have confirmed the presence of bongo in Mount Kenya, Eburru and Mau forests. The programme estimate as few as 140 animals left in the wild – spread across four isolated populations. Whilst captive breeding programmes can be viewed as having been successful in ensuring survival of this species in Europe and North America, the situation in the wild has been less promising. Evidence exists of bongo surviving in Kenya. However, these populations are believed to be small, fragmented, and vulnerable to extinction.
Animal populations with impoverished genetic diversity are inherently less able to adapt to changes in their environments (such as climate change, disease outbreaks, habitat change, etc.). The isolation of the four remaining small bongo populations, which themselves would appear to be in decline, means a substantial amount of genetic material is lost each generation. Whilst the population remains small, the impact of transfers will be greater, so the establishment of a "metapopulation management plan" occurs concurrently with conservation initiatives to enhance in situ population growth, and this initiative is both urgent and fundamental to the future survival of mountain bongo in the wild.
The western/lowland bongo faces an ongoing population decline as habitat destruction and hunting pressures increase with the relentless expansion of human settlement. Its long-term survival will only be assured in areas which receive active protection and management. At present, such areas comprise about 30,000 km2, and several are in countries where political stability is fragile. So, a realistic possibility exists whereby its status could decline to Threatened in the near future.
As the largest and most spectacular forest antelope, the western/lowland bongo is both an important flagship species for protected areas such as national parks, and a major trophy species which has been taken in increasing numbers in Central Africa by sport hunters during the 1990s. Both of these factors are strong incentives to provide effective protection and management of populations.
Trophy hunting has the potential to provide economic justification for the preservation of larger areas of bongo habitat than national parks, especially in remote regions of Central Africa, where possibilities for commercially successful tourism are very limited.
The eastern/mountain bongo’s survival in the wild is dependent on more effective protection of the surviving remnant populations in Kenya. If this does not occur, it will eventually become extinct in the wild. The existence of a healthy captive population of this subspecies offers the potential for its reintroduction.
Groups supporting bongo conservation in Kenya
In 2004, Dr. Jake Veasey, the head of the Department of Animal Management and Conservation at Woburn Safari Park and a member of the European Association of Zoos and Aquariums Population Management Advisory Group, with the assistance of Lindsay Banks, took over responsibility for the management and coordination of the European Endangered Species Programme for the eastern bongo. This includes some 250 animals across Europe and the Middle East.
Along with the Rothschild giraffe, the eastern bongo is arguably one of the most threatened large mammals in Africa, with recent estimates numbering less than 140 animals, below a minimum sustainable viable population. The situation is exacerbated because these animals are spread across four isolated populations. Whilst the bongo endangered species program can be viewed as having been successful in ensuring survival of this species in Europe, it has not yet become actively involved in the conservation of this species in the wild in a coordinated fashion. The plan is to engage in conservation activities in Kenya to assist in reversing the decline of the eastern bongo populations and genetic diversity in Africa, and in particular, applying population management expertise to help ensure the persistence of genetic diversity in the free ranging wild populations.
To illustrate significance of genetic diversity loss, assume the average metapopulation size is 35 animals based on 140 animals spread across four populations (140/4=35). Assuming stable populations, these populations will lose 8% of their genetic diversity every decade. By managing all four populations as one, through strategic transfers, gene loss is reduced from 8% to 2% per decade, without any increase in bongo numbers in Kenya. By managing the European and African populations as one – by strategic exports from Europe combined with in situ transfers, gene loss is reduced to 0.72% every 100 years, with both populations remaining stable. If populations in Kenya are allowed to grow through the implementation of effective conservation, including strategic transfers, gene loss can be effectively halted in this species and its future secured in the wild.
The initial aims of the project are:
- Through faecal DNA analysis, estimate the genetic diversity of the remaining wild bongos and calculate the relatedness of the isolated wild populations.
- More accurately estimate the total population of wild bongos through faecal DNA analysis, camera trapping, and transect surveying.
- Through direct sampling, estimate the genetic diversity of the captive bongo population and calculate its relatedness with the remaining isolated wild populations.
- Collect DNA samples from western bongos to calculate the relatedness of the two subspecies.
- Fund rangers to collect the above data in Kenya, enhance the degree of protection afforded to and level of understanding of the eastern bongos' ecological needs.
- To realise such a metapopulation management plan, work with local communities is essential to reverse the decline and allow for the implementation of a transfer strategy. A substantial proportion of wild genetic diversity likely will have already have been lost.
If effective protection were implemented immediately and bongo populations allowed to expand without transfers, then this would create a bigger population of genetically impoverished bongos. These animals would be less able to adapt to a dynamic environment. Whilst the population remains small, the impact of transfers will be greater. For this reason, the 'metapopulation management plan' must occur concurrently with conservation strategies to enhance in situ population growth. This initiative is both urgent and fundamental to the future survival of the mountain bongo in the wild.
In 2013, SafariCom telecommunications donated money to the Bongo Surveillance Programme  to try and keep tabs on what is thought to be the last 100 eastern bongos left in the wild in the Mau Eburu Forest in central Kenya, whose numbers are still declining due to logging of their habitat and illegal poaching.
In 2002 the IUCN listed the western/lowland species as Near Threatened. These bongos may be endangered due to human environmental interaction, as well as hunting and illegal actions towards wildlife. CITES lists bongos as an Appendix III species, only regulating their exportation from a single country, Ghana. It is not protected by the US Endangered Species Act and is not listed by the USFWS.
The IUCN Antelope Specialist Group considers the western or lowland bongo, T. e. eurycerus, to be Lower Risk (Near Threatened), and the eastern or mountain bongo, T. e. isaaci, of Kenya, to be Critically Endangered. Other subspecific names have been used, but their validity has not been tested.
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- Bongo Surveillance Programme monitoring and surveillance continues in Aberdare, Mt. kenya, Eburru and South West Mau. mountainbongo.org
- Kenya's Mountain Bongo antelope under threat. BBC News. 18 April 2013