| Bongo | |
|---|---|
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| A western/lowland bongo at theMarwell Zoo inHampshire,England | |
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| An eastern/mountain bongo at theJacksonville Zoo inJacksonville,Florida | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Artiodactyla |
| Family: | Bovidae |
| Subfamily: | Bovinae |
| Genus: | Tragelaphus |
| Species: | T. eurycerus |
| Binomial name | |
| Tragelaphus eurycerus (Ogilby, 1837) | |
| Subspecies | |
| |
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| Lowland bongo range | |
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| Mountain bongo range | |
Thebongo (Tragelaphus eurycerus) is a large, mostlynocturnal,forest-dwellingantelope,native tosub-Saharan Africa. Bongos are characterised by a striking reddish-brown coat, black and white markings, white-yellow stripes, and long slightly spiralled horns. It is the onlytragelaphid in which both sexes have horns. Bongos have complex social interactions and are found in African dense forest mosaics. They are the third-largest antelope in the world.[3]
Thewestern orlowland bongo,T. e. eurycerus, faces an ongoing population decline, and theIUCN Antelope Specialist Group considers it to beNear Threatened on theconservation status scale.[2]
Theeastern or mountain bongo,T. e. isaaci, ofKenya, has a coat even more vibrant than that ofT. e. eurycerus. The mountain bongo is only found in the wild in a few mountain regions of central Kenya. This bongo is classified by the IUCN Antelope Specialist Group asCritically Endangered, with fewer individuals in the wild than in captivity (where it breeds readily).[4]
In 2000, theAssociation of Zoos and Aquariums in the US (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. As of 2013[update], these successes have been compromised by reports of possibly only 100 mountain bongos left in the wild due tologging andpoaching.
| Phylogenetic relationships of the mountain nyala from combined analysis of all molecular data (Willows-Munro et.al. 2005) |
Thescientific name of the bongo isTragelaphus eurycerus, and it belongs to thegenusTragelaphus andfamilyBovidae. It was first described by Irish naturalistWilliam Ogilby in 1837.[5] Thegeneric nameTragelaphus is composed of two Greek words:trag-, meaning a goat; andelaphos, meaning deer.[6] Thespecific nameeurycerus originated from the fusion ofeurus (broad, widespread) andkeras (an animal's horn).[7] The common name "bongo" originated probably from theKele language ofGabon. The first known use of the name "bongo" in English dates to 1861.[8]
Bongos are further classified into twosubspecies:T. e. eurycerus, the lowland or western bongo, and the far rarerT. 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.[9]
Bongos are one of the largest of the forest antelopes. In addition to the deepchestnut colour of their coats, they have bright white stripes on their sides to help withcamouflage.
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 thecommon andgreater eland by about 300 kg (660 lb), and above thegreater kudu by about 40 kg (88 lb).[10][11]
Both sexes have heavy spiral horns; those of the male are longer and more massive. All bongos in captivity are from the isolatedAberdare Mountains of centralKenya.
The bongo sports a brightauburn 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 darkmahogany-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.
Bongos have two heavy and slightly spiralledhorns that slope over their backs. Bongo males have larger backswept horns, while females have smaller, thinner, and more parallel horns. The size of the horns range between 75 and 99 cm (29.5 and 39 in). The horns of bongos are spiraled, and share this trait with those of the related antelope species ofnyalas,sitatungas,bushbucks,kudus, andelands. The horns of bongos twist once.
Unlikedeer, which have branchedantlers 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 ofkeratin, the same material that makes up human fingernails, toenails, and hair. The bongo runs gracefully and at full speed through even the thickest tangles oflianas, laying its heavy spiralled horns on its back so the brush cannot impede its flight. Bongos are hunted for their horns by humans.[12]
Like other forestungulates, 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, andweaning 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 it is rare for serious fights to 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.[13] 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 mostlynocturnal, they are occasionally active during the day. However, like deer, bongos may exhibitcrepuscular behaviour.[14] 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.[9] 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 ableat. 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 traditionalcalving grounds restricted to certain areas, where newborn calves lie in hiding for a week or more, receiving short visits by the mother tosuckle.[15]
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 are found intropical jungles with dense undergrowth up to an altitude of 4,000 m (13,000 ft) in Central Africa, with isolated populations inKenya, and these West African countries:Cameroon, theCentral African Republic, theRepublic of the Congo, theDemocratic Republic of the Congo, theIvory Coast,Equatorial Guinea,Gabon,Ghana,Guinea,Liberia,Sierra Leone, andSouth 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), andfallowing. Massbamboo die-off provides ideal habitat in East Africa. They can live in bamboo forests.
Like many forestungulates, bongos areherbivorous 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 regularly visit natural salt licks. Bongos are also known to eat burnt wood after a storm, a rich source of salt and minerals.[16][17] This behavior is believed to be a means of getting salts andminerals into their diets. This behavior has also been reported in theokapi. Another similarity to the okapi, though the bongo is unrelated, is that the bongo has a longprehensile tongue which it uses to grasp grasses and leaves.
Suitable habitats for bongos must have permanent water available.[18] 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.
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 (126,000 sq mi), 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 onMount Kenya, they wereextirpated 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 asrinderpest, which almost exterminated the species during the 1890s.Tragelaphus eurycerus may suffer fromgoitre. Over the course of the disease, thethyroid glands greatly enlarge (up to 10 x 20 cm) and may becomepolycystic. Pathogenesis of goiter in the bongo may reflect a mixture of genetic predisposition coupled with environmental factors, including a period of exposure to agoitrogen.[19]Leopards andspotted 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 theirpelts, horns, and meat, with the species being a common local source for "bush meat".[5] Bongo populations have been greatly reduced by hunting,poaching, andanimal 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 toepileptic seizures. Because of thissuperstition, bongos were less harmed in their native ranges than expected. However, these taboos are said to 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, theAssociation of Zoos and Aquariums (AZA) upgraded the bongo to a Species Survival Plan participant, which works to improve thegenetic 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 atWhite Oak Conservation inYulee, Florida, for release in Kenya. White Oak staff members traveled with the bongos to a Mount Kenya holding facility, where they stayed until being reintroduced.[20]
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 inCherang'any andChepalungu hills, Kenya.
The Bongo Surveillance Programme, working alongside theKenya Wildlife Service, have recorded photos of bongos at remote salt licks in the Aberdare Forests using camera traps, and, by analyzingDNA extracted fromdung, have confirmed the presence of bongo in Mount Kenya,Eburru, andMau 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 enhancein 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 ashabitat 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. Therefore, 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.[21] Both of these factors are strong incentives to provide effective protection and management of populations.[22]
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.[21]
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.[1]
In 2004, Dr. Jake Veasey, the head of the Department of Animal Management and Conservation atWoburn 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 theEuropean Endangered Species Programme for the eastern bongo. This includes some 250 animals across Europe and the Middle East.
Along with theRothschild's 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 within 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:
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 enhancein 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[23] to try to keep tabs on what are 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.[24]
Mount Kenya Wildlife Conservancy runs a bongo rehabilitation program in collaboration with the Kenya Wildlife Service.[25] The Conservancy aims to prevent extinction of the bongo through breeding and release back into the wild.[26][27]
The IUCN Antelope Specialist Group considers the western or lowland bongo,T. e. eurycerus, to be Lower Risk (Near Threatened)[2] and the eastern or mountain bongo,T. e. isaaci, of Kenya, to beCritically Endangered.[4] 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.[citation needed] It is not protected by theUS Endangered Species Act and is not listed by theUSFWS.
