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Tragelaphus eurycerusbongo

By Julie Brensike

Geographic Range

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.

Habitat

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.

Physical Description

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.

  • Sexual Dimorphism
  • male larger
  • Range mass
    210 to 405 kg
    462.56 to 892.07 lb

Reproduction

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.

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • Range number of offspring
    1 (low)
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Range gestation period
    9.4 to 9.93 months
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    806 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    914 days
    AnAge

Lifespan/Longevity

  • Average lifespan
    Status: captivity
    21.9 years
    AnAge

Behavior

Bongos are the only forest antelope to form herds. These herds range anywhere from 5 or 6 bongos foraging for food together, all the way up to 50. More than one male was included in a number of the herds seen, indicating that bongos are fairly non-territorial. These animals are both diurnal and nocturnal. They stay within the bushes and shrubs of the forest during the day and only come out to the salt licks during the night. They tend to stay out of sight, and it is for this reason that the behavior of bongos has been difficult to study. Relatively little else is known about the activities of these reclusive creatures.

Communication and Perception

Food Habits

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.

Economic Importance for Humans: Positive

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

Economic Importance for Humans: Negative

None

Conservation Status

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.

Other Comments

Bongos are unusual in the genus Tragelaphus in that both sexes have horns. Only one other species, T. oryx, shares this trait. The name Tragelaphus eurycerus comes from the Greek words tragos, meaning "goat," elaphos, meaning "deer," eurys, meaning "broad/widespread," and keras, meaning "horns."

Contributors

Julie Brensike (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

food

A substance that provides both nutrients and energy to a living thing.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scrub forest

scrub forests develop in areas that experience dry seasons.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

solitary

lives alone

tactile

uses touch to communicate

young precocial

young are relatively well-developed when born

References

10/98. "Animal Bytes" (On-line). Accessed 10/13/99 at http://www.seaworld.org/animal_bytes/bongoab.html.

Jewell, P., G. Maloiy. 1989. The Biology of Large African Mammals in Their Environment. Oxford, England: Oxford Science Publications.

Klaus-Hugi, C., G. Klaus, B. Schmid, B. Konig. 1998. Feeding ecology of a large social antelope in the rainforest. Oecologia, 119: 81-90.

Ralls, K. 1978. Tragelaphus eurycerus. Mammalian Species, 111: 1-4.

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