BONGO, Tragelaphus (Boocercus) eurycerus

Tragelaphus eurycerus isaaci
Tragelaphus eurycerus eurycerus

BONGO
Tragelaphus eurycerws

WHAT IT IS

The biggest, most colorful and sociable forest antelope. Built like a heavyweight bushbuck. Male wt 528-891 lb (240-405 kg), ht 44-54 in (110-130 cm);Female wt 462-557 lb (210-253 kg), ht slightly shorter. Head: wide, with enormous ears. Horns: 1 turn, 30 in (75 cm) up to 39 in (99 cm). Male's massive; female's thinner and more parallel. Tail: hock-length, with terminal tuft. Coat: smooth and glossy. Color females and young bright chestnut above, darker below; males darken with age to blackish brown. Vivid white-yellow markings include 12 to 14 torso stripes, chest crescent, cheek patches, ear edging, and nose chevron. Legs banded black and white.

WHERE IT LIVES

Lowland Rainforest of West Africa and Zaire east to southern Sudan, and isolated populations in montane forests of Kenya.

GOOD PLACES TO SEE IT

Aberdare NP and Forest Reserve, Kenya.

ECOLOGY

Ground-level herbage in the rainforest exists only in forest clearings and secondary growth, which is where bongos are found. In the mountains, they frequent the cloud forest and bamboo zone. Bushes, herbs, creepers, and bamboo provide both cover and food. Browses the most nutritious leaves, flowers, and twigs of various shrubs and vines, thistles, and succulents, also cereals and garden produce. Uses its long, mobile tongue to rasp and bundle leaves and its horns to pull down and break hard to reach branches.

ACTIVITY

Night and day. Although guests at Aberdare lodges see bongos which visit water holes and salt licks mainly at night, this proves only that they are night-active. Bongos may simply feel uncomfortable in the open by day. They move about in cover and feed early and late in the day, resting in thickets between 10:30 AM and 4 PM, longer in bad weather.

SOCIAL/MATING SYSTEM

A few related females that associate over a long time, casually joining and separating from other females and their offspring, may be the basic units in bongo society. The mean number of bongos observed drinking and eating salt at The Ark in the Aberdare Forest is just 2, and herds of over a dozen are considered large. Herds of over 5 or 6 animals usually include calves and smaller herds contain only adults (in southern Sudan). The biggest Aberdare herds (up to 50) are seen after the calving season, when mothers and young band together in herds of 9 or more-perhaps on the calves' initiative (see eland account).
Lasting associations between known cows, frequent aggressive interactions, and social licking all suggest a regular rank hierarchy. Also, senior cows seem to play leadership roles, appearing alone to check out a water hole, leaving and then returning with a herd in tow. Home range size may be over 39 sq.mi. (100 km2) in the Aberdares, where bongos move up and down the mountain with changing seasons.
Adult male bongos are often solitary. Yet 1/3 of herds observed in Sudan that contained adults of both sexes included 2 or more adult bulls. During the mating peak in the Aberdares (Oct.-Jan.), though, usually a lone black bull accompanies or trails female herds.

HOW IT MOVES

The bongo's thick body, massive hindquarters, and short legs are designed for movement through dense vegetation. It is also an accomplished high-jumper. A clumsy, short-winded runner in the open, it skulks away silently in cover, or bolts suddenly from hiding, with nose out and horns laid back.

REPRODUCTION

Bongos in the Aberdares are known to breed seasonally, but nothing is known about populations living in its main lowland-forest range. A captive female that came into heat at 20 months, stayed in estrus for 3 days, and cycled at sleek intervals may or may not accurately represent bongos in the wild.
Gestation is 9 months, normally producing 1 offsprig.

PREDATORS

Primarily man, followed by spotted hyena and leopard.
Bongos brought to bay by dogs grunt and stamp defiance, and mothers defend calves against hynas.

DIFFERENCES IN BONQO BEHAVIOR

Expect to see and hear. Usual context and meaning.

Advertising Dominance

Snapping branches with the horns, often in connection with vegetation. Horning, by bulls and not followed by feeding on the broken branch.

Aggression

OTHER ACTIONS ASSOCIATED WITH THREAT DISPLAYS

Tree and bush horning and snapping branches.

Grunting and snorting.

FEMALE AGGRESSION

Medial-horn threat. Offensive threat.

Headlow posture. Defensive threat.

Submission

Kneeling and lying, Avoidance of persistent suitor.

Courtship

Male standing behind female stiffly erect. Mounting prelude.

Male bleats, clicks tongue, and licks lips.

Mother and Offspring

Social licking between mother and calf and between calves.

Play

Calves practice neck-fighting, head-shaking/throwing, nose-in-the-air, as well as chasing, etc.

Response to Predators

Style-trotting.

Laying tail over rump.

Snorting, distress-bleating, mooing.

Reprinted from "The Safari Companion" by Richard Estes
wildlife