Kobus megaceros

Geographic Range

Nile lechwes ( Kobus megaceros ) have a very restricted geographic range. They are found only in the Bahr-el-Ghazel district of the Southern Sudan, and in Machar Gambella marshes of Ethiopia in Africa.

• Biogeographic Regions
• ethiopian ethiopian
  • native native

Habitat

Nile lechwes are found in swamps, dry and flooded grass marshes, and steppes. The species is known to inhabit short grass, high reed, and cane thickets.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland

• Wetlands
• marsh marsh
• swamp swamp

Physical Description

Nile lechwes exhibit sexual dimorphism so extreme that males and females look as if they belong to different species. Males and females can easily be distinguished from one another based on pelage color, size, and ornamentation. However, both sexes have long, coarse hair; elongated, narrow hooves; a short nose; and a long tail (with a length between 40 and 50 cm).

Older males are blackish-brown, with a white spot behind the horns. This white spot connects to a white band on the neck, which broadens on the withers. Males have long, lyre-shaped horns that are 48 to 87 cm in length. Males are an average of 165 cm long, 100 to 105 cm tall at the shoulders, and weigh between 90 amd 120 kg.

Females are pale yellow, and lack horns. Young males look like females until they reach 2 or 3 years of age. At this time, the color of the pelage changes and the horns begin to grow. Females are an average of 135 cm long, 80 to 85 cm tall at the shoulders, and weigh between 60 and 90kg.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently
• ornamentation ornamentation

Reproduction

Kobus megaceros has a harem mating system where only the dominant male is sexually active. Mating starts with a unique form of marking. The male bends his head to the ground and urinates on his throat and cheek hair. He then rubs his dripping beard on the female's forehead and rump, and mating ensues.

• Mating System
• polygynous polygynous

Both sexes are sexually mature at 2 years of age. The gestation period averages 235.5 days, after which a single calf is born. newborns weigh about 4.5 to 5.5 kg.

Female can ovulate again approximately one month after giving birth, leading to a mean interbirth interval of 11.6 months. Most females have a calf every year. The sex ratio at birth is 1:1. Calving takes place in the wet season in the wild, however, in captivity this species mates throughout the year, and so can produce young throughout the year. However, even in captivity, there is a birth peak, and this occurs between February and May.

Calves exhibit hiding behaviors, and are independent from their mothers between 6 and 8 months of age, which is the time of weaning in other members of this genus.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• viviparous viviparous

Most artiodactyls are precocious at birth, and are able to keep up with their mother during foraging at a young age. It is likely that this species is similar.

Females care for their young, nursing them, and protecting them. Calves remain with their mothers until they are weaned at 6 to 8 months of age. Male parental care has not been reported for these animals.

• Parental Investment
• no parental involvement
• altricial altricial
• pre-fertilization
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • protecting
    • female

Lifespan/Longevity

Adults live an average of 10 to 11.5 years in captivity. The lifespan in the wild is similar. The species is reported to have a maximum longevity of 19 years in captivity. In spite of their potential lifespan, most K. megaceros do not live a very long time. The infant mortality rate is high in the wild because yearling Nile lechwes are infected with warble flies, which bring many down. The 30-day infant mortality rate (36%) is high in captivity because of inbreeding.

Behavior

Nile lechwes are diurnal and social. They are gregarious, but territorial, animals. They forms herds of 50 to 500 individuals. Within a herd, there form three social classes: nursing-females and their young, bachelor males, and mature males with territory.

Mating occurs in a lek. Males with a territory will sometimes allow one "satellite" male from the bachelor class into their territory. The satellite males are not allowed to copulate, though they may do so undetected occaisionally, and their role is to keep out other unwanted males. Satellite males have better food resources and a 12x greater chance of gaining territory than other bachelors. There is no cooperative defense by the herd when attacked, but females will defend their offspring from smaller predators by direct attack, mainly kicking, usually in response to the young's distress calls.

Nile lechwes are attracted to water and wetlands, so during the wet season the population is spread out over water resources. During the dry season, these animals gather around the few water resources left. They will rest in areas above the water level such as dry banks, sandbanks, and islands, and flee to water when disturbed. They are good swimmers, but prefer to wade in shallow water.

• Key Behaviors
• terricolous
• diurnal diurnal
• motile motile
• sedentary sedentary
• territorial territorial
• social social
• dominance hierarchies dominance hierarchies

Home Range

The size of the home range of these animals has not been reported.

Communication and Perception

Nile lechwes communicate much like other waterbucks and kobs. There is a mixture of visual signaling and tactile communication. When displaying, they will rear high in the air in front of their opponent and turn their head to the side. They achieve a submissive posture by stretching their neck and head forward horizontally. The submissive female may also make snapping movements while stretching her neck. When fighting, males will duck their heads and use their horns to push against each other. If one male is significantly smaller than the other, he may move next to the larger male in a parallel position and push from there, which prevents the larger male from pushing with all his force.

In addition, during the reproductive season, males urinate on themselves, then smear the urine onto the female before mounting her. It is difficult to see this as anything other than soem form of chemical, as well as tactile, communication.

Although vocalizations were not reported in the literature reviewed here, because they are mammals, it is likely that they do vocalize, and that these vocalizations play some role in communication.

• Communication Channels
• visual visual
• tactile tactile
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Nile lechwes are herbivorous, eating grasses, herbs, and waterplants.

• Primary Diet
• herbivore herbivore
  • folivore folivore

• Plant Foods
• leaves

Predation

Natural predators of Nile lechwes include lions, leopards, cape hunting dogs, and crocodiles. Humans are also major predators of these animals. Nile lechwes are particularly vulnerable to cooperative hunting because of their close association with aquatic habitats. In the 1950's, traditional lechwe drives (chilas) were common, each one killing about 3,000 individuals.

Ecosystem Roles

Nile lechwes may help reduce grass fires by trampling the grass when grazing, making a natural firewall. They are also an important source of food for crocodiles because of the amount of time these animals spend in the water.

Economic Importance for Humans: Positive

Nile lechwes are a highly prized trophy to an African hunter and may be traded for food or other resources. They were also traditionally hunted as a source of food.

• Positive Impacts
• food food
• body parts are source of valuable material

Economic Importance for Humans: Negative

There is apparently no negative impact of this species on humans.

Conservation Status

Nile lechwes are not on the IUCN red list or in CITES, but they are in need of conservation efforts. Populations are confined to two small areas where any change in conditions would be detrimental to their status. The regions they inhabit are also places of severe political and social unrest, which contributes to a dim outlook for their survival.

The main threats to K. megaceros are habitat loss and hunting pressures. Hunting in the Sudan requires a special license. In Ethiopia only six animals per year are allowed to be captured with a special license. In 1971, a law limited hunters to two animals per a lifetime, making the animal a rare commodity.

The most recent census found 30,000 to 40,000 in the wild and 150 in captivity. Their current IUCN status is "Satisfactory" in Sudan and "Rare" in Ethiopia.

Better conservation efforts are needed in zoos. Falchetti (1993) believes that the genetic make-up of most of the captive individuals is not adequate for a long-term survival program aiming at preserving 90% of the average heterozygosity of the original population for 200 years. Capturing wild individuals in Ethiopia is possible and would reduce the inbreeding and consequently the infant mortality rate in captive animals.

Additional Links

Encyclopedia of Life

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Julia Corrie (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor, instructor), University of Wisconsin-Stevens Point.

References

Corbet, G., J. Hill. 1991. Pp. 132 in A World List of Mammalian Species , 3rd Edition. New York, NY, USA: Oxford University Press.

Estes, R., V. Geist, F. Walther. 1971. Social Organization of the African Bovidae. Pp. 166-205 in The Behaviour of Ungulates and its Relation to Management . Morges, Switzerland: Unwin Brothers Unlimited.

Falchetti, E., B. Mostacci. 1995. A case study of inbreeding and juvenile mortality in the population of Nile lechwe ( Kobus megaceros ) at Rome Zoo. International Zoo Yearbook , 34/0074-9664: 225-231.

Falchetti, E., B. Mostacci. 1993. The Nile lechwe: PVA factors and guidelines to captive management. International Zoo Yearbook , 32/0074-9664: 60-69.

Keay, R., S. Eyre. 1971. An Example of Sudan Zone Vegetation in Nigeria. Pp. 70-80 in World Vegetation Types . London, England: The Macmillan Press Ltd.

Macdonald, D., D. Whyte, D. Macdonald. 1984. The Encyclopedia of Mammals . New York, NY, USA: Facts on File Publications.

Mochi, U., T. Carter. 1971. Hoofed Mammals of the World . New York, NY, USA: Charles Scribner's Sons.

Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition . Baltimore and London: The Johns Hopkins University Press.

Walther, F., B. Grzimek. 1990. Reedbucks, Waterbucks, and Impalas. Pp. 448-461 in Grzimek's Encyclopedia of Mammals , Vol. 5. New York, NY, USA: McGraw Hill Publishing Company.