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. (Falchetti and Mostacci, 1993; Mochi and Carter, 1971; Walther and Grzimek, 1990)
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. (Mochi and Carter, 1971; Walther and Grzimek, 1990)
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. (Estes, et al., 1971; Falchetti and Mostacci, 1993; Walther and Grzimek, 1990)
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. (Estes, et al., 1971; Falchetti and Mostacci, 1993; Nowak, 1999; Walther and Grzimek, 1990)
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. (Falchetti and Mostacci, 1993; Walther and Grzimek, 1990)
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 (Falchetti and Mostacci, 1993; Falchetti and Mostacci, 1995; Walther and Grzimek, 1990)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.
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. (Estes, et al., 1971; Falchetti and Mostacci, 1993; Macdonald, et al., 1984; Walther and Grzimek, 1990)
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. (Estes, et al., 1971; Falchetti and Mostacci, 1993; Macdonald, et al., 1984; Walther and Grzimek, 1990)
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. (Estes, et al., 1971; Falchetti and Mostacci, 1993; Macdonald, et al., 1984; Walther and Grzimek, 1990)
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. (Walther and Grzimek, 1990)
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. (Falchetti and Mostacci, 1993; Walther and Grzimek, 1990)
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.
Nile lechwes are herbivorous, eating grasses, herbs, and waterplants. (Walther and Grzimek, 1990)
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. (Macdonald, et al., 1984; Walther and Grzimek, 1990)
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. (Keay and Eyre, 1971)
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. (Mochi and Carter, 1971)
There is apparently no negative impact of this species on humans.
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. (Falchetti and Mostacci, 1993; Falchetti and Mostacci, 1995; Walther and Grzimek, 1990)
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. (Falchetti and Mostacci, 1993; Falchetti and Mostacci, 1995; Walther and Grzimek, 1990)
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. (Falchetti and Mostacci, 1993; Falchetti and Mostacci, 1995)
Nancy Shefferly (editor), Animal Diversity Web.
Julia Corrie (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor, instructor), University of Wisconsin-Stevens Point.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
uses sound to communicate
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.
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.
uses smells or other chemicals to communicate
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
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.
union of egg and spermatozoan
an animal that mainly eats leaves.
A substance that provides both nutrients and energy to a living thing.
An animal that eats mainly plants or parts of plants.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
marshes are wetland areas often dominated by grasses and reeds.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
having more than one female as a mate at one time
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.
associates with others of its species; forms social groups.
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
uses touch to communicate
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
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 (International Zoo Yearbook, 34/0074-9664: 225-231.) at Rome Zoo.
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.