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Tragelaphus buxtonimountain nyala

By Maria Aleman

Geographic Range

Tragelaphus buxtoni is found in the highland mountains of Ethiopia. At one time, these animals ranged all over the southeastern mountains of Ethiopia. Currently, the range of T. buxtoni is limited to the Bale massif.

(Kingdon, 1997; Haltenorth et. al., 1977)

Habitat

Mountain nyalas live in woodland, bush, heath, and moorland areas at high altitudes, ranging from 3000 to 4200 meters. During the dry season, T. buxtoni spends time in woodlands, heath, and bush. During the rainy seasons, time is spent at lower elevations in grassland areas.

(Kingdon, 1997)

  • Range elevation
    3000 to 4200 m
    9842.52 to 13779.53 ft

Physical Description

T. buxtoni is a large bovid, weighing between 200-225 kg. The head and body length of these animals is 190 to 260 cm.

T. buxtoni has a grey-brown coat with two to five white strips down the flanks, and six to ten body spots. The coats of males darken with age, and have longer hair on the shoulders, neck, and back of thighs than do the coats of females. The coats of females are short and glossy all over. During the cold season, the coat can become shaggy. Calves are yellowish-brown without body strips. Horns, borne only by males, have 1.5 to 2 spirals, and the record length of horns is 188 cm. Ears are large and the tail is bushy and reaches down to the heels.

(Haltenorth, 1977; Kingdon, 1997; Nowak, 1999)

  • Range mass
    150 to 300 kg
    330.40 to 660.79 lb
  • Range length
    190 to 260 cm
    74.80 to 102.36 in

Reproduction

The mating system of this species has not been characterized in the literature, however, based upon characteristics of the species, it is most likely a polygybous breeder. The population is reportedly female baised, with females accounting for over 60% of the non-calf individuals observed. This indicates some level of polygyny. Other correlates of polygyny in this species include sexual dimorphism, with the males being much larger than the females, observed fighting between males, and the larger home range of males than of females. All of these characteristics are common in polygynous species.

(Huffman, 2003).

Mountain nyalas breed annually, with a peak of breeding occurring in December. Because calves of various sixzes are often present in a herd, it is likely that the actually birthing season is quite long. A female typically gives birth to one calf after a gestation of between 8 and 9 months. Weaning generally occurs around the sixth month. Sexual maturity is reached between 18 and 24 months.

(Kingdon, 1997; Huffman, 2003)

  • Breeding season
    There is a peak in breeding during December.
  • Range number of offspring
    1 (low)
  • Average number of offspring
    1
  • Range gestation period
    8 to 9 months
  • Average weaning age
    6 months
  • Range age at sexual or reproductive maturity (female)
    18 to 24 months
  • Range age at sexual or reproductive maturity (male)
    18 to 24 months

For the first few weeks of life, calves are often hidden. After that time, calves stay very close to their mothers. Calves remain with their mothers for up to two years at which time female young have already reached sexual maturity and may be pregnant.

Parental care is the responsibility of females only.

(Massicot, 2001)

Lifespan/Longevity

T. buxtoni is estimated to live in the wild for 15 to 20 years.

(Huffman, 2001)

  • Range lifespan
    Status: wild
    15 to 20 years

Behavior

Groups of mountain nyalas are led by females accompanied by their offspring and tend to consist of up to 13 individuals. Males are solitary, especially older males. Young males band together at times in groups of 2 or 3. Males often have horn wrestling matches or circling displays. Males have a range of up to 20 square kilometers. Females have a range of 5 square kilometers. Borth males and females show some dominance heirarchies.

Mountain nyalas are active during the day, and feed mostly during the morning and evening.

(Kingdon, 1997)

Communication and Perception

Food Habits

T. buxtoni generally feeds in the evenings and mornings. Mountain nyalas are browsers, and consume many species of grasses, herbs, and woody plants. They are known to eat shrubs, herbs, St. John's wort, lady's mantle, goosegrass, and plants in the tomato family.

(Massicot, 2001)

  • Plant Foods
  • leaves

Predation

The main predator on T. buxtoni is the leopard. However, poaching is another problem they face.

Newborn mountian nyalas use crypsis to evade predation. They lie alonein deep cover until they are large enough to travel with their mother's social unit. (Huffman, 2003)

Leopards, the principle predators of T. buxtoni are active at night, so it is likely that anything else these animals do to evade this predator occurs after dark. The species may have particular sleeping practices, such as sleeping in groups or in protected locations, that help reduce their vulnerability to predation.

Ecosystem Roles

As generalized browsers, mountain nyalas affect many plant populations. They make nutrients from plants available to large carnivores, providing a critical link in food webs.

Economic Importance for Humans: Positive

Humans have been known to poach these animals. There is therefore some benefit to humans imparted by these animals, in the form of food and trophies.

  • Positive Impacts
  • food

Economic Importance for Humans: Negative

There are no adverse effects of this species on humans.

Conservation Status

Humans have limited the habitat of T. buxtoni. There are currently only some 3000 total in the world, most of them confined to the Bale National Park.

(Nowak, 1999)

Other Comments

This species was not discovered until 1909 by Ivor Buxton. It was described by Lydekker in 1910. Its name is misleading in that mountian nyalas are more closely related to kudus than to nyalas.

(Huffman, 2001)

Contributors

Maria Aleman (author), Humboldt State University, Brian Arbogast (editor), Humboldt State University.

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

crepuscular

active at dawn and dusk

dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

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.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

food

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

herbivore

An animal that eats mainly plants or parts of plants.

internal fertilization

fertilization takes place within the female's body

iteroparous

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).

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.

polygynous

having more than one female as a mate at one time

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

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.

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Haltenorth, Theodor, D. 1977. A Field Guide to the Mammals of Africa including Madagascar. London: William Collins & Co..

Huffman, B. 2003. "MOUNTAIN NYALA" (On-line). Accessed April 30, 2003 at http://www.ultimateungulate.com/Artiodactyla/Tragelaphus_buxtoni.html.

Kingdon, Jonathan, 1997. The Kingdon Field Guide to African Mammals. London: Academic Press.

Massicot, Paul, August 18, 2001. "Animal Info - Mountain Nyala" (On-line). Accessed Novermber 13, 2001 at http://www.animalinfo.org/species/artiperi/tragbuxt.htm.

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

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