Capra walieWalia ibex

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Geographic Range

Capra walie, or the Walia Ibex, is found exclusively in the mountains of northern Ethiopia. Nearly all of the remaining population resides along 25 kilometers of the northern escarpment in the Simien Mountains National Park (Massicot, 2001).

Habitat

The Simien Mountains are characterized by huge gorges and gulleys, both of which carve out steep and jagged cliffs. Walia Ibex individuals inhabit only the high cliffs that rise above the lower elevated plateau, providing a potential risk of falling for careless individuals (Beyene, 2001)

At a high elevation and low-latitude, the cliff habitat is conducive to extremes in the seasonality of precipitation and daily temperature fluctuation.

The wet season runs from May until October and is correlated with abundant plant growth and diversity. During the dry season, foods in the form of grasses and shrubs dramatically disappear from most of the landscape (Dunbar, 1978).

At an average elevation of nearly 3500 meters, the Walia Ibex encounters tremendous temperature fluctuations from night to day. On a normal day, the temperature ranges from near freezing to more than 25 degrees Celsius. Despite the fluctuations in daily temperatures, seasonal differences in temperature are minimal due to Ethiopia's proximity to the equator (Nievergelt, 1990).

  • Range elevation
    2500 to 4500 m
    8202.10 to 14763.78 ft

Physical Description

Like other members of the genus Capra, Walia Ibex are sexually dimorphic in many aspects of appearance. In overall size, adult females weigh about 80 kilograms, roughly 50-60% of their male counterparts, which can weigh up to 125 kilograms (McDonald, 1984). Horns are semi-circular in shape and are found in both sexes, but male horns are more massive, reaching 110 centimeters in length (Beyene, 2001). Key features of horns are random knots and age rings, both of which distinguish individuals in a population (Dunbar and Dunbar, 1981).

Both sexes of Walia Ibex have black and white markings on their legs and a gray-white underside. The dorsal area is colored chestnut-brown and is darker in males (Nievergelt, 1990). In the wild, females are lighter in color and very inconspicuous (Dunbar, 1978). At older ages, males develop both a black chest and a "beard," further distinguishing the sexes (Dunbar and Dunbar, 1981).

Perhaps as an adaptation to its mountainous environment, Walia Ibex hooves have sharp edges and concave undersides that improves their grip by allowing them to work as a "suction cup" (Beyene, 2001).

  • Range mass
    80 to 125 kg
    176.21 to 275.33 lb

Reproduction

The typical mating system in C. Walie is polygyny, with dominant males siring a disproportionate amount of offspring during the breeding season. These males, because of their large size and fighting experience, are able to monopolize females by obtaining exclusive access to overlapping female home ranges (Dunbar and Dunbar, 1981).

C. walie is distinguished from other ibex species in its ability to breed at all times of the year. This may be possible because of the lack of temperature seasonality in the tropical Simien Mountains, producing no environmental costs to individuals that breed year-round (Nievergelt, 1990). Nevertheless, most often the Walia Ibex mates during the rut season, from February until April (Nievergelt, 1990). Peak sexual activity between males and females is observed between the months of March and June, overlapping with the short rut season (Dunbar and Dunbar, 1981). C. walie individuals reach sexual maturity at the age of one (Massicot, 2001). Both sexes continue to grow, however, and age is correlated with body size (Dunbar and Dunbar, 1981).

  • Breeding season
    February-June
  • Range number of offspring
    1 (low)
  • Average number of offspring
    1
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

Behavior

Walia Ibex are strictly crepuscular, only actively moving or feeding in early mornings and late evenings. During the middle of the day, individuals become very lethargic and tend to hide under the shade of dense brush away from the intense noon sun and any nearby predators (Dunbar, 1978).

Atypical of most mountain sheep, Walia Ibex females are more solitary than males outside of the breeding season. Instead, males form small groups with other males of similar age or size (Dunbar and Dunbar, 1981). This pattern of association is reversed during the rut season, with females forming nursery groups and males isolating themselves from one another in competition (Dunbar, 1978).

Fighting during the rut season occurs most frequently between males of similar age and size. This resulst from the fact that older males almost always win their fights with younger competitors. In fact, if the age difference between two males is significant, fighting will usually not take place at all (Dunbar and Dunbar, 1981).

Communication and Perception

Food Habits

A "generalized herbivore," Walia Ibex is both a grazer and a browser (Massicot, 2001). In fact, it utilizes a wide variety of grass and shrub material in its diet. Although grazing accounts for a significant part of its diet, this species spends most of its time feeding browsing in the cover of dense shrubs (Dunbar, 1978).

Foods eaten include: grasses, herbs, shrubs, bushes, creepers and lichens.

  • Plant Foods
  • leaves
  • lichens

Predation

Hyenas appear to be the only predators capable of killing an adult Walia Ibex. However, juveniles are at risk from a large variety of predators ranging from wildcats to foxes (Dunbar, 1978).

Economic Importance for Humans: Positive

  • Positive Impacts
  • food

Conservation Status

Over the last half-century, Walia Ibex has been considered one of the most endangered ungulates in the world (Nievergelt, 1990). Today, this species is deemed "critically endangered" primarily because of the very small population left in the wild. In fact, recent estimates predict the number of remaining individuals to be no greater than 400 (Massicot, 2001).

Pressures on the remaining population take the form of limited habitat and poaching. Although not as large a problem as was in the past, poaching still does occur to some degree inside the national park (Beyene, 2001). On another note, increasing the population numbers in the future will inevitably be difficult as estimates predict that Walia Ibex's current habitat can only handle around 2000 individuals (Beyene, 2001).

Other Comments

Today, C. Walie is the southernmost species of Ibex found in the world (Massicot, 2001).

Contributors

Rodgers Eckhart (author), University of Michigan-Ann Arbor, Ondrej Podlaha (editor), 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

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.

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.

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

seasonal breeding

breeding is confined to a particular season

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.

References

Beyene, B. 2001. "Walia Ibex" (On-line). Accessed November 13, 2001 at http://www.ethiopiafirst.com/Tour/endemic/Endemic-Walia-Ibex.html.

Dunbar, E., R. Dunbar. 1981. Competition and Niche Separation in a high-altitude herbivore community in Ethiopia. African Journal of Ecology, 19: 251-263.

Dunbar, R. 1978. Grouping Behavior of male Walia Ibex with Special Reference to Rut. East African Wildlife Journal, 16: 183-199.

Massicot, P. 2001. "Animal Info-Walia Ibex" (On-line). Accessed November 13, 2001 at http://www.animalinfo.org/species/artiperi/caprwali.htm.

McDonald, D. 1984. Goat Antelopes. Pp. 584-589 in D McDonald, ed. Encyclopedia of Mammals. New York: Facts on File Publications.

Nievergelt, B. 1990. Walia Ibex. Pp. 523-525 in B Grzimek, ed. Grzimek's Encyclopedia of Mammals. New York: Mcgraw-Hill Publishing Company.