Okapia johnstoniokapi

Geographic Range

Okapis are found only in the tropical forests of northeastern Zaire. They prefer altitudes between 500 and 1,000 m, although they may venture above 1,000 m in the eastern montane rainforests. One sighting occurred at 1,450 m on Mt. Hoyo, in the upper Ituri. The range of the okapi is limited by high montane forests to the east, swamp forests below 500 m to the west, savannas of the Sahel/Soudan to the north, and open woodlands to the south. Okapis are most common in the Wamba and Epulu areas (Bodmer 1992).

Habitat

Okapis occur in the dense rainforests at middle elevations within their range. They frequent river banks and stream beds and may occasionally venture into areas of secondary forest growth (Bodmer 1992).

Physical Description

The okapi has a form superficially resembling that of a horse. Average body length is 2.5 m, and average height at the shoulder is 1.5 m. The neck is relatively long in comparison to that of other ruminants, and the ears are large and flexible. The body is chocolate-brown, with creamy white horizontal stripes on the legs and hindquarters and white stockings on the ankles. The cheeks, throat, and chest are whitish-gray or tan (Bodmer 1992). The unique color pattern of the okapi allows it to disappear into the background of dense vegetation and rotting leaves where it lives (Grzimek 1990). Male okapis have hair-covered horns not exceeding 15 cm in length. The horns are fused to the frontal bones over the orbits and project rearward. Females may be slightly red in color, lack horns, and average 4.2 cm taller than males. Both males and females have interdigital glands on the front and hind feet (Bodmer 1992). The most giraffe-like feature of the okapi is the long black tongue which is used for plucking buds, leaves, and branches from trees and shrubs as well as for grooming (Kingdon 1979). In addition, the walking gait of the okapi closely resembles that of a giraffe. Both giraffe and okapi simultaneously step with the front and hind leg on the same side of the body rather than moving alternate legs on either side like other ungulates (Dagg, 1960).

  • Range mass
    200 to 300 kg
    440.53 to 660.79 lb

Reproduction

In the wild, okapis are solitary, coming together primarily for mating. Okapi courtship and mating rituals are known only from observations done in zoos. Partners begin courtship by circling, sniffing, and licking eachother. Eventually, the male asserts his dominance by extending his neck, tossing his head, and thrusting one leg foreward. This display is followed by mounting and copulation. After mating, the male and female part (Grzimek 1990). The gestatation period lasts about 440 days (Bodmer 1992), and females retreat into dense forest vegetation to give birth (Grzimek 1990). Newborn okapis weigh 14-30 kg at birth. They are precocial and may nurse after 21 minutes and stand after just 30 minutes. Young spend the first day or two of life following the mother around and exploring the environment. After this, they find a suitable hiding spot and make a nest. For the next two months, they spend 80% of their time in this nest. Hiding behavior appears to promote rapid growth and provides protection from predators. A disturbed calf lies motionless in its nest, and a female okapi will rush to aggressively defend her calf from danger. During the hiding stage, young nurse relatively infrequently and do not defecate. These strategies help keep them undetected by predators. Weaning occcurrs at about 6 months, although young may continue to suckle for more than a year. Young males begin developing horns at one year of age, and both males and females reach adult size at about three years. In captivity, the youngest female to breed was 1 year 7 months old, and the youngest male was 2 years 2 months old. The okapi's lifespan is about 30 years in captivity, but data from wild populations is unavailable (Bodmer 1992).

  • Average number of offspring
    1
    AnAge
  • Average gestation period
    458 days
    AnAge
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    578 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    790 days
    AnAge

Lifespan/Longevity

Behavior

Okapis occur alone or in mother-offspring pairs. They have overlapping home ranges of several square kilometers and typically occur at densities of about 0.6 animals per square kilometer. The home ranges of males are generally slightly larger that those of females. Although they are not social animals, okapis tolerate eachother in the wild and may even feed in small groups for short periods of time. Knowledge of okapi social behavior comes primarily from observations of captive animals. Males appear to mark with urine, and both males and females mark by rubbing their necks on trees. Okapis seem to exhibit several aggressive behaviors including kicking and headthrowing. In captivity, dominant animals hold their necks straight and heads higher than subordinates, and the placing of the neck and head on the ground is a clear sign of submission. In addition, social grooming and play behavior seem to be common for both juveniles and adults. Vocal communication is important in many captive social interactions including mother-offspring bonding and distress calls, as well as courtship behavior (Bodmer 1992).

Communication and Perception

Food Habits

Okapis are diurnal and forage along fixed, well-trodden paths through the forest (Grzimek 1990). They feed primarily on the leaves, buds, and shoots of more than 100 different species of forest vegetation (Bodmer 1992). Many of the plant species fed upon by the okapi are known to be poisonous to humans. Additionally, okapis eat grasses, fruits, ferns, and fungi. Examination of okapi feces has revealed that the charcoal from trees burnt by lightning is consumed as well. Field observations indicate that the okapi's mineral and salt requirements are filled primarily by a sulfurous, slightly salty, reddish clay found near rivers and streams (Grzimek 1990).

Economic Importance for Humans: Positive

Immediately following their discovery in 1900, zoos around the world attempted to obtain okapis from the wild. These initial attempts were accompanied by a high mortality rate due to the rigors of traveling thousands of miles by boat and by train. In more recent years, shipment by airplane has proven more successful. Today, many zoos keep and breed okapis, and many people visit these zoos each year to see them (Grzimek 1990).

Conservation Status

The okapi was not recognized by western scientists until 1900, when Harry Johnston sent two pecies of "zebra-like" skin to London (Kingdon 1979). More recently, the okapi has been extirpated from Uganda and, since 1933, protected by law in Zaire. Despite its patchy distribution, the okapi is common in much of its current range and is therefore not listed as a threatened species by international agreement. However, habitat loss due to deforestation as well as poaching continue to restrict the range of the species and take their toll on the population. Another great danger to the okapi is lack of knowledge about it outside of zoos. Little field research has been done on the species due to its inaccessible habitat and reclusive nature (Bodmer 1992).

Other Comments

The okapi has been the subject of considerable genetic interest ever since chromosome research revealed that individuals having 2n=45 were more common than those having the expected 2n=46. This anomaly has been related to the Robertsian fusion phenomenon (Bodmer 1992).

Contributors

Eric Palkovacs (author), University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

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

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.

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.

native range

the area in which the animal is naturally found, the region in which it is endemic.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

viviparous

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

References

Bodmer, R.E., and G.B. Rabb. 1992. Okapia johnstoni. Mamm. Species, 422:1-8

Dagg, A.I. 1960. Gaits of the Giraffe and Okapi. Journal of Mammalogy, 41(2):282

Grzimek, B. 1990. Grzimek's Encyclopedia of Mammals. Vol. 5. McGraw-Hill Publishing Company, New York.

Kingdon, J. 1979. East African Mammals an Atlas of Evolution in Africa. Vol. 3. Academic Press, London.