Okapi (Okapia johnstoni)

The okapi is a medium-sized giraffid with a form superficially resembling that of a horse (Equus caballus).

Average body length is 2.5 meters, and average height at the shoulder is 1.5 meters. Body masses of adult okapis average 250 kilograms and range from 200 to 300 kilograms.

The okapi has a striking visual appearance. The body is a generally dark chocolate-brown velvety pelage that contrasts with the tapered white or creamy white horizontal stripes on the rear haunches and upper front legs. The white coloring continues across the anklets and stockings on the lower legs. The cheeks, throat, and the distal ventrum are white, grey, or tan and provide additional contrast to the dark reddish brown to black colors of the back and sides. The hairs of the okapi’s white stripes are longer than the hairs in the dark stripes.

The unique color pattern of the okapi allows it to disappear into the background of dense vegetation and rotting leaves where it lives. Okapi also have poor eyesight and the coloring can help guide calves. Young okapi rely on the white coloring of the anklets and stockings on the lower legs of the okapi to contrast against the dark forest, thus allowing them to easily follow behind.

Okapi have large, black eyes with long, thick eyelashes. Okapi calves have long hairs around the eyes, referred to as false eyelashes that disappear in time.

The dolichocephalic skull of the okapi is like those of other paleotragines. The okapi’s skull shows primitive characteristics for the family, including a large parietal region, short diastema, and large auditory bullae. Large palatine sinuses are also distinctive of the okapi, among giraffids. A large bony capsule enclosing the middle ear bones, (the auditory bullae,) is common to many forest-dwelling ruminants and is related to an acute sense of hearing. In accord, there are large external ear lobes, 25 centimeters in length from the crown, that are readily flexed. Both features may be correlated with infrasonic sound reception. In fact, studies in 1992 at the San Diego Zoo and White Oak Conservation Center in Florida have demonstrated that the okapi can hear and transmit low-frequency sounds below audible range for humans.

The brachyodont cheek teeth and dolichocephalic skull of okapi are like those of other paleotragines. However, unlike its fossil relatives of the Palaeotraginae, Okapia johnstoni has slightly smaller permanent incisors, slightly larger permanent cheek teeth and the second upper deciduous molar lacks an external cingulum.

Okapi show a giraffe-like pattern in their teeth with a large gap between the incisors and the premolars. The dental formula is 0/3, 0/1, 3/3, 3/3, with a total of 32 teeth, consistent with all giraffids. The enamel is rough or wrinkled, like giraffes, and the deciduous and permanent canines are incisor-like and bilobate, lobed as are those of giraffes. The lobes are most obvious in the unworn teeth of calves. The incisors form a semicircle at the end of the lower jaw.

There is sexual dimorphism in the okapi. Physically, females may be slightly red in color and average 4.2 centimeters taller than males. They also lack the ossicones that males possess. Instead, females possess bumps, or hair whorls, where the horns of males are located. Sometimes, however, small rudimentary horns may be present in females. There are no other cranial features of the okapi that have been found to be significantly dimorphic.

Male okapi possess permanent ossicones, a pair of supraorbital, hair-covered frontal horns that are fused to the frontal bones over the orbits and project rearward. These horns are variable in girth and length, but do not exceed 15 centimeters above the skull. The hair on the tops of these horns is often rubbed to the bone, but they do not shed. Only male okapi possess these horns, whereas females possess hair whorls where the horns of males are located. Sometimes, however, small rudimentary horns may be present in females. There are no other cranial features of the okapi that have been found to be significantly dimorphic.

The relationships between the length of the forelimbs and hind limbs in okapi are similar to those found in other artiodactyl genera.

The okapi has larger, more flexible ears and a relatively longer neck than other ruminants, though, which is perhaps correlated with locomotor coordination of the giraffid pacing gait.

Unlike the giraffe, the okapi has interdigital glands on all four feet, with the glands being slightly larger on the front feet.

The most giraffe-like feature of the okapi is the long, dark blue-violet, prehensile tongue which is used for plucking buds, leaves, and branches from trees and shrubs, as well as for grooming. This tongue is proportionally longer than that of the giraffe (Giraffa camelopardalis) and has a pointed extremity, smooth base, and papillae on the surface. The okapi can extend its tongue 25 centimeters beyond its snout in order to groom the entirety of its body, even wiping the eyes and cleaning the ears and nostrils.

Because of their unusual chromosome numbers, okapis have been the subject of considerable genetic interest. Chromosome research has revealed that okapi individuals having 45 chromosomes, (2n=45,) were more common than those having the expected 46 chromosomes, (2n=46.) Okapi can even have 44 chromosomes, (2n=44.) In other animals, such variations are abnormal or fatal. Okapis with such numbers, however, are otherwise normal. This anomaly has been related to the Robertsian fusion phenomenon.

The okapi’s lifespan is about 15-33 years in captivity, but data from wild populations is unavailable.

Generation length is broadly estimated at around eight years, based on calculations made for the global captive population.

SEXUAL DIMORPHISM

Taller, Redder Females Lacking Ossicones

BODY HEIGHT

1.5-1.7 m. / 4.6-5.6 ft.

BODY LENGTH

2-2.5 m. / 6.6-8.2 ft.

BODY MASS

180-356 kg. / 397-785 lb.

DENTAL FORMULA

I ⁰⁄3, C ⁰⁄1, P ³⁄3, M ³⁄3, ×2 = 32

LIFESPAN

15-30 yr.

GENERATION LENGTH

8 yr.

LOCOMOTION

Unguligrade

Although the okapi is currently classified in the Giraffidae family and its closest living relative is the giraffe (giraffa camelopardalis), there is scientific debate on where the okapi should be classified. Some researchers dissent, pointing out that important differences in reproductive organs, fetuses, bile acid salts, and skeletal anatomy make the okapi more likely to not belong in the giraffe family at all, but to be a closer relative of the nilgai antelope in the bovid or cattle family.

The okapi is readily distinguishable from its nearest extant relative, the giraffe.

Firstly, the two species are allopatric and occur in separate, non-overlapping geographical areas. The okapi occurs in the rainforests of central Africa and the giraffe inhabits sub-Saharan savanna and woodlands.

Physically, the body of the okapi is smaller than the giraffe, with the neck and leg proportions of the okapi more resembling those of bovid and cervid ruminants than those of giraffe. The okapi’s back is nearly level while the giraffe’s back slopes markedly toward the rear. Cervical vertebrae of the okapi are unelongated, unlike those of the giraffe, and number five sacral in contrast to the three or four of the giraffe. Okapi also only have three tarsal ankle bones compared to the four tarsal bones of the giraffe. Lastly, the okapi also has interdigital glands on all four feet, with the glands being slightly larger on the front feet, unlike giraffes.

Only male okapi possess ossicones; however, small rudimentary horns may be present in females, whereas both male and female giraffes have horns.

The okapi’s coloring also contrasts with that of the giraffe as the okapi possess individually variable, tempered white and creamy white horizontal stripes extending anteriorly from the posterior face of the hindlimbs and rump.

Okapi have few vocalizations, but vocalize more than giraffes.

KINGDOM

Animalia

PHYLUM

Chordata

CLASS

Mammalia

ORDER

Cetartiodactyla

FAMILY

Giraffidae

GENUS

Okapia

SPECIES

johnstoni

SUBSPECIES

None

The okapi’s scientific name, Okapia johnstoni, is a combination of the Mbuti pygmy word, O’Api, and a tribute to the okapi’s western discoverer, Sir Harry Johnston.

The okapi was not recognized by western scientists until 1901. Until then, the okapi had eluded potential discovery. While exploring the Congo from 1882-1886, Wilhelm Junker deemed a striped piece of animal skin from a Makapi as the skin of a musk deer. In June 1889, Captain Jean Baptise Marchand saw a timid animal that was unidentifiable from zoological literature, which he assumed an antelope.

In 1900, Johnston traveled to the Ituri Forest after hearing rumors of an Abada unicorn and an unusual Atti donkey from explorers such as Sir Henry Morton Stanley, whom had spent many years exploring Africa and published In Darkest Africa. In Africa, Johnston was informed by the Mbuti pygmies that there was a large, donkey-like animal with stripes that inhabited the area, which they called an O’api. Months later at Fort Mbeni in the Semliki Forest, a post commanded by Lieutentant Meura, Johnston was given bandoliers and belts made by the Bambuba tripe from a striped animal which they called an “okapi.”

After organizing an expedition, Johnston began following O’api tracks, led by Mbuti guides. He was surprised by the tracks, expecting the single-hoofed impression of a zebra, donkey, or horse, but instead finding a cloven-hooved footprint possessing two toes on each foot. Later, Lieutenant Meura sent Johnston two pieces of striped skin that Johnston then sent to London. Thus, the okapi was given the species name, Johnstoni in Johnston’s honor.

ALTERNATE

Atti, Congolese Giraffe, Dwarf Giraffe, Forest Giraffe, Makapi, O-Api, Zebra Giraffe

GROUP

Corps, Herd, Journey, Totter, Tower

MALE

Bull

FEMALE

Cow

YOUNG

Calf

Okapis are endemic to tropical forests of northeastern Zaire and are generally limited to altitudes between 450 and 1,000 meters. However, they have been reported at altitudes above 1,000 meters in the eastern montane rainforests, with one sighting at 1,450 meters on Mount Hoyo in the upper Ituri. They do not occur lower than 500 meters or in the swamp forests of western Zaire.

In general, the geographical range is limited in the east by high montane forests, in the west by swamp forests, in the north by savanna of the Sahel/Soudan, and in the south by open woodland. The specific distribution ranges through the Ubangui, Uele, Aruwimi, and Ituri rainforests; from Libangi on the Ubangui River in the west to near Lakes Kivu and Edward in the east, north to Faradje, and south to the Sankuru and Maniema districts.

They are most common in the Wamba and Epulu areas.

Recently, the okapi has been extirpated from Uganda.

EXTANT

Congo

EXTINCT

Uganda

Okapi are limited to closed, high canopy forests and dense rainforests between 450 and 1,500 meters above sea level, the middle elevation for their range. They occur in a wide range of primary and older secondary forest types and frequent river banks and stream beds.

They will use seasonally inundated areas when the substrate is still wet, but they do not occur in truly inundated sites or extensive swamp forest. Tree fall gaps are selected as foraging sites for okapi during the early stages of regeneration.

Okapi do not extend into gallery forests or the forest-savannah ecotone and do not persist in disturbed habitats surrounding larger settlements.

FOREST

Subtropical/Tropical Moist Lowland, Subtropical/Tropical Swamp

Okapi were previously thought to be nocturnal, but are now considered a mainly diurnal species. Okapi feeding peaks at mid-morning and late afternoon when the okapi forages along fixed, well-trodden paths through the forest. They mostly forage during the day, but have also been recorded feeding at night.

30-50% of the okapi’s day is spent resting. There may be some okapi movement during the first few hours of darkness and most nocturnal movement occurs on moon-lit nights.

Knowledge of okapi social behavior comes primarily from observations of captive animals.

In the wild, okapi are mainly solitary and occur alone or in mother-offspring pairs. They primarily only come together for mating as males and females spend very little time together. Although they are not social animals, okapi can tolerate each other in the wild and may even feed in small groups for short periods of time. 10% of an okapi’s total time is spent with other animals.

Social grooming and play behavior is common in captive okapis. Both sexes and all age classes will engage in play behavior, though infants play more frequently than adults. Playing includes gambols and capers, the pooky, in which the okapi will hold its head low and forward while rapidly wagging its tail, and the lie and rise, in which the okapi will lie on the ground and roll about before standing up again.

Okapis are generally tranquil and non-aggressive, but males can be aggressive when competing for females. Male okapi will engage in ritualized neck fighting, head butting, and charging in order to compete for females. They also seem to exhibit several aggressive behaviors including kicking, head-throwing, and slaps using the side or top of the head as a blow to the flank or rump. Kicking is often symbolic, however, not often making contact.

Male okapi stretch their necks as a way of competing for dominance, a behavior most commonly seen during breeding. Dominant okapi have an erect stature with their necks held straight and their heads tilted high. They may also point their noses away from the body’s midline, which increases the visual impact of the neck’s length. Subordinates may place the neck and head on the ground, a clear sign of submission.

Marking of okapi territory occurs most often during courtship. Males appear to mark with objects, such as trees and bushes, with urine while crossing their legs in a dance-like movement. Females mark using common defecation sites. Both, males and females, mark territory by rubbing their necks on trees.

Vocal communication is important in okapi social interactions including mother-offspring bonding and distress calls, as well as courtship behavior. Okapis have few vocalizations, but have more than the giraffe (Giraffa camelopardalis). Their vocalizations consist of three types of vocal signals, the chuff, the moan, and the bleat. These vocalizations have infrasonic frequency components. Chuffs are contact calls for all ages and both sexes. Bleats are only emitted by young animals less than seven months old in stressful situations, as a distress call, in order to get a response from the mother. Okapi also use whistles and bellows when in acute distress situations. Lastly, soft moaning sounds are made by males during courtship.

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. Okapi also have a pacing gait and can gallop. The okapi has a pacing gait at about 16 kilometers per hour, or 10 miles per hour. When pacing, they move their forelegs and hindlegs forward together, followed by the legs on the other side. When galloping, the okapi can attain speeds of about 56.3 kilometers per hour (35 miles per hour). They use the same left side-right side pattern when galloping.

Like the giraffe, the okapi must splay its legs to reach the ground when drinking.

Even though they have large eyes, okapi have poor eyesight. Calves rely on the white coloring of the anklets and stockings on the lower legs of the okapi to contrast against the dark forest, thus allowing them to easily follow behind.

Okapi have defined, non-exclusive, overlapping home ranges of several square kilometers and typically occur at densities of about 0.6 animals per square kilometer. Two adults, one juvenile, and one young may inhabit the same home range, but groups of more than three have never been recorded outside of captivity. Calves remain within their mothers’ home ranges during the first 2-6 months after birth. Okapi generally avoid individuals in adjacent home ranges. Adult female okapis average home ranges of 3-5 kilometers squared (1.9-3.1 miles squared,) and travel up to 2.5 kilometers, or 1.6 miles, in a day. They mainly share their home ranges with other females or their young. Breeding females have the most stable home ranges. In comparison, adult males have slightly larger home ranges, averaging 13 kilometers squared, but usually no smaller than 10 kilometers squared, or 6.2 miles squared. Male okapis will travel up to 4 kilometers, or 2.5, miles per day. Adult males with undefined, wide-ranging home ranges move more often and move at greater distances averaging 8-12 kilometers per day. Lastly, subadult okapis maintain home ranges of 2-3 kilometers squared, or 1.2-1.9 miles squared. They have a more restricted movement than adults and have a tendency to shift.

CIRCADIAN RHYTHM

Diurnal

Okapi are unique in being the only species of forest ungulate to depend on understory foliage. They feed primarily on the leaves, buds, grasses, fruits, ferns, fungi, and shoots of more than 100 different species of forest vegetation.

Many of the plant species fed upon by the okapi are known to be poisonous to humans.

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.

PREFERENCE

Generalist

STYLE

Forager

Okapi courtship and mating rituals are only known from observations done in zoos.

Courtship of females okapi by males is unobtrusive and cautious. Okapi partners begin courtship by circling, sniffing, and licking each other. 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 ways.

The okapi gestation period lasts about 440 days, and females retreat into dense forest vegetation to give birth.

Okapi newborns weigh 14-30 kilograms at birth and have similar color and pelage as adults with a few marked differences. Okapi calves are born with a conspicuous mane that is largely lost by adulthood. They also have long hairs around their eyes, referred to as false eyelashes that will disappear in time.

After birth, an okapi calf will find a suitable hiding spot and make a nest for itself. For the next two months, the calf will spend 80% of its time alone in this nest. The mother will leave the infant alone for extended periods of time, however, when threatened, a disturbed calf will lie motionless in its nest while the mother okapi will aggressively rush to defend her calf from danger. Hiding behavior appears to promote rapid growth and provides protection from predators. During the hiding stage, young nurse relatively infrequently and do not defecate. These strategies help keep them undetected by predators.

Young okapi spend the first day or two of life following the mother around and exploring the environment. They are precocial and may nurse after 21 minutes and stand after just 30 minutes. Weaning occurs 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.

Female okapi reach sexual maturity at 1-2 years and males at 2 years. In captivity, the youngest female to breed was 1 year 7 months old, and the youngest male was 2 years 2 months old.

BREEDING SEASON

May-June, November-December

ESTROUS CYCLE

15 Days

PARENTAL INVESTMENT

Maternal

GESTATION

440 Days

LITTER

1

WEANING

6-12 Months

INDEPENDENCE

9-12 Months

SEXUAL MATURITY

1-2 Years

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.

WEARING APPAREL, ACCESSORIES

Local

FOOD

Local

Okapi have been undergoing a decline since at least 1995 that is ongoing and projected to continue, in the face of severe, intensifying threats and lack of effective conservation action which is hindered by the lack of security. The rate of decline is estimated to have exceeded 50% over three generations, (24 years,) based on figures from surveys in the Okapi Wildlife Reserve (Réserve de Faune à Okapis; RFO) suggesting a 43% decline over the period 1995-2007, which some reports suggest continued in the period thereafter.

The RFO remains the best protected site and it is inferred that the rate of decline here is at least equalled in other parts of the okapi’s range. Although monitoring is only available to support estimates of declines in RFO since 1995, reports of declines or extirpations in other parts of the range and loss and degradation of habitat have been ongoing since 1980.

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.

FRAGMENTATION

Not Fragmented

A 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.

Hunting for meat and skins is also a threat and okapi decline rapidly in areas where there is persistent use of snares. In some areas, okapi are targeted for bushmeat whereas in others they are taken only incidentally.

The most prominent current threat to okapi is the presence of illegal armed groups in and around key protected areas. These groups prevent effective conservation action, even surveys and monitoring in most sites, and engage in and facilitate elephant poaching, bushmeat hunting, illegal mining (gold, coltan and diamonds), illegal logging, charcoal production, and agricultural encroachment. In a notorious incident in June 2012, armed rebels attacked the RFO HQ and killed seven people and all 14 captive okapi.

RESIDENTIAL & COMMERCIAL DEVELOPMENT

Housing & Urban Areas

AGRICULTURE & AQUACULTURE

Annual & Perennial Non-Timber Crops

ENERGY PRODUCTION & MINING

Oil & Gas Drilling, Mining & Quarrying

BIOLOGICAL RESOURCE USE

Hunting & Trapping Terrestrial Animals, Logging & Wood Harvesting

HUMAN INTRUSIONS & DISTURBANCE

War, Civil Unrest, & Military Exercises

The okapi is not included in the CITES Appendices.

The okapi is a fully protected species under Congolese law and the species is a national symbol, appearing on the insignia of the Institut Congolais pour la Conservation de la Nature (ICCN) and on Congolese banknotes.

Since 1933, the okapi has been protected by law in Zaire.