Okapi, Okapia johnstoni
TAXONOMY & NOMENCLATURE
(Benirschke & Hagey 2006) (Colbert 1938) (Daag & Forster 1982)
Describer (Date):P.L. Sclater (1901) Proceedings of the Zoological
Society of London, 1901 vol. I p. 50
Artiodactyla* (nearly 200 species of even-toed, hoofed mammals)
Suborder: Ruminantia (cud-chewing cattle, goats, sheep, bison, giraffes and more)
Family: Giraffidae (only two species - giraffes and okapis)
Genus: Giraffa camelopardalis (giraffe)
Genus: Okapi (okapi)
Species: Okapia johnstoni
*New anatomical and DNA evidence on the relationship between Artiodactyla (even-toed ungulates) and Cetacea (whales and dolphins) recently led to a merging of the two orders into a new group, Cetartiodactyla (Montgelard, 1997; reviewed in Kulemzina, 2009). As of October 2012, experts had not agreed on whether to define Cetartiodactyla as an official taxonomic order that would replace Artiodactyla and Cetacea. Some continue to list camels in the order Artiodactyla (Franklin, 2011) or use the term Cetartiodactyla without defining it as an order (IUCN, 2008).
Taxonomy and Phylogeny.
- Common Names: okapi
- Local Names:
- Atti (from Wambuti pygmy tribe)
- Okapi derived from the pygmy word O'Api which, when
spoken by pygmies, sounds like okapi.
- Other Scientific Nomenclature:
- Okapia liebrecht originated when, in the late 1800s,
Forsyth Major concluded that a specimen of skin and
skulls were a different species.
- Okapia erikssoni was named in 1903 by Lord
Rothschild who found the skin of a female okapi to be
different. (note: both observations were false).
- Okapi were unknown to western world (occupy dense African rainforest habitats) until discovered by Sir Harry Johnston in 1901. Species name is in Johnson's honor.
- Closest living okapi relative is the giraffe.
- 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 (cattle) family. (Benirschke & Hagey 2006) (Spinage 1968)
- Colbert (1938) made a detailed skeletal analysis of okapi and concluded that while they differed in many respects from giraffes, that they showed many primitive features of fossils of early giraffe relatives.
- Giraffe family (giraffes and okapi) dates to about 15-12 million years ago (Miocene) (Dagg & Foster 1982).
- Some two million years ago (Pleistocene) a now-extict okapi species (Okapia sp.) lived in East Africa in present-day Tanzania. At the same time in the same place, now extinct relatives of the giraffes existed.
DISTRIBUTION & HABITAT
(Hart & Hart 1988) (IUCN Redlist 2008) (Bodmer & Gubista 1988)
- Endemic to forests of Democratic Republic of Congo, occurring between about 500 m and 1,500 m elevation on both sides of the Congo River.
- Okapi populations in the Ituri / Aruwimi and adjacent Nepoko basin forests, and the forests of the upper Lindi, Maiko and Tshopo Basins; also well known in the Rubi-Tele region in Bas Uele. (IUCN Redlist 2008)
- Limited to closed, high canopy forests, occurring in a wide range of primary and older secondary forest types.
- Okapi don't range into gallery forests or into forest islands on the savanna and they don't stay in the disturbed habitats surrounding human settlements.
- Will occupy seasonally flooded areas when the ground is still wet, but they do not occur in truly wet sites or extensive swamp forest.
- Tree fall gaps are selected foraging sites for okapi during the early stages of regeneration (Hart & Hart 1989).
- Link to IUCN map
Mammal Databank. Based on Bodmer & Rabb (1992) and
(Bodmer & Rabb 1992) (Colbert,1938) (Dagg & Foster 1982) (Grzimek 1990) (Lindsey et al 1999)
- Males: range 200-300 kg
- Females: 25-50 kg (55 - 110 lb)
Length: 2.5 m (8 ft) average for both sexes
- Males: 1.5 m average (5 ft)
- Females: 4.2 cm ( 1.7 in) taller
- Okapi are a medium sized, extremely shy, even-toed ruminants related to giraffes; adapted for dense forest living
- Smaller than giraffes, with shorter necks (but necks still longer than most ruminants)
- Okapi backs are nearly level, while giraffe backs slope markedly towards the rear.
- Have long skulls, large black eyes, large ears.
- Teeth show giraffe-like pattern with large gap between incisors and premolars.
- 32 teeth
- Enamel is rough or wrinkled, like giraffes'
- Canine teeth are lobed, as are those of giraffes; lobes most obvious in unworn teeth of calves.
- Large bony capsule enclosing the middle ear bones (auditory bullae), common to many forest-dwelling ruminants
- These ear bones enhance hearing (plains-dwelling giraffes have much smaller auditory bullae).
- Can hear and transmit low-frequency sounds below audible range for humans, according to studies in 1992 at the San Diego Zoo and White Oak Conservation Center, Florida. (Lindsey et al 1999)
- Large sinuses in palate
- Muzzle is narrow, nearly pointed, lips mobile and muscular; together with tongue these adaptations well suited to selective feeding on preferred plants.
- Long, prehensile tongue (proportionally longer than the giraffe's).
- Dark-bluish colored with pointed extremity, smooth base, and papillae
- Can be extended 25 cm beyond snout to groom whole body, even wiping the eyes, cleaning the ears and nostrils.
- Skin-covered horns are permanent (not shed annually).
- Poor eyesight
- Cervical vertebrae not as elongated as in the giraffe.
- Five sacral (lower back) vertebrae (3-4 in giraffe)
- Only three tarsal (ankle area) bones; giraffes have four tarsal bones.
- Unlike giraffe, okapi has glands between toes on all 4 feet.
- Okapis have unusual chromosome numbers; rather the normal 46 chromosomes, numbers may be 45 or even 44 (Lindsey et al 1999)
- In other animals such variations are abnormal or fatal; okapis with such numbers are otherwise normal.
- Hybrids of okapis with other species not known.
- Reddish-brown to black, velvety pelage on body and face.
- Black muzzle and nostrils.
- Long, thick eyelashes; calf has long hairs around eyes or "false eyelashes" that disappear in time.
- Tapered white or creamy white horizontal stripes on rear and
upper front legs
- Anklets and stockings of white on lower legs
(perhaps enabling other okapi to easily follow through dark forests as
they have poor eyesight).
- Cheeks, throat and rear-most belly are whitish to gray or tan.
- Newborns have similar color and pelage; mane is conspicuous and is largely lost by adulthood
- Hairs of white stripes are longer than hairs in dark stripes
- Males are larger than females
- Males have skin-covered horns
- Females have no horns but do have "bumps" or hair whorls on head where horns would be; occasionally have rudimentary horns.
BEHAVIOR & ECOLOGY
(Bodmer & Gubista 1988) (Dagg 1960) (Hart 1992) (Hart & Hart 1988) (Lindsey et al 1999)
- Previously thought to be nocturnal, okapi have demonstrated diurnal
behavior, moving during both daylight and night hours.
- Feeding peaks at mid-morn and late afternoon.
- 30%-50% day spent resting
- Some movement during first few hours of darkness (most nocturnal
movement on moon-lit nights).
- Breeding females have the most stable home ranges averaging 3-5.5 km.
- Adult males with undefined, wide-ranging home ranges move more often
and greater distances. (Averaging 8-12 km)
- Remain solitary much of the time.
- 10% of total time is spent with other animals.
- Social grooming common in captives.
- 2 adults, 1 juvenile, and 1 young may inhabit the same home range.
- Groups of more than 3 have never been recorded other than in captivity.
- Calves remain within mother's home range during first 2-6 months after
- Okapi generally avoid individuals in adjacent home ranges
- Males and females spend very little time together
- Captive males shown to mark objects (bushes, trees) with urine, while
crossing legs in a dance-like movement.
- Marking occurs most often during courtship.
- Females mark using common defecation sites.
- Mark territory by rubbing necks on trees
- Home ranges:
Female 3 km-5 km,
Male largest home range > 10 km
- greatest 24 hr movement is 2.5 km
- most stable
- shared mainly with other female(s) and young
Subadults: 2 km-3 km
- 24-hr movement up to 4 km
- more restricted movement
- tendency to shift
Locomotion (Lindsey et al 1999) (Dagg 1960)
- Generally tranquil and non-aggressive.
- Males competing for females engage in ritualized neck fighting, head butting, and charging. (Prothero 2002)
- Aggressive behaviors include kicking, head-throwing, and slaps using
the side or top of head as a blow to flank or rump.
- Kicking is often symbolic without contact.
- Dominant animals have an erect head and neck posture while subordinates
may have head and neck on the ground.
- Pacing gait at about 16 kilometers/hour (10 mph) - foreleg and hindleg move forward together, followed by legs on other side
- Gallop gait attains speeds of about 56.3 kilometers/hour (35 mph) with same left side/ right side pattern.
- Like the giraffe, must splay the legs to reach the ground when drinking
- Includes gambols and capers, the pooky (head low and forward, rapid tail wags) and lie and rise (lie on ground, may roll on side, then stand up)(Bodmer
& Rabb 1985)
- Both sexes and all age classes engage in play behavior.
- Infants play more frequently than adults.
Vocalization (Bodmer &
- Dominance displays for both okapi and giraffe involve nose pointing away from the body's midline, which increases the visual impact of neck length. (Simmons and Scheepers 1996)
- Vocal communication more common than in giraffes.
- Consists of three types of vocal signals- the chuff, moan, and bleat.
- Chuffs are contact calls for all ages and both sexes.
- Infants use bleat vocalization for response from mother.
- Bleats emitted only by young animals < 7 months in stressful situations.
- Soft moaning sound by males during courtship.
- Whistles and bellows in acute distress situations.
- Vocalizations have infrasonic frequency components.
Intraspecies Interaction (Spinage 1968) (Bodmer &
- Secretes from glands of feet, leaving scent on low-lying herbage.
- Territory marked by urine or dung.
- Prior to mating, males and females sample urine to test for hormones
(scientific term is flehmen).
- Leopards represent significant cause of death for adult okapi.
- Serval cat and golden cats prey on young okapi.
- African rainforest natives use okapi skins for decorative belts.
DIET & FEEDING
(Bodmer & Gubista 1988) (Bodmer &
Rabb 1992) (Crissey et al 2001) (Hart 1992) (Hart & Hart 1988)
- Highly selective feeder on leaves, fruits, seeds, ferns, fungi of some 100 plant species.
- Prefer to browse in small forest openings where fallen trees allow growth of light-dependent plants; prefer fast-growing tree seedlings, shrubs and vines
- Okapi plants are only a temporary resource, scattered widely across the forests; most plants are not acceptable forage
- Do not choose shade-tolerant shrubs and select only a small proportion of all the plants available.
- Like giraffes, okapis use long, prehensile tongue to pull leaves off branches; a slender muzzle and flexible lips also help with choosing the "right" plants.
- Also ingest clay for its minerals, burnt charcoal, and bat guano found in
- Digestive system similar to other browsing ruminants.
- As in giraffes, gall bladder not present.
- Daily food intake (dry matter) of captive okapi ranges from 4.3-5.0 kg
REPRODUCTION & DEVELOPMENT
(Bodmer & Rabb 1992)
- Female estrus cycles occur every 15 days throughout the year, but are
- Males show few sexual hormonal fluctuations.
- Males enter female home ranges to mate.
- Males marking with urine occurs most frequently during courtship.
- During courtship, couple stands head to tail in a reverse parallel
position, accompanied by circling and mutual sniffing of inguinal
areas. Males and females flehmen, and males then go through a series
of behaviors including head and neck stretches, head forward and
upward positions, erect postures, nose lifting, and leg kicking. The
receptive female responds by a head-low posture, often with the tail
- Gestation lasts around 440 days.
- Signs in females or impending birth are swelling of the udder, viscous
discharges from the vagina and swelling of the udder (swelling of the
udder may occur 2 months before the birth).
- Females usually stand during birthing labor, but may recline for
- Mother typically ingests the fetal membranes and placenta.
- High frequency of contact and grooming between mother and infant after
birth. However, mothers may respond aggressively to the newborn,
striking with the head or hooves and sometimes killing the infant.
- Litter Size: one (only one record of twinning)
- Weigh 14-30 kg at birth; weight doubles by end of first month.
- Okapi milk has 1/3 more protein than cow's milk and low fat content.
- Okapi infants do not imprint strongly on mother and may nurse from more than one female at times.
- Infants spend about 80% of time at the nest during the first 2 months
(this lack of activity may serve to ensure rapid growth).
- Infants start taking solid food by the 3rd week, and rumination can be
seen by the 6th week.
- Weaning takes place at 6 months, although young may continue to suckle
for > 1 year.
- Horn development doesn't begin until about one year.
- Adult size reached at about 3 years
- Captive sexual maturity reached after 1 year 7 months (female) and 2
years 2 months (male).
- Longevity of captives that survive past the 1st year is usually 15-20
years; exceptionally up to 33 years
PATHOLOGY AND DISEASES
(Bodmer & Rabb 1992)
- Causes of mortality in captives are parasitism, aging, bacterial
infections, fungal diseases, viral diseases, and accidental trauma.
- A nematode worm, Monodontella giraffae that affects the liver and bile ducts, is the parasite causing the most deaths.
- Aging results in arthritis, ingrown hooves, and worn teeth.
- Susceptible to many common bacterial infections (including pneumonia
- Pox infections have caused severe illness in captives (usually doesn't
result in death).
- Diarrhea common in captives causing malabsorption of electrolytes and
(Gijzen & Smet 1974) (ISIS Web Site)
- Captive Breeding
- Okapis breed readily in captivity, but rearing of calves has
- Until the 1950s, roughly 50% died during the 1st month.
- Antwerp Zoo was the 1st to exhibit the okapi to visitors (1919); first okapi to survive in captivity also at Antwerp Zoo in 1928; she lived 15 more years.
- A male okapi named Congo came to the Bronx Zoo in 1937 and lived for 15 years.
- Common in many large zoos; currently being bred to maintain numbers;
difficult to keep because of delicate health
- Captive okapi population in North American zoos has 25 founders; in Europe there are 23 founders.
- Baruiti was born at the San Diego Zoological Park in 1962.
- ISIS captive population
POPULATION AND CONSERVATION STATUS
(Gijzen & Smet 1974) (Hart and Mwinyihali 2001) (IUCN Redlist 2008)
Threats to Survival
- Okapi has become the flagship species for the conservation of the lturi ecosystem in the Congo Basin.
- In Uganda, Okapi formerly occurred in the Semliki Forest, but is not known to survive there (IUCN Redlist 2008).
- 1925 Virunga National Park established; Africa's first national park.
- A 2006 survey by local trackers and by World Wildlife Fund and its Congolese governmental partner ICCN (the Congo Institute for Nature Conservation), and the Gilman Conservation International found okapi signs in Virunga National Park in Eastern Congo after no sightings there since the 1950's.
- In 2008 camera trap images of okapi obtained for first time; cameras set up in Virunga by Zoological Society of London and the Congolese Institute for Nature Conservation (ICCN).
- 1933: Okapi protection begins officially in Congo/Zaire.
- 1952: A captive breeding centre for okapi was first established at Epulu in the Ituri Forest, Zaire (now Democratic Republic of Congo or DRC)
- 1970: Maiko National Park established in DRC; it is not a World Heritage Site, but may have the most biodiversity of all the Congo's parks.
- 1987: Okapi Conservation Project begun by Gilman International Conservation to help protect native habitat in Ituri Forest of DRC.
- 1992: The Okapi Wildlife Reserve established
- Occupies 13,700 square kilometers (5,290 square miles) in DRC
- Is a Pleistocene refuge of exceptional species richness with a greater variety of mammals than any park in Africa:
- 15% of species are endemic which is one of the highest rates in the world
- Until recently preserved only by its inaccessibility;
- It has the highest known density of okapis known anywhere at approximately 2.5 animals per square kilometer (2. 5 per square mile)
- 1996: Okapi Wildlife Reserve designated as a United Nation World Heritage Site
- Within the reserve, some 5,000 okapi are protected
- This reserve encompasses the cultural center for two tribes of forest pygmy people - the Mubuti and Efe; okapi are not a significant part of their traditional diet,
- Strengthening protection of this reserve and Maiko National Park is the single most important means to ensure long-term survival of Okapi (IUCN 2008)
- 1998: Okapi Wildlife Reserve placed on list of World Heritage in Danger because of devastation by civil war, invasion by miners and militants and destruction of wildlife by hunting for bushmeat and ivory.
- 2008: Report for World Heritage in Danger List: populations of the endemic okapi in Okapi Wildlife Reserve have decreased by 43 %, with a loss of an estimated 2,000 animals (http://cmsdata.iucn.org/downloads/drc___okapi___dec_32_com_7a.pdf
- 2009: Population estimates are quite imprecise but may be between 10,000 and 35,000 individuals.
- IUCN status: (2009) Near Threatened
(version 3.1); population trend stable
- Primary threats:
- Bushmeat trade
- Deforestation, logging
- Human population growth, settlement
- Armed conflict/war/civil unrest/displaced human populations
(Hart and Mwinyihali 2001)
Other Web Resources
- Okapi Conservation Project - managed by Institute in Congo for the Conservation of Nature (ICCN), oversees the Okapi Wildlife Reserve in the Democratic Republic of the Congo
- Okapi Faunal Reserve (Encyclopedia of Earth) - Ituri forest ecology, excellent bibliography
- Okapi Wildlife Reserve (UNESCO - World Heritage List) - description of the reserve, documentation of goals, decisions, concerns, achievements to protect okapi and their habitat
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