ARTIODACTYLA

Full screen Artiodactyla Id code: amd146

Giraffidae
Okapia johnstoni

(P. L. Sclater, 1901)

(Eng) Okapi

(Fre) Okapi

Taxonomic notes

Generally considered a monotypic species (Bodmer & Rabb, 1992).

IUCN threat category

Lower Risk, near threatened (LR: nt).

Available information

Good information is available on the ecology of the species. Habitat, diet, and habits are described in Hart & Hart (1988, 1990), while Bodmer & Gubista (1990) focus on behavioural aspects of its ecology. Population genetic, status, reproductive biology, and captive breeding have been thoroughly investigated by De Bois (1988) and Foose (1978). Status and distribution are discussed in Verschuren (1975, 1978); more updated data on the matter are found in East (1995). The species' ecology is accurately described in Bodmer & Rabb (1992). De Bois & Van Elsacker (1988) review the existing literature up to then. General information on the ecology of the species is found in Estes (1991), Kingdon (1997), Pellew (1984) and Stuart & Stuart (1997).

Known extent of occurrence

This species is endemic to north and east former Zaire and adjacent areas probably extending as far east as western Uganda (East, 1996; Bodmer & Rabb, 1992; Wilson & Reeder, 1993). Its distribution map was first obtained from Bodmer & Rabb (1992) and then revised by Dr. R. East (23 June '97). The preliminary map was updated on the basis of more recent information found in Kingdon (1997) (Fig. 8.4.2.a).

Categorical-discrete (CD) distribution model

This species is restricted to tropical lowland forest. Secondary forest and clearings provide the most suitable feeding areas (Verschuren, 1978; Hart & Hart, 1988).

Based on these environmental preferences, the following scores were assigned (Fig. 8.4.2.b) (Tab. 8.4.2.a):

Score
1	Secondary and degraded forests.
2	Forest mosaics, primary and swamp forests.
3	Savanna and cropland.

	suitable		moderately suitable		unsuitable		Total
OCCURRENCE	km²	%	km²	%	km²	%	km²	%
certain	117 420	11	168 966	16	16 403	2	302 789	28
possible	278 697	26	381 191	35	120 909	11	780 797	72
Total	396 117	37	550 157	51	137 312	13	1 083 586	100

Tab 8.4.2.a: Cumulative size (km²) of areas pertaining to each environmental suitability class within the Extent of Occurrence.

	Number Patches (NP)	Mean Patch Size (MPS) km²	Patch Size SD (PSSD) km²	Largest Patch Index (LPI) %	Mean Shape Index (MSI)	Area-Weighted Mean Shape Index (AWMSI)
suitable	769	514	6 808	16.95	1.31	13.44
moderately suitable	673	817	14 468	38.82	1.32	19.47
Total AO	107	8 832	89 887	98.87	1.37	14.19

Tab 8.4.2.b: Area of Occupancy fragmentation indexes.

Probabilistic-continuous (PC) distribution model

The output of the probabilistic-continuous (PC) distribution model is shown in Fig. 8.4.2.c.

Validation

No occurrence of the species within the four sample areas.

Comments and conservation issues

The whole EO of this species, including areas of both "certain" and "possible presence", appears to be largely suitable although most of the range is classified as moderately suitable. According to the CD model, and to a lesser extent the PC model, the southern area of possible presence is interspersed with extensive patches of unsuitable areas. The overall fragmentation is high as shown by the small MPS and LPI of both suitable and moderately suitable areas. The same indexes for the total AO are higher and fragmentation seems to be much reduced, although the AWMSI indicates a high interspersion of different suitability classes. In the areas of certain presence, only 3% of the total AO is protected, while the percentage for the areas of possible presence is about 12%.

OCCURRENCE	SUITABILITY CLASS	inside	outside	Total
certain	suitable	0.28	10.56	10.84
	moderately suitable	0.37	15.23	15.59
	unsuitable	0.12	1.40	1.51
possible	suitable	2.35	23.37	25.72
	moderately suitable	4.21	30.97	35.18
	unsuitable	1.03	10.12	11.16
Total		8.35	91.65	100

Tab 8.4.2.c: Percent of environmental suitability classes within EO (as obtained from the categorical-discrete distribution model) inside and outside the protected areas.

References

Bodmer R.E., Gubista K.R. (1990). Une note sur la structure sociale de l'okapi en liberte. Nature et Faune: 6, 49-51.

Bodmer R.E., Rabb G. (1992). Okapia johnstoni. Mammalian Species: 422, 1-8.

De Bois H. (1988). The studbook population of the Okapia johnstoni: some remarks on the current demographic and population genetic status. Acta Zoologica et Pathologica Antverpiensia: 80, 53-64.

De Bois H., van Elsacker L. (1988). Bibliography of the okapi, Okapia johnstoni. another 20 years later . Acta Zoologica et Pathologica Antverpiensia: 80, 65-85.

East R. (Ed.) (1995). Antelope survey update. IUCN/SSC Antelope Specialist Group: n° 1.

East R. (Ed.) (1996). Antelope survey update. IUCN/SSC Antelope Specialist Group: n° 2.

Estes R.D. (1991). The Behaviour Guide to African Mammals. Including Hoofed Mammals, Carnivores, Primates. The University of California Press.

Foose T.J. (1978). Demographic and genetic models and management for the okapi (Okapia johnstoni) in captivity. Acta Zoologica et Pathologica Antverpiensia: 73, 119-195.

Hart J.A., Hart T.B. (1988). A summary report on the behaviour, ecology and conservation of the okapi (Okapia johnstoni) in Zaire. Acta Zoologica et Pathologica Antverpiensia: 80, 19-28.

Hart J.A., Hart T.B. (1990). Rapport de synthese sur le comportement, l'ecologie et la conservation de l'okapi (Okapia johnstoni) au Zaire. Nature et Faune: 6, 48-52.

Kingdon J. (1997). The Kingdon field guide to African Mammals. Academic Press, London and New York: Natural World.

Pellew R.A. (1984). Giraffe and okapi. In: Macdonald D.W. (Ed.). The Encyclopedia of Mammals. Facts on File, New York: pp 534-541.

Stuart C., Stuart T. (1997). Field guide to the larger mammals of Africa. Struik Publishers.

Verschuren J. (1975). Wildlife in Zaire. Oryx: 13 (2), 149-163.

Verschuren J. (1978). Note sur la distribution geographique et la situation actuelle de l'okapi. Okapia johnstoni. Acta Zoologica et Pathologica Antverpiensia: 71, 15-30.

Wilson D.E., Reeder D.M. (Eds) (1993). Mammal Species of the World: A Taxonomic and Geographic Reference. Second edition. Smithsonian Institution Press, Washington D.C.