Artiodactyla Id code: amd178Bovidae Litocranius walleri (Brooke, 1879) (Eng) Gerenuk (Fre) Gazelle de Waller, gazelle-giraffe Taxonomic notes No significant taxonomic notes. IUCN threat category Lower Risk, conservation dependent (LR: cd). Available information The species has been widely studied in Tsavo National Park (Kenya); little information is available for the rest of its range of distribution. The main aspects of the species' ecology are described in Leuthold (1978, 1984). Seasonal feeding habits and activity patterns are discussed in Leuthold (1970) and Leuthold & Leuthold (1978). Some data on the population density are found in Leuthold & Leuthold (1976), while aspects of its behaviour are analysed in Gosling (1981) and Reif & Klingel (1991). General information on the species' ecology is found in Estes (1991), Kingdon (1997) and Stuart & Stuart (1997). The species' presence in Somalia, Ethiopia, and Eritrea is discussed in Funaioli (1971) and Yalden et al. (1996); both authors also give some notes on its ecology. East (1988) analyses its status and distribution, and describes its habitat requirements. Known extent of occurrence  Endemic to eastern Africa, the gerenuk is restricted to east Ethiopia, Somalia, Kenya and north-eastern Tanzania (Wilson & Reeder, 1993). First obtained from Leuthold (1978), its distribution map was then updated using the more accurate country maps in East (1988) as indicated by Dr. R. East (23 June '97) (Fig. 8.6.21.a). Categorical-discrete (CD) distribution model The species occurs in open bushland and arid thornland (Funaioli, 1971; Kingdon, 1997; East, 1988). Based on these environmental preferences, the following scores were assigned (Fig. 8.6.21.b) (Tab. 8.6.21.a):
Tab 8.6.21.a: Cumulative size (km2) of areas pertaining to each environmental suitability class within the Extent of Occurrence.
Tab 8.6.21.b: Area of Occupancy fragmentation indexes. Probabilistic-continuous (PC) distribution model The output of the probabilistic-continuous (PC) distribution model is shown in Fig. 8.6.21.c. Validation No occurrence of the species within the four sample areas. Comments and conservation issues The known EO is nicely matched by the output of both models: only the areas in northern Tanzania are classified as lower quality. All together more than 80% of the EO is classified as potential AO, and it does not appear to be substantially fragmented in many patches. The AWMSI indicates that the boundary lines of the suitable patches are strongly discontinuous and the largest patches have irregular shapes. Like most gazelles, this species is not very abundant outside the protected areas, as hunting and poaching is intensive. A significant percentage of the AO (about 13%) is included in the existing protected areas. Although the species is classified as Lower Risk, the amount of protected AO may not be sufficient to ensure the long-term conservation of the species.
Tab 8.6.21.c: Percent of environmental suitability classes within EO (as obtained from the categorical-discrete distribution model) inside and outside the protected areas. References East R. (Ed.) (1988). Antelope Global Survey and Regional Action plans, Part I: East and North East Africa. IUCN/SSC Antelope Specialist Group. Estes R.D. (1991). The Behavior Guide to African Mammals. Including Hoofed Mammals, Carnivores, Primates. The University of California Press. Funaioli U. (1971). Guida breve dei mammiferi della Somalia. Istituto Agronomico per l'Oltremare. Biblioteca Agraria Tropicale. Gosling L.M. (1981). Demarcation in a gerenuk territory: an economic approach. Z. Tierpsychol.: 56, 305-322. Kingdon J. (1997). The Kingdon field guide to African Mammals. Academic Press, London and New York: Natural World. Leuthold W. (1970). Preliminary observations on food habits of gerenuk in Tsavo National Park, Kenya. E. Afr. Wildl. J.: 8, 73-84. Leuthold W. (1978). On the ecology of gerenuk Litocranius walleri. J. Anim. Ecol.: 47, 561-580. Leuthold W. (1984). The graceful gerenuk. In: Macdonald D.W. (Ed.). The Encyclopedia of Mammals. Facts on File, New York: pp 582-583. Leuthold W., Leuthold B.M. (1976). Density and biomass of ungulates in Tsavo East National Park, Kenya. E. Afr. Wildl. J.: 14, 49-58. Leuthold B.M., Leuthold W. (1978). Daytime activity patterns of gerenuk and giraffe in Tsavo National Park, Kenya. E. Afr. Wildl. J.: 16, 231-243. Reif U., Klingel H. (1991). Hiding behaviour in wild Gerenuk (Lithocranius walleri) fawns. Z. Saugetierkunde: 56, 159-168. Stuart C., Stuart T. (1997). Field guide to the larger mammals of Africa. Struik Publishers. 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. Yalden D.W., Largen M.J., Kock D., Hillman J.C. (1996). Catalogue of the mammals of Ethiopia and Eritrea. 7. Revised checklist, zoogeography and conservation. Tropical Zoology: 9, 73-164.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||