|Scientific Name:||Eudorcas thomsonii|
|Species Authority:||(Günther, 1884)|
Gazella thomsonii Günther, 1884
|Taxonomic Notes:||Included in the genus Eudorcas following Groves (2000) and Grubb (2005). The Mongalla Gazelle (E. albonotata) from the southern Sudan is sometimes regarded as a subspecies of Thomson's Gazelle, but is here treated as a species distinct from Thomson's (see Groves in press; FitzGibbon and Wilmshurst in press) (though see Grubb 2005 who includes it with Red-fronted Gazelle G. rufifrons).|
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Assessor/s:||IUCN SSC Antelope Specialist Group|
|Reviewer/s:||Mallon, D.P. (Antelope Red List Authority) & Hoffmann, M. (Global Mammal Assessment)|
Surveys have reported steep declines (60-70%) over periods of c. 20 years dating from the late 1970s in several places, including the main strongholds for the species: Serengeti, Masai Mara and Ngorongoro. Though overall numbers still seem to be falling, no declines on this scale have been reported recently. However, it is estimated that the decline over the last 3 generations (18 years) has reached 25%, and is very possibly higher, bringing the species very close to qualifying for Vulnerable under criterion A. Careful monitoring of population trends is needed and it is entirely feasible that new survey information could merit transfer of this species to a higher category of threat. This assessment considers E. thomsonii and E. mongalla as separate species when formerly they were assessed together. Under this arrangement, Thomson's Gazelle now has a relatively restricted distribution within East Africa, which should also be taken into consideration.
|Range Description:||Thomson?s Gazelle occurs widely within its historical range in the grasslands of southern and central Kenya. The largest populations occur in the Mara ranches, Masai Mara National Reserve and the Laikipia and Kajiado rangelands. In Tanzania, the species occupies about half of its former range in Acacia savannas and grasslands in the north (East 1999).|
Native:Kenya; Tanzania, United Republic of
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||East (1999) estimated the population size of Thomson's Gazelle at around 550,000 animals. The migratory population of the Serengeti ecosystem, which is Africa?s largest and most spectacular gazelle population, has been estimated at 174,015 (± 37,406 S.E.), based on data from the 2003 wet season (Mduma 2003), which is indicative of a steep decline since the estimate of 500,000 in the early 1980s (Sinclair and Norton-Griffths 1982). This would be consistent with a loss of large wild herbivores in the Masai Mara ecosystem in Kenya, where there are estimated to be ca. 40,000 in the Masai Mara reserve, a decline from ca. 100,000 in 1977 (Ottichilo et al. 2000). Likewise, Estes et al. (2006) report a decline of 60% from 1978-2005 in the Ngorongoro Crater. There are also reports of declines in the Ewaso Nyira basin, where numbers were estimated at ca. 33,000 in 1977, but at one-third of this in 1997 (Muchoki 2000).|
|Habitat and Ecology:||Thomson's Gazelle live in the short grasslands of Kenya and Tanzania (East 1999). They are primarily grazers, although they may include more forbs and fruits in their diect in the dry season; Thomson's Gazelle are relatively drought resistant, enabling them to remain out on the dry plains, long after most other ungulates have moved off to find wetter habitats (FitzGibbon and Wilmshurst in press). Thomson's Gazelle in the Serengeti follow a broadly similar pattern of seasonal movements to the Serengeti?s migratory wildebeest and zebra populations, but remain for longer in the wet season range on the open plains in the south-east of the ecosystem and do not migrate as far north as the Masai Mara reserve in Kenya during the dry season (East 1999).|
|Major Threat(s):||Although there do not appear to be any major threats to Thomson's Gazelle, there is evidence that several populations have undergone declines (FitzGibbon and Wilmshurst in press). In Ngorongoro Crater, these declines have been attributed to availability of water, tourist impacts, habitat modification due to exotic plant invasion, fire management, and road development (Estes et al. 2006).|
|Conservation Actions:||Thomson's Gazelle occur in a number of protected areas in their range, with core areas of the Serengeti-Mara population protected by the Serengeti N.P. and Masai Mara N.R., where wildlife tourism is the only permitted land use (FitzGibbon and Wilmshurst in press).|
East, R. 1999. African Antelope Database 1999. IUCN, Gland, Switzerland and Cambridge, UK.
Estes, R. D., Atwood, J. L. and Estes, A. B. 2006. Downward trends in Ngorongoro Crater ungulate populations 1986-2005: Conservation concerns and the need for ecological research. Biological Conservation 131: 106-120.
FitzGibbon, C. D. and Wilmshurst, J. F. In press. Eudorcas thomsonii. In: J. S. Kingdon and M. Hoffmann (eds), The Mammals of Africa, Academic Press, Amsterdam, The Netherlands.
Groves, C. P. 2000. Phylogenetic relationships within Antilopini (Bovidae). In: Vrba, E.S. and Schaller, G.B. (eds), Antelopes, Deer, and Relatives: Fossil Record, Behavioral Ecology, Systematics and Conservation, pp. 223?233. Yale University Press, New Haven, Connecticut, USA and London, UK.
Grubb, P. 2005. Artiodactyla. In: D. E. Wilson and D. M. Reeder (eds), Mammal Species of the World. A Taxonomic and Geographic Reference (3rd ed), pp. 637-722. Johns Hopkins University Press, Baltimore, USA.
Mduma, S. 2003. Aerial census in the Serengeti Ecosystem: wet season 2003 preliminary report. Tanzania Wildlife Research Institute, Conservation Information and Monitoring Unit, Arusha, Tanzania.
Muchoki, C. H. K. 2000. Livestock and wildlife populations trends (1977?97) in Ewaso Nyiro Basin, Kenya. African Journal of Ecology 38: 178-181.
Ottichilo, W. K., de Leeuw, J., Skidmore, A. K., Prins, H. H. T. and Said, M. Y. 2000. Population trends of large non-migratory herbivores and livestock in the Masai Mara ecosystem, Kenya, between 1977 and 1997. African Journal of Ecology 38: 202-216.
Sinclair, A. R. E. and Norton-Griffiths, M. 1982. Does competition of facilitation regulate migrant ungulate populations in the Serengeti? A test of the hypotheses. Oecologia 53: 364-369.
|Citation:||IUCN SSC Antelope Specialist Group 2008. Eudorcas thomsonii. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 23 April 2014.|
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