Eudorcas thomsonii

Geographic Range

Thomson's gazelles are found in eastern Africa, in Kenya, Tanzania, and southern Sudan.

• Biogeographic Regions
• ethiopian ethiopian
  • native native

Habitat

Thomson's gazelles live in dry, short grasslands and shrubby savannas. They are an arid-adapted species and are able to stay in dry grasslands for longer than other plains ungulates in the same region, which migrate towards more moist habitats. They follow a similar sort of seasonal migratory pattern as other ungulates in their range, but they stay for longer on the wet season range and don't migrate as far north in the dry season.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland

• Other Habitat Features
• agricultural agricultural

Physical Description

Thomson's gazelles are small gazelles, the typical weight range is 15 to 35 kg. Males are larger overall, ranging in weight from 20 to 35 kg, females are from 15 to 25 kg. They have white bellies and reddish-brown backs, divided by a bold, black stripe laterally. Their rumps are white and their tails are black. Thomson's gazelles have reddish-brown fur on their faces, with a broad white stripe that extends from the eye to the nose and is bordered below by a black stripe. Males and some females have horns that curve backwards and are curved forwards distally in males. Females have smaller horns, if any, both lengthwise and in circumference. The horns are arrayed with a series of marked annulations. Thomson's gazelles resemble Grant's gazelles ( Gazella granti ) somewhat, although Grant's gazelles are larger overall, have horns that curve outwards, and the white of their rump extends to above the tail. Thomson's gazelles have a head and body length of 80 to 120 cm, a tail length of 15 to 27 cm, and height at the shoulder of 55 to 82 cm. They have prominent pre-orbital glands.

Thomson's gazelles are exceptionally fast runners, able to run at speeds up to 70 km/hour. They can outrun cheetahs if they can evade them for long enough because cheetahs can maintain high speeds for shorter times.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• ornamentation ornamentation

Reproduction

Thomson's gazelle males defend small territories and attempt to mate with females in that area. Females prefer rich foraging grounds, so preferred territories are those in areas with good grazing. Males use markings from preorbital glands and dung to advertise their territories and actively defend them against other males. They sometimes attempt to "herd" females in order to keep them in their territory for longer.

• Mating System
• polygynous polygynous

There is little available information on breeding in Thomson's gazelles. Thomson's gazelles mate twice yearly. Gestation is for 6 months and the majority of births occur right after the rainy season, with a single calf being born at 2 to 3 kg.

• Key Reproductive Features
• iteroparous iteroparous
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

Thomson's gazelle calves are precocial at birth, able to stand and walk soon after, although they spend their first days hidden and motionless in the grass. The mother will leave the young in high grass and frequently come back a few times during the day to nurse. After this hiding period, the young follow and accompany their mother with the herd.

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

Thomson's gazelles typically have a lifespan of 10.5 years in the wild. Approximately half of calves will die within their first year.

Behavior

Thomson's gazelles are social animals that are nomadic or migratory and specialized for cursorial locomotion. Thomson's gazelles usually form groups with a fluid association of 5 to 60 individuals, although temporary associations can number in the hundreds. Groups split and join readily and do not seem to have any permanent or exclusive membership or social hierarchy. They are also found in mixed-species herds with impalas ( Aepyceros melampus ) and Grant’s gazelles ( Nanger granti ). Males defend small territories during breeding seasons that they hope will attract females for mating opportunities. Outside of the breeding season, males form small bachelor herds or associate with females in loose groups.

• Key Behaviors
• cursorial
• diurnal diurnal
• motile motile
• nomadic nomadic
• migratory migratory
• social social

Home Range

Home range size of Eudorcas thomsonii is not reported.

Communication and Perception

Thomson’s gazelles are fairly silent animals that communicate more visually. When alarmed they will communicate to conspecifics by stotting, which is a stereotyped series of high jumps with the head held high and the legs stiff. Males communicate to other males and females by marking territories with their scent glands, including preorbital glands that they use to mark grasses and stems. Males also drop dung at spots in their territory to advertise ownership.

• Communication Channels
• visual visual
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Thomson’s gazelles graze mainly on short grasses. They eat twigs, seeds, and leaves from trees as well, especially during the dry season. Their smaller body size and drought tolerance make it possible for them to persist on arid grasslands that cannot support larger ungulates. Preferred grasses include Themeda , Cynodon , and Harpachne species. Foliage and seeds taken are from Acacia , Balanites , Boscia , Sida , and Solanum species.

• Primary Diet
• herbivore herbivore
  • folivore folivore

• Plant Foods
• leaves
• wood, bark, or stems
• seeds, grains, and nuts

Predation

Predators of Thomson's gazelles include lions, spotted hyenas, wild dogs, cheetahs, leopards, and jackals. During the calving season, the young are easy prey for all of these predators, as well as yellow baboons and pythons. Thomson's gazelles travel in small herds, which helps to protect individuals from predation. They are alert and can run quickly.

Ecosystem Roles

Thomson's gazelles are eaten by large predators such as lions, hyenas, and jackals. They modify plant communities through their grazing.

Economic Importance for Humans: Positive

Thomson's gazelles may be hunted for skin and meat. They are also part of the charismatic African ungulate fauna that supports a huge ecotourism industry in eastern Africa.

• Positive Impacts
• food food
• body parts are source of valuable material
• ecotourism ecotourism

Economic Importance for Humans: Negative

Thomson's gazelles may be killed by farmers who think that they compete with domestic livestock. However, their impact is likely to be negligible.

Conservation Status

According to the IUCN Red List, Thomson's gazelles are listed as near threatened. Although populations are stable in some areas and widespread, some populations have experienced severe declines since the 1970's. If E. thomsonii and E. mongalla (southern Sudan populations) are considered separate species, then E. thomsonii has a small and restricted distribution, which further threatens this species. In Kenya, the largest populations are found in the lands of the Masai Mara, the Masai Mara National Reserve, and the Laikipia and Kajiado rangelands. They occupy about half of their former range in Tanzania. In some areas population declines can be partially attributed to human impacts such as roads, habitat changes, and the impacts of tourism. Large parts of their range are already in protected areas, including the Serengeti National Park and Masai Mara National Reserve.

Other Comments

Thomson's gazelles were previously recognized as Gazella thomsonii and were also lumped with all red gazelles under Gazella rufifrons . Eudorcas rufina , previously also placed within Gazella rufifrons was known only from Algeria and is presumed extinct. Eudorcas rufifrons , also previously known as Gazella rufifrons , was more widespread, occurring throughout the savannas of central Africa, from Senegal and Mauritania in the west to the western side of the Nile in Sudan and portions of Sudan, Ethiopia, and Eritrea east of the Nile. Populations throughout that range are now highly fragmented and have declined dramatically because of hunting, competition with livestock, and habitat degradation. Some authorities recognize Eudorcas albonotata as a separate species (Sudan populations), here it is recognized as conspecific with Eudorcas thomsonii .

Additional Links

Encyclopedia of Life

Contributors

Amy Auman (author), Penn State University Park, Rachael Fye (author), Penn State University Park, Jacqualine Grant (editor, instructor), Penn State University Park, Tanya Dewey (author, editor), Animal Diversity Web.

References

African Wildlife Foundation, 1997. Wild Lives Guidebook: Profiles of East African Mammals . Washington, DC: African Wildlife Foundation.

Dorst, J. 1969. A Field Guide to The Larger Mammals of Africa . Great Britain: Houghton Mifflin Company Boston.

Estes, R. 1967. The Comparative Behavior of Grant's and Thomson's Gazelles. Journal of Mammalogy , Volume 48, Number 2: 189-209.

Feldhamer, G., L. Drickamer, S. Vessey, J. Merritt, C. Krajewski. 2007. Mammalogy: Adaptation, Diversity, Ecology 3rd edition . Baltimore: The John Hopkins University Press.

Kingdon, J. 1997. The Kingdon Field Guide to African Mammals . San Diego, CA: Academic Press.

2009. "ARKive: Images of Life on Earth" (On-line). Accessed February 23, 2009 at http://www.arkive.org/ .

2008. "IUCN 20008 Red List of Threatened Species:Eudorcas thomsonii" (On-line). Accessed April 24, 2009 at http://www.iucnredlist.org/details/8982 .