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Thomson's Gazelle
Eudorcas thomsoniiThe small gazelle with the black side stripe.
The Thomson's gazelle - fondly the "tommie" - is one of East Africa's most abundant and recognizable small antelopes. Smaller and more richly marked than its look-alike Grant's gazelle, it carries a bold black stripe along each flank and can hit up to about 70 km/h. It is a grazer at heart and depends on water, so it stays on the short-grass plains where wildebeest and zebra crop the tall grass for it.
Thomson's Gazelle Quick Facts
What Is the Thomson's Gazelle?
The Thomson's gazelle (Eudorcas thomsonii) is a small gazelle of the open plains, in the same tribe (Antilopini) as Grant's gazelle, the gerenuk and the springbok. It was described by the zoologist Albert Gunther in 1884 and named after the Scottish explorer Joseph Thomson, who crossed Maasai territory in the 1880s. On safari it is almost always called a "tommie".
Its range is East African, not just Tanzanian. Thomson's gazelles occur mainly in Kenya and Tanzania, with smaller populations in South Sudan and a pocket of southwestern Ethiopia. Tanzania's northern short-grass plains - above all the Serengeti - hold some of the largest herds on Earth, but the species' heartland spans the whole Serengeti-Maasai Mara ecosystem across the Kenya border.
Why “Thomson's Gazelle”?
"Thomson's gazelle" honours Joseph Thomson, the Scottish explorer and geologist whose 1870s-80s journeys through what is now Kenya and Tanzania brought the species to scientific attention. The scientific name, Eudorcas thomsonii, places it in the genus Eudorcas (the "red gazelles"), alongside the red-fronted and Mongalla gazelles. Older works list it as Gazella thomsonii.
Signature Features
A Thomson's gazelle is small and slender, with a sandy-brown to rufous back fading to white underneath. Its most obvious mark is the bold black stripe running along each flank, set above a narrow rufous line. The rump patch is white and extends under the tail - unlike Grant's gazelle, whose white rump patch extends above the tail. That stripe-and-rump combination is the field mark every guide uses.
Both sexes carry horns: ringed, curving slightly back with the tips forward. Male horns reach 25-43 cm and are stout; female horns are 7-15 cm and more slender, and some females are hornless altogether. A short black-tufted tail and big dark eyes complete the look.
How Big Is a Thomson's Gazelle?
Thomson's gazelles stand about 55-82 cm at the shoulder and weigh roughly 15-35 kg, with males at the top of that range. They are the smallest of the common East African gazelles - noticeably more compact than Grant's gazelle - which is exactly why they lean on speed and alertness rather than size to survive.
Horns & Defence
Both sexes are horned (useful, though Grant's is also both-sexed). The horns are ringed and curve back then slightly forward. Males are unusually combative: Thomson's males settle rivalry by locking horns and pushing, unlike the more display-based Grant's males, whose fights are rarer and more ritualised. Females' horns are shorter and thinner, and some females lack them completely.
Habitat & Range
Thomson's gazelles are tied to open country: short-grass plains, open savanna and lightly bushed grassland. They avoid tall grass and dense thicket, because they need to see predators coming and because their food - short grass - grows in the open. They follow the rains to fresh growth and share range with wildebeest and zebra, whose trampling exposes the short grass Thomson's prefer.
A grazer that needs water
Unlike Grant's gazelle, Thomson's is a grazer and water-dependent. It drinks regularly and cannot subsist on food moisture the way Grant's can. This shapes where it lives: it stays on plains within reach of water and short grass, and it is the wildebeest-and-zebra association - not drought endurance - that lets it use the dry-season plains.
Thomson's Gazelle in Tanzania
Within Tanzania, Thomson's gazelles are a fixture of the northern circuit - especially the Serengeti short-grass plains, with strong numbers in Ngorongoro too. But the species' core spans the border: it is just as abundant in Kenya's Maasai Mara, and ranges into South Sudan and Ethiopia.
Serengeti, Tanzania
The single best place on Earth to see Thomson's gazelles - enormous resident and migratory herds on the open plains.
Serengeti safariNgorongoro, Tanzania
Present on the crater floor and highlands year-round, though this local population has been declining.
Ngorongoro safariKenya & the wider range
Maasai Mara, Amboseli and Tsavo in Kenya, plus South Sudan and a pocket of Ethiopia, complete the East African distribution.
With the Great Migration
Thomson's travel and graze alongside wildebeest and zebra, which crop the tall grass to the short growth they favour.
Behavior & Social Life
Thomson's gazelles are diurnal and form fluid herds of roughly 5-60 animals, with temporary gatherings into the hundreds during the migration. Herds split and merge freely and have no fixed hierarchy. They readily mix with other grazers - impala, Grant's gazelle, wildebeest and zebra - which helps everyone spot predators.
Breeding males defend small territories (marked with dung-and-urine middens and preorbital-gland scent) to attract females passing through; outside the rut, males form bachelor groups. When uneasy they snort, stamp and stot - a stiff-legged bouncing leap that both signals fitness to a predator and warns the herd. They do not "lead" one another; coordination comes from shared alarm signals, not from a dominant individual.
Diet & Feeding
Thomson's gazelles are mixed feeders that lean heavily to grazing. In the dry season short grass can be about 90% of the diet; they also take seeds and browse shrubs and forbs when grass is scarce. They deliberately graze behind larger herbivores - wildebeest and zebra trample and crop tall grass, leaving the tender short growth Thomson's prefer.
Because they are grazers, they are more water-dependent than Grant's gazelles and need to drink regularly - the main ecological divide between the two look-alikes.
Predators & Defense
Cheetahs are the specialist predator - built to run Thomson's down on open ground. Lions and leopards also take them (more by ambush), and spotted hyenas, African wild dogs and jackals prey on fawns; martial eagles may take very young calves. Defence is speed - up to about 70 km/h in bursts - plus intense vigilance, alarm snorts and tight bunching. Fawns are hidden separately in the grass rather than protected in a group.
Young & Lifespan
Breeding is year-round, with births peaking just after the rains. After a gestation of about 6 months a single fawn is born and hidden in the grass for its first weeks; the mother returns only a few times a day to nurse and clean it. The fawn samples solid food at about a month, is weaned by 5-8 months, and reaches maturity around a year (males show adult horns by two). Roughly half of all calves die in their first year. Lifespan is about 10-12 years in the wild.
Conservation Status
The IUCN lists Thomson's gazelle as Near Threatened, with an estimated total population of roughly 550,000 and a decreasing trend. Numbers fell by as much as 70% in parts of the Serengeti-Maasai Mara ecosystem between the 1970s and early 2000s, though the decline has since slowed to single digits per decade.
Main threats are conversion of plains to farmland, competition with livestock (and with the booming wildebeest population), poaching outside parks, and shifting rainfall. Protected areas - the Serengeti and Maasai Mara above all - hold the stable populations, which is why conserving connected plains matters as much as the parks themselves.
Safari Experience
For a Tanzania safari, Thomson's gazelle is commonly encountered on suitable Serengeti short-grass plains, and is frequently seen in Ngorongoro - although wildlife sightings can never be guaranteed. A classic sight among the herds of the Great Migration, watch for the black side stripe and white rump, and for stotting animals that signal a predator is near. They are Near Threatened and sensitive to habitat loss, so enjoy them with a conservation-minded operator and keep a respectful distance.
Comparisons
Two plains gazelles are easy to confuse at speed. Both are East African, but their ecology differs sharply:
| Feature | Thomson's Gazelle | Grant's Gazelle | Springbok |
|---|---|---|---|
| Scientific name | Eudorcas thomsonii | Nanger granti | Antidorcas marsupialis |
| Size | Smallest (~15-35 kg) | Larger (~35-80 kg) | Small |
| Flank mark | Bold black side stripe | White "pants" | Dark flank band |
| Rump patch | White, under tail | White, above tail | White, above tail |
| Feeding | Grazer (needs water) | Browser-leaning (water-independent) | Grazer-browser |
| Range | East Africa | East Africa | Southern Africa |
Did You Know?
Named for an explorer
"Tommie" honours Joseph Thomson, the Scottish explorer who crossed Maasai territory in the 1880s - not a scientist or a place.
Black side stripe
The bold flank stripe helps herd members keep contact with each other during fast group movements.
Stotting
Its stiff-legged bouncing leap is an honest "I'm fit, don't bother chasing me" signal to predators, and a warning to the herd.
Needs water
Unlike Grant's gazelle, Thomson's is a grazer that must drink regularly - the key ecological split between the look-alikes.
Up to about 70 km/h
One of the fastest small antelopes in Africa, using sheer speed to escape cheetahs and lions on open plains.
Near Threatened
An estimated 550,000 or so remain, but the trend is downward under farmland conversion, livestock competition and poaching.
On the Serengeti the tommies are everywhere at once - black-striped commas scattered across the grass, grazing low behind the wildebeest. When one stots, the whole plain seems to read it: a predator is close, and everyone lifts their head. They are small, and the odds are not in their favour, yet they fill the plains by the hundred thousand. That is the trick of being fast, alert, and never alone.
Gallery
Frequently Asked Questions
Eudorcas thomsonii. It sits in the gazelle tribe (Antilopini); older texts may list it as Gazella thomsonii.
Across East Africa: mainly Kenya and Tanzania, with smaller populations in South Sudan and southwestern Ethiopia. Tanzania is a major stronghold - the Serengeti - but the range spans the Kenya border too.
Yes - abundantly on the Serengeti plains and commonly in Ngorongoro. They are a near-certain sighting on a northern-circuit safari.
They are mixed feeders that lean heavily to grazing: short grass can be ~90% of the diet in the dry season, with seeds and shrub browse when grass is scarce.
Thomson's is the smaller of the two, with a bold black side stripe and a grazer's water dependence; Grant's is larger with white "pants" and is water-independent. The full side-by-side is in the Comparisons table above.
Yes - both sexes carry ringed horns; males' are stouter and longer while females' are slender and sometimes absent. (Full detail in Horns & Defence.)
It can reach up to about 70 km/h in short bursts, among the fastest small antelopes in Africa.
A stiff-legged bouncing leap. It is thought to signal fitness to a predator ("you won't catch me") and to alert the herd that danger is near. Much of what we know about stotting comes from Serengeti Thomson's gazelles.
Cheetahs are the specialist predator; lions, leopards, spotted hyenas and African wild dogs also take them, and jackals and martial eagles prey on fawns.
They stand about 55-82 cm at the shoulder and weigh roughly 15-35 kg, with males at the top of the range.
Near Threatened on the IUCN Red List (an estimated ~550,000 animals), with a decreasing trend driven by farmland conversion, livestock competition, poaching and shifting rainfall.
References & Further Reading
- Animalia.bio - Thomson's Gazelle: height 55-82 cm, weight 15-35 kg, top speed 80 km/h; lifespan ~10-20 years; Near Threatened; range Kenya and Tanzania (plus S. Sudan, Ethiopia).
- African Wildlife Foundation - Thomson's Gazelle: light-brown coat with dark side stripe, white rump patch under tail; both sexes horned (females shorter/smoother or none); gestation ~6 months; fawn hidden, nursed few times daily; dry-season diet ~90% grass.
- Animal Diversity Web - Eudorcas thomsonii: fluid groups of 5-60, temporary hundreds; mixed with impala/Grant's/wildebeest/zebra; territorial males; stotting as alarm; Near Threatened; lifespan ~10.5 years.
- The Animal Map - Thomson's Gazelle: open short-grass savanna; grazes with wildebeest and zebra; up to 80 km/h; preyed on by cheetah, lion, leopard, hyena, wild dog; Near Threatened; ~500,000+.
- IFAW - Thomson's Gazelles: IUCN Near Threatened; declined up to 70% in parts of Serengeti-Mara then slowed; threats farmland, livestock and wildebeest competition, poaching, climate; both sexes horned.
- Wikipedia - Thomson's gazelle: Eudorcas thomsonii; named for Joseph Thomson; Serengeti region of Kenya and Tanzania; short grassland with dry foundation.
