About Eudorcas thomsonii (Günther, 1884)
The scientific name of Thomson's gazelle is Eudorcas thomsonii (Günther, 1884). Thomson's gazelle is a relatively small species of gazelle, standing 60–70 cm (24–28 in) at the shoulder. Males weigh 20–35 kg (44–77 lb), while slightly lighter females weigh 15–25 kg (33–55 lb). Key facial features include white rings around the eyes, black stripes running from the corner of each eye to the nose, rufous stripes running from the horns to the nose, a dark nose patch, and a light forehead. Its coat ranges from sandy brown to rufous, with a black band running across the flanks from the upper foreleg to just above the upper hind leg, and a buff band located above this black stripe. Short black streaks mark the gazelle's white rump, and its solid black tail measures 15–27 cm (5.9–10.6 in). Males have well-developed preorbital glands near the eyes, which they use for scent-marking territories. Both sexes have horns that curve slightly backward, with their tips facing forward. These horns are highly ringed: they measure 25–43 cm (9.8–16.9 in) in males and 7–15 cm (2.8–5.9 in) in females. Female horns are more fragile than those of males, and some female Thomson's gazelles are even hornless. Grant's gazelle is very similar in appearance to Thomson's gazelle, but can be told apart by its larger size and a white rump patch that extends over the top of the tail. The two recognized subspecies of Thomson's gazelle differ in appearance. The eastern Thomson's gazelle is the larger of the two, and has fainter facial markings. The Serengeti Thomson's gazelle has a whiter face with more conspicuous markings. In the eastern Thomson's gazelle, female horns are shorter relative to male horns to a greater degree, and the horns are more divergent. Thomson's gazelle lives in savannas and grassland habitats in East Africa, particularly in the Serengeti region of Kenya and Tanzania. It has narrow habitat preferences, favoring short grassland with a dry, sturdy foundation, though it will migrate into tall grassland and dense woodland. Thomson's gazelles are mixed feeders. In wet seasons, they eat mainly fresh grasses, but during dry seasons they consume more browse, especially foliage from woody plants, bushes, and herbaceous forbs. They are dependent on short grass, and their populations can become highly concentrated at the start of the rains when grass grows quickly. In the Serengeti, Thomson's gazelles follow larger herbivores such as plains zebras and blue wildebeests, which cut down taller grasses. In the wild, Thomson's gazelles have a lifespan of 10–15 years. Their major predator is the cheetah, which can reach higher running speeds, but Thomson's gazelles can outlast cheetahs in long chases and make turns more quickly. This small antelope can run extremely fast, reaching speeds up to 80 km/h (50 mph), and can run in a zigzag pattern—an adaptation that often helps it escape predators. Thomson's gazelles are also sometimes preyed on by leopards, lions, African wild dogs, hyenas, Nile crocodiles, and African rock pythons; their fawns are sometimes preyed on by eagles, jackals, and baboons. A distinctive behavior of Thomson's gazelles is a bounding leap called stotting or pronking, which they use to startle predators and display strength. During courtship and reproduction, a male gazelle follows a female and sniffs her urine to determine if she is in estrus, a process called the Flehmen response. If the female is in estrus, the male continues to court her and mount her. Females leave the herd to give birth to single fawns after a five- to six-month gestation period. Breeding occurs year-round, with a peak in births around January and February, and some populations have a second birth peak around June and July. Newborn fawns weigh 2 to 3 kg (4.4 to 6.6 lb). Females can give birth twice per year, producing one or two fawns per litter. When giving birth, a female gazelle crouches as the newborn fawn drops to the ground, tearing the umbilical cord. The mother then licks the fawn clean of amniotic fluid and birthing tissues. This licking may also stimulate the fawn's blood circulation, or act as a scent label that lets the mother recognize her fawn. For the first six hours of the fawn's life, it moves and rests with its mother, but eventually spends more time away from its mother and hides in the grass. The mother stays near the fawn and returns to nurse it daily. Mother and fawn may spend an hour together before the fawn goes back to lie down and wait for the next nursing. Mother gazelles may associate with other mother gazelles, but fawns do not form group nurseries called "kindergartens". Mothers defend their young against jackals and baboons, but do not defend them against larger predators. Sometimes a female can fend off a male baboon by headbutting him with her horns to protect her fawn. Before returning to nurse their hidden fawns, females display noticeable peaks in maternal vigilance. They stop almost all other activities to focus on watching for danger. They move slowly toward the fawn's hiding spot, stopping frequently to scan the surrounding area. Observations have recorded several females engaging in "sham" feeding behavior, where they lower their heads to the ground as if feeding before quickly raising them back up to scan. In one observed case, a female actively searched for predators by climbing to the top of a small hill to scan the area before approaching her fawn's hiding spot. As the fawn approaches two months of age, it spends more time with its mother and less time hiding, until it eventually stops hiding entirely. Around this age, the fawn begins eating solid food but continues to nurse from its mother. The mother and fawn then join a herd. Young female gazelles may stay with their mothers through their first year. Young males may also follow their mothers, but once they reach adolescence territorial males notice them, so they cannot follow their mothers into territories. The mother may follow and stay with her young male, but eventually stops following him when he is driven away; the young male will then join a bachelor group.
