Томсонның газелі түрлері

Species of gazelle

Thomson's gazelle (Eudorcas thomsonii) is one of the best known species of gazelles. It is named after explorer Joseph Thomson and is sometimes referred to as a "tommie". It is considered by some to be a subspecies of the red fronted gazelle and was formerly considered a member of the genus Gazella within the subgenus Eudorcas, before Eudorcas was elevated to genus status. Thomson's gazelles can be found in numbers exceeding 200,000 The relationships between Thomson's gazelle and the congeneric Mongalla gazelle (E. albonotata) remain disputed; while some authors such as Alan W. Gentry of the (Natural History Museum, London) consider the Mongalla gazelle to be a subspecies of Thomson's gazelle, others (such as Colin Groves) consider the Mongalla gazelle to be a full species. Zoologist Jonathan Kingdon treated Heuglin's gazelle, sometimes considered a species of Eudorcas (E. tilonura) or a subspecies of the red fronted gazelle (E. r. tilonura), as a subspecies of Thomson's gazelle. Thomson's gazelle is named after the Scottish explorer Joseph Thomson; the first recorded use of the name dates to 1897. Another common name for the gazelle is "tommy". Antilope, Eudorcas, Gazella, and Nanger form a clade within their tribe Antilopini. A 1999 phylogenetic analysis showed that Antilope is the closest sister taxon to Gazella, although the earliest phylogeny, proposed in 1976, placed Antilope as sister to Nanger. In a more recent revision of the phylogeny of the Antilopini on the basis of nuclear and mitochondrial data in 2013, Eva Verena Bärmann (of the University of Cambridge) and colleagues constructed a cladogram that clearly depicted the close relationship between Nanger and Eudorcas. Antilope and Gazella were found to have a similar relationship. Two subspecies are identified:
E. t. nasalis (Lönnberg, 1908) – Serengeti Thomson's gazelle ranges from the Serengeti to the Kenya Rift Valley. E. t. thomsonii (Günther, 1884) – eastern Thomson's gazelle ranges from east of the Rift Valley in Kenya and Tanzania, southward to Arusha District (Tanzania) and then southwestward to Lake Eyasi, Wembere River, and Shinyanga.

Thomson's gazelle is a relatively small gazelle; it stands at the shoulder. Males weigh , while the slightly lighter females weigh Facial characteristics of the gazelle include white rings around the eyes, black stripes running from a corner of the eye to the nose, rufous stripes running from the horns to the nose, a dark patch on the nose, and a light forehead. The coat is sandy brown to rufous; a black band runs across the flanks, from the upper foreleg to just above the upper hind leg. A buff band occurs above the black stripe. Short, black streaks mark the white rump. The black tail measures Males have well developed preorbital glands near the eyes, which are used for scent marking territories. Both sexes possess horns that curve slightly backward with the tips facing forward. The horns, highly ringed, measure in males and in females. However, females have more fragile horns; some are even hornless. This small antelope can run extremely fast, up to , and zigzag, an adaptation which often saves it from predators. Sometimes, they are also taken by leopards, lions, African wild dogs, hyenas, Nile crocodiles and African rock pythons, and their fawns are sometimes the prey of eagles, jackals, and baboons. A noticeable behaviour of Thomson's gazelles is their bounding leap, known as stotting or pronking, used to startle predators and display strength.

During the wet season, a time when grass is abundant, adult male gazelles graze extensively. They spread out more and establish breeding territories. Younger males usually spend their time in bachelor groups, and are prevented from entering the territories. As the female groups pass through and forage, the territorial males may try to herd them, and are usually successful in preventing single females from leaving, but not whole groups. If a bachelor male should be passing through a territorial male's region, the male will chase the offender out of his territory. Males also mark grass stems with their preorbital glands, which emit a dark secretion. If so, he continues to court and mount her. Birthing predominantly occurs after the rainy season, with newborn fawns weighing They give birth twice yearly with one or two fawns. 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 tissues. As the fawn approaches two months of age, it spends more time with its mother and less time hiding. Eventually, it stops hiding. Compared to some other East African ruminant species that did change their food intake and digestion in response to heat stress, Thomson's gazelle appears relatively well adapted to periodic heat stress. Acacia species are high in tannins, anti nutritional factors that can decrease metabolic performance.

The population estimate is around 550,000. The population had declined 60% from 1978 to 2005. Threats to Thomson's gazelles are habitat modification, fire management, and road development.