Impala

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Impala
Mature male impala in Serengeti National Park, Tanzania
Female impala in Mikumi National Park, Tanzania
Conservation status
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Mammalia
Order:Artiodactyla
Family:Bovidae
Subfamily:Aepycerotinae
Gray, 1872
Genus:Aepyceros
Sundevall, 1847
Species:A. melampus
Binomial name
Aepyceros melampus
(Lichtenstein, 1812)
Subspecies
Distribution of the impala
Red =A. m. melampus
Blue = A. m. petersi
 
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Impala
Mature male impala in Serengeti National Park, Tanzania
Female impala in Mikumi National Park, Tanzania
Conservation status
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Mammalia
Order:Artiodactyla
Family:Bovidae
Subfamily:Aepycerotinae
Gray, 1872
Genus:Aepyceros
Sundevall, 1847
Species:A. melampus
Binomial name
Aepyceros melampus
(Lichtenstein, 1812)
Subspecies
Distribution of the impala
Red =A. m. melampus
Blue = A. m. petersi

The impala (Aepyceros melampus) is a medium-sized African antelope. Its height ranges between 75 and 95 cm (30 and 37 in) and it weighs between 40 and 60 kg (88 and 130 lb).

It is found in savannas and thick bushveld in Kenya, Tanzania, Swaziland, Mozambique, northern Namibia, Botswana, Zambia, Zimbabwe, southern Angola, northeastern South Africa, and Uganda. The capital of Uganda, Kampala, derives its name from the large number of impala that once populated the area. It can be found in numbers of up to two million.[2]

Etymology and taxonomy[edit]

The name impala comes from the Zulu language meaning "gazelle". The scientific name, Aepyceros melampus, is derived from Greek words αιπος aipos ("high"), κερος ceros ("horn") and melas ("black"), pous ("foot").

Historically, taxonomists placed impalas in the same tribe as gazelles, kobs, and hartebeests. However, the impala was subsequently placed in its own tribe, Aepycerotini, which has been elevated to subfamily status.

Up to six subspecies have been described[3][4] although only two are usually distinguished, supported by mitochondrial DNA analysis.[4] These are the Common impala (A. m. melampus) and the Black-faced impala (A. m. petersi).

Only one species of impala exists today, although several fossil species are known, including A. datoadeni from the Pliocene of Ethiopia.[5]

Physical description[edit]

The impala is about 75 and 95 cm (30 and 37 in) tall. The coat is short and glossy, normally reddish-brown in colour (hence the Afrikaans name rooibok, not to be confused with rhebok). It has lighter flanks and a white underbelly with a characteristic "M" marking on the rear.[6]

The impala is sexually dimorphic.[7] The average mass for a male impala is 40 to 75 kg (88 to 170 lb), while females weigh about 30 to 50 kg (66 to 110 lb). The male (ram) has lyre-shaped horns which can reach up to 45–92 cm (18–36 in) in length whereas the female (ewe) lacks horns.[6] Both have distinctive black and white stripes running down the rump and tail.[7] The impala has scent glands covered in the fur of the back feet and sebaceous glands on the head.[8]

The black impala, found in very few places in Africa, is extremely rare. A recessive gene causes the black coloration in these animals.[9]

Ecology[edit]

The impala is an ecotone species "living in light woodland with little undergrowth and grassland of low to medium height".[10] It has an irregular distribution due to dependence on relatively flat lands with good soil drainage and water.[10] While it stays near water in the dry season, it can go weeks without drinking if enough green fodder is available.[10]

The impala is an adaptable forager. It usually switches between grazing and browsing depending on the season. During wet seasons when grasses are fresh, it grazes.[10] During dry seasons, it browses foliage, shoots, forbs, and seeds.[10] It may switch between grazing and browsing depending on the habitat.[11] Leopards, cheetahs, lions and wild dogs prey on the impala.

The impala, like other small- to medium-sized African antelope, has a special dental arrangement on the front lower jaw similar to the toothcomb seen in strepsirrhine primates,[12] which is used during grooming to comb the fur and remove ectoparasites.[13]

Social structure and reproduction[edit]

Females and young form herds of up to 200 individuals. When food is plentiful, adult males will establish territories. Females pass through the territories with the best food resources.[14] Territorial males round up any female herds that enter their grounds,[10][14] and will chase away bachelor males that follow.[10][14] They will even chase away recently weaned males. A male impala tries to prevent any female from leaving his territory. During the dry seasons, territories are abandoned, as herds must travel farther to find food. Large, mixed tranquil herds of females and males form. Young male impalas which have been made to leave their previous herd form bachelor herds of around 30 individuals. Males that are able to dominate their herd are contenders for assuming control of a territory.

The breeding season of the impala, also called the rut, begins toward the end of the wet season in May. The entire affair typically lasts about three weeks. While young are usually born after six to seven months,[15] the mother has the ability to delay giving birth for an additional month if conditions are harsh. When giving birth, the female will isolate herself from the herd,[15] despite numerous attempts by the male to keep her in his territory.[16] The female will keep the fawn in an isolated spot for a few days or even leave it lying out in hiding for a few days, weeks, or more, before returning to the herd.[10] There, the fawn will join a nursery group and will go to its mother only to nurse or when predators are near.[10] Fawns are suckled for four to six months.[10] Males which mature are forced out of the group and will join bachelor herds.[10]

When frightened or startled, the whole herd starts leaping about to confuse their predator. Able to jump distances of more than 10 m (33 ft) and 3 m (9 ft) into the air,[17] threatened impalas will explode in a magnificent spectacle of leaping. Sometimes this is done with the animals holding their leg stiffly and the neck arched downwards, a behaviour known as stotting or pronking. The impala can reach running speeds in a zig-zag of about 60 km/h (37 mph)[17] on average with the peak on 80 km/h (50 mph),[18] to escape its predators. When escaping from predators, it can release a scent from glands on its heels, which can help it stay with the group. This is done by performing a high kick of its hind legs.[19]

Status[edit]

The common impala is one of the most abundant antelopes in Africa, with about one-quarter of the population occurring in protected areas.[1] The largest numbers occur in areas such as the Masai Mara and Kajiado (Kenya); Serengeti, Ruaha and Selous (Tanzania); Luangwa Valley (Zambia); Okavango Delta (Botswana); Hwange, Sebungwe and the Zambezi Valley (Zimbabwe); Kruger National Park (South Africa) and on private farms and conservancies (South Africa, Zimbabwe, Botswana and Namibia).[20] The rare black-faced impala survives in Etosha National Park and private farms in Namibia.[1]

Gallery[edit]

References[edit]

  1. ^ a b c IUCN SSC Antelope Specialist Group (2008). Aepyceros melampus. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 18 January 2009. Database entry includes a brief justification of why this species is of least concern
  2. ^ [1]
  3. ^ Grubb, P. (2005). "Order Artiodactyla". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. p. 673. ISBN 978-0-8018-8221-0. OCLC 62265494. 
  4. ^ a b Nersting, Louise Grau; Arctander, Peter (2001). "Phylogeography and conservation of impala and greater kudu". Molecular Ecology 10 (3): 711–719. doi:10.1046/j.1365-294x.2001.01205.x. 
  5. ^ Geraads, D., et al. (2012). "Pliocene Bovidae (Mammalia) from the Hadar Formation of Hadar and Ledi-Geraru, Lower Awash, Ethiopia". Journal of Vertebrate Paleontology 32 (1): 180–197. doi:10.1080/02724634.2012.632046. 
  6. ^ a b Huffman, Brent. "Impala". Ultimate Ungulate. Retrieved 14 October 2012. 
  7. ^ a b Lundrigan, Barbara. "Sproull, Karen". University of Michigan Museum of Zoology. Animal Diversity Web. Retrieved 14 October 2012. 
  8. ^ Armstrong, project editor, Marian (2007). Wildlife and plants. (3rd ed.). New York: Marshall Cavendish. p. 538-9. ISBN 978-0-7614-7693-1. 
  9. ^ Carnaby, Trevor (2006). Beat about the bush : mammals. Johannesburg: Jacana. p. 39. ISBN 978-1-77009-240-2. 
  10. ^ a b c d e f g h i j k Estes, R. (1991). The Behavior Guide to African Mammals, Including Hoofed Mammals, Carnivores, Primates. Los Angeles, University of California Press. pgs. 158–166
  11. ^ Smithers, R. H. N. (1983) The Mammals of the Southern African Subregion. University of Petoria.
  12. ^ McKenzie, A.A. (1990). "The ruminant dental grooming apparatus". Zoological Journal of the Linnean Society 99 (2): 117–128. doi:10.1111/j.1096-3642.1990.tb00564.x.  edit
  13. ^ Mooring, M.; McKenzie, A.A.; Hart, B.L. (1996). "Grooming in impala: Role of oral grooming in removal of ticks and effects of ticks in increasing grooming rate" (PDF). Physiology & Behavior 59 (4–5): 965–971. doi:10.1016/0031-9384(95)02186-8.  edit
  14. ^ a b c Nowak, R. M. (1991). Walker's mammals of the world. Baltimore, Johns Hopkins University press.
  15. ^ a b Estes, R.D. (1999). The Safari Companion. Rev. Ed. Chelsea Green Publishing Company: White River Junction.
  16. ^ Jarman, M. (1979). "Impala Social Behaviour: Territory, Hierarchy, Mating, and the Use of Space". Beihefte Z. Tierpsychol. 21:1–92.
  17. ^ a b Trek Nature Impala
  18. ^ faunographie mammifères Impala
  19. ^ Impala Facts
  20. ^ East, R. 1999. African Antelope Database 1999. IUCN, Gland, Switzerland and Cambridge, UK.

External links[edit]