Diceros bicornis (Linnaeus, 1758)
INTRODUCTION
The Black Rhinoceros Diceros bicornis is basically grey, but the colour varies from yellow-brown to dark brown according to local soil conditions. It has two horns, although occasionally a third small posterior horn is present. The anterior horn is larger than the posterior, averaging 50 cm in length.13 Distinguishable from the White Rhino mainly by the protruding upper lip, (hence the alternative name of hook-lipped rhino), it is not always darker in colour. The Black Rhino is a browser using its upper lip to feed on regenerating twigs of woody growth and legumes.13
Black Rhinos are essentially solitary, but temporary aggregations of up to a dozen individuals have been observed, with longer term associations often forming between mothers and daughters. Breeding takes place throughout the year, although peaks in breeding activity occur at varying times in different range countries. Reproductive maturity is reached at 4 to 6 years in females and 7 to 9 years in males. The gestation period is between 419 and 478 days with an interval of 2.5 to 3.5 years between calves.13
The Black Rhino is the only species of Diceros. There are four recognized subspecies or "ecotypes" and under the new IUCN criteria for level of threat, all four are listed as "critically endangered". The Southern-central Black Rhino (D.b. minor), the most numerous subspecies, inhabited a historic range from central Tanzania down through Zambia, Zimbabwe and Mozambique to northern and eastern South Africa. The South-western Black Rhino (D.b. bicornis) is more adapted to the arid and semi-arid savannas of Namibia, southern Angola, western Botswana and western South Africa. The East African Black Rhino (D.b. michaeli) which had a historic distribution from south Sudan, Ethiopia, Somalia down through Kenya into north-central Tanzania, maintains its current stronghold in Kenya. The West African Black Rhino (D.b. longipes) is the rarest and most endangered subspecies. Whereas it once occurred across most of savanna West Africa, today only a few individuals remain in northern Cameroon.
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