The black rhinoceros (Diceros bicornis), also called the black rhino or the hooked-lip rhinoceros, is a species of rhinoceros native to East and Southern Africa, including Angola, Botswana, Eswatini, Kenya, Lesotho, Malawi, Mozambique, Namibia, South Africa, Tanzania, Zambia, and Zimbabwe. Although the species is referred to as black, its colours vary from brown to grey. It is the only extant species of the genus Diceros.
The other rhinoceros native to Africa is the white rhinoceros (Ceratotherium simum). The word "white" in the name "white rhinoceros" is often said to be a misinterpretation of the Afrikaans word (Dutch ) meaning wide, referring to its square upper lip, as opposed to the pointed or hooked lip of the black rhinoceros. These species are now sometimes referred to as the square-lipped (for white) or hook-lipped (for black) rhinoceros.White rhinoceros , Animal Corner
The species overall is classified as critically endangered (even though the south-western black rhinoceros is classified as near threatened) and is threatened by multiple factors including poaching and habitat reduction. Three subspecies have been declared extinct, including the western black rhinoceros, which was declared extinct by the International Union for Conservation of Nature (IUCN) in 2011.Knight, Matthew (10 November 2011) Western black rhino declared extinct . Us.cnn.com. The IUCN estimates that 3,142 mature individuals remain in the wild.
Taxonomy The species was first named Rhinoceros bicornis by Carl Linnaeus in the 10th edition of his Systema naturae in 1758. The name means "double-horned rhinoceros". There is some confusion about what exactly Linnaeus conceived under this name as this species was probably based upon the skull of a single-horned Indian rhinoceros (Rhinoceros unicornis), with a second horn artificially added by the collector. Such a skull is known to have existed and Linnaeus even mentioned India as origin of this species. However he also referred to reports from early travellers about a double-horned rhino in Africa and when it emerged that there is only one, single-horned species of rhino in India, Rhinoceros bicornis was used to refer to the African rhinos (the white rhino only became recognised in 1812). In 1911 this was formally fixed and the Cape of Good Hope officially declared the type locality of the species. Biostor .
Subspecies The intraspecific variation in the black rhinoceros has been discussed by various authors and is not finally settled. The most accepted scheme considers seven or eight subspecies, of which three became extinct in historical times and one is on the brink of extinction:
Southern black rhinoceros or Cape black rhinoceros (D. b. bicornis) – Extinct. Once abundant from the Cape of Good Hope to Transvaal, South Africa and probably into the south of Namibia, this was the largest subspecies. It became extinct due to excessive hunting and habitat destruction around 1850. North-eastern black rhinoceros (D. b. brucii) – Extinct. Formerly central Sudan, Eritrea, northern and southeastern Ethiopia, Djibouti and northern and southeastern Somalia. Relict populations in northern Somalia vanished during the early 20th century. Chobe black rhinoceros (D. b. chobiensis) – A local subspecies restricted to the Chobe Valley in southeastern Angola, Namibia (Zambezi Region) and northern Botswana. Nearly extinct, possibly only one surviving specimen in Botswana. Uganda black rhinoceros (D. b. ladoensis) – Former distribution from South Sudan, across Uganda into western Kenya and southwesternmost Ethiopia. Black rhinos are considered extinct across most of this area and its conservational status is unclear. Probably surviving in Kenyan reserves. Western black rhinoceros (D. b. longipes) – Extinct. Once lived in South Sudan, northern Central African Republic, southern Chad, northern Cameroon, northeastern Nigeria and south-eastern Niger. The range possibly stretched west to the Niger River in western Niger, though this is unconfirmed. The evidence from Liberia and Burkina Faso mainly rests upon the existence of indigenous names for the rhinoceros. A far greater former range in West Africa as proposed earlier is doubted by a 2004 study. The last known wild specimens lived in northern Cameroon. In 2006 an intensive survey across its putative range in Cameroon failed to locate any, leading to fears that it was extinct in the wild. On 10 November 2011 the IUCN declared the western black rhinoceros extinct. Eastern black rhinoceros (D. b. michaeli) – Had a historical distribution from South Sudan, Uganda, Ethiopia, down through Kenya into north-central Tanzania. Today, its range is limited primarily to Kenya, Rwanda and Tanzania. In addition, its population is in South Africa's Addo Elephant National Park. South-central black rhinoceros (D. b. minor) – Most widely distributed subspecies, characterised by a compact body, proportionally large head and prominent skin-folds. Ranged from north-eastern South Africa (KwaZulu-Natal) to northeastern Tanzania and southeastern Kenya. Preserved in reserves throughout most of its former range but probably extinct in eastern Angola, southern Democratic Republic of Congo and possibly Mozambique. It went extinct but reintroduced in Malawi, Botswana, and Zambia. It also ranges in parts of Namibia and inhabit national parks in South Africa. South-western black rhinoceros (D. b. occidentalis) – A small subspecies, adapted to survival in desert and semi-desert conditions. Originally distributed in north-western Namibia and southwestern Angola, today restricted to wildlife reserves in Namibia with sporadic sightings in Angola. These populations are often referred to D. b. bicornis or D. b. minor, but some experts consider them a subspecies in their own right.
The most widely adopted alternative scheme only recognizes five subspecies or "eco-types": D. b. bicornis, D. b. brucii, D. b. longipes, D. b. michaeli, and D. b. minor. This concept is also used by the IUCN, listing three surviving subspecies and recognizing D. b. brucii and D. b. longipes as extinct. The most important difference to the above scheme is the inclusion of the extant southwestern subspecies from Namibia in D. b. bicornis instead of in its own subspecies, whereupon the nominal subspecies is considered extant.
Evolution The rhinoceros originated in the Eocene about fifty million years ago alongside other members of Perissodactyla."Mammals." EDGE of Existence. N.p., n.d. Web. 23 October 2013. The last common ancestor of living rhinoceroses belonging to the subfamily Rhinocerotinae is suggested to have lived around 16 million years ago.
The white rhinoceros and black rhinoceros are more closely related to each other than to other living rhinoceroses. Rhinoceroses closely related to the black and the white rhinoceros were present in Africa by the Late Miocene about 10 million years ago, and possibly as early as 17 million years ago. The two species may have descended from the Eurasian species "Ceratotherium" neumayri, but this is disputed. A 2021 genetic analysis estimated the split between the white and black rhinoceros at around 7 million years ago. After this split, the direct ancestor of Diceros bicornis, Diceros praecox was present in the Pliocene of East Africa (Ethiopia, Kenya, Tanzania). D. bicornis is suggested to have evolved from this species during the Late Pliocene – Early Pleistocene, with the oldest definitive record at the Pliocene–Pleistocene boundary c. 2.5 million years ago at Koobi Fora, Kenya.Geraads, D., 2010. Rhinocerotidae , in: Werdelin, L., Sanders, W.J. (eds), Cenozoic mammals of Africa. University of California Press, Berkeley, pp. 669–683
A cladogram showing the relationships of recent and Late Pleistocene rhinoceros species (minus Stephanorhinus hemitoechus) based on whole nuclear genomes, after Liu et al., 2021:
Description
An adult black rhinoceros stands high at the shoulder and is in length.Black Rhinoceros , Arkive An adult typically weighs from , however unusually large male specimens have been reported at up to . The cows are smaller than the bulls. Two horns on the skull are made of keratin with the larger front horn typically long, exceptionally up to .
The longest known black rhinoceros horn measured nearly in length. Sometimes a third, smaller horn may develop. These horns are used for defense, intimidation, and digging up roots and breaking branches during feeding. The black rhino is smaller than the white rhino and close in size to the Javan rhino of Indonesia. It has a pointed and prehensile upper lip, which it uses to grasp leaves and twigs when feeding, whereas the white rhinoceros has square lips used for eating grass. The black rhinoceros can also be distinguished from the white rhinoceros by its size, smaller skull, and ears; and by the position of the head, which is held higher than the white rhinoceros, since the black rhinoceros is a browser and not a grazer.
Their thick-layered skin helps to protect black rhinos from thorns and sharp grasses. Their skin harbors external parasites, such as mites and ticks, which may be eaten by oxpeckers and egrets. Such behaviour was originally thought to be an example of mutualism, but recent evidence suggests that oxpeckers may be parasites instead, feeding on rhino blood. It is commonly assumed that black rhinos have poor eyesight, relying more on hearing and smell. However, studies have shown that their eyesight is comparatively good, at about the level of a rabbit. Their ears have a relatively wide rotational range to detect sounds. An excellent sense of smell alerts rhinos to the presence of predators.
Distribution
Prehistorical range As with many other components of the African large mammal fauna, black rhinos probably had a wider range in the northern part of the continent in prehistoric times than today. However this seems to have not been as extensive as that of the white rhino. Unquestionable fossil remains have not yet been found in this area and the abundant petroglyphs found across the Sahara desert are often too schematic to unambiguously decide whether they depict black or white rhinos. Petroglyphs from the Eastern Desert of southeastern Egypt relatively convincingly show the occurrence of black rhinos in these areas in prehistoric times.
Historical and extant range The natural range of the black rhino included most of southern and eastern Africa, except the Congo Basin, the tropical rainforest areas along the Bight of Benin, the Ethiopian Highlands, and the Horn of Africa. Its former native occurrence in the extremely dry parts of the Kalahari Desert of southwestern Botswana and northwestern South Africa is uncertain. It was abundant in an area stretching from Eritrea and Sudan through South Sudan to southeastern Niger, especially around Lake Chad. Its occurrence further to the west is questionable, although this is often claimed in literature. Today it is found only in protected nature reserves, having vanished from many countries in which it once thrived, especially in the west and north of its former range. The remaining populations are highly scattered. Some specimens have been relocated from their habitat to better protected locations, sometimes across national frontiers. The black rhino has been successfully reintroduced to Malawi since 1993, where it became extinct in 1990. Similarly it was reintroduced to Zambia (North Luangwa National Park) in 2008, where it had become extinct in 1998, and to Botswana (extinct in 1992, reintroduced in 2003).
In May 2017, 18 eastern black rhinos were translocated from South Africa to the Akagera National Park in Rwanda. The park had around 50 rhinos in the 1970s but the numbers dwindled to zero by 2007. In September 2017, the birth of a calf raised the population to 19. The park has dedicated rhino monitoring teams to protect the animals from poaching.