The black Rhinoceros, Diceros bicornis (1758)
Phylum : Chordata
Class : Mammalia
Infraclass : Eutheria
Order : Perissodactyla
Family : Rhinocerotidae
Genus : Diceros
Species : D. bicornis
Subspecies : D.b. bicornis †, D.b. brucii †, D.b. chobiensis, D.b. ladoensis, D.b. longipes †, D.b. michaeli, D.b. minor, D.b. occidentalis
- Critically endangered
- 3,8 m long and 1 400 kg (size)
- Southeastern Africa (map)
The rhinoceros originated in the Eocene about fifty million years ago alongside other ungulates (hooved animals). Ancestors of the black and the white rhinoceros were present in Africa by the end of the Late Miocene about ten million years ago. The two species evolved from the common ancestral species Ceratotherium neumayri during this time. The clade comprising the genus Diceros is characterised by an increased adaptation to browsing. Between four and five million years ago, the black rhinoceros diverged from the white rhinoceros. After this split, the direct ancestor of Diceros bicornis, Diceros praecox was present in the Pliocene of East Africa (Ethiopia, Kenya, Tanzania). D. bicornis evolved from this species during the Late Pliocene – Early Pleistocene.
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.
Black rhinoceros are generally thought to be solitary, with the only strong bond between a mother and her calf. In addition, males and females have a consort relationship during mating, also subadults and young adults frequently form loose associations with older individuals of either sex. They are not very territorial and often intersect other rhino territories. Home ranges vary depending on season and the availability of food and water. Generally they have smaller home ranges and larger density in habitats that have plenty of food and water available, and vice versa if resources are not readily available. Sex and age of an individual black rhino influence home range and size, with ranges of females larger than those of males, especially when accompanied by a calf. In the Serengeti home ranges are around 70 to 100 km2, while in the Ngorongoro it is between 2.6 to 58.0 km2. Black rhinos have also been observed to have a certain area they tend to visit and rest frequently called “houses” which are usually on a high ground level. These “home” ranges can vary from 2.6 km2 to 133 km2 with smaller home ranges having more abundant resources than larger home ranges.
Black rhinoceros in captivity and reservations sleep patterns have been recently studied to show that males sleep longer on average than females by nearly double the time. Other factors that play a role in their sleeping patterns is the location of where they decide to sleep. Although they do not sleep any longer in captivity, they do sleep at different times due to their location in captivity, or section of the park.
The black rhino has a reputation for being extremely aggressive, and charges readily at perceived threats. They have even been observed to charge tree trunks and termite mounds. Black rhinos will fight each other, and they have the highest rates of mortal combat recorded for any mammal: about 50% of males and 30% of females die from combat-related injuries. Adult rhinos normally have no natural predators, thanks to their imposing size as well as their thick skin and deadly horns. However, adult black rhinos have fallen prey to crocodiles in exceptional circumstances. Calves and, very seldom, small sub-adults may be preyed upon by lions as well.
Black rhinoceros follow the same trails that elephants use to get from foraging areas to water holes. They also use smaller trails when they are browsing. They are very fast and can get up to speeds of 56 kilometres per hour running on their toes.