Breeding Rhinos

Rhinoceros /raɪˈnɒsərəs/, often abbreviated as rhino, is a group of five extant species of odd-toed ungulates in the family Rhinocerotidae. Two of these species are native to Africa and three to Southern Asia.
Members of the rhinoceros family are characterized by their large size (they are some of the largest remaining megafauna, with all of the species able to reach one tonne or more in weight); as well as by an herbivorous diet; a thick protective skin, 1.5--5 cm thick, formed from layers of collagen positioned in a lattice structure; relatively small brains for mammals this size (400--600 g); and a large horn. They generally eat leafy material, although their ability to ferment food in their hindgut allows them to subsist on more fibrous plant matter, if necessary. Unlike other perissodactyls, the two African species of rhinoceros lack teeth at the front of their mouths, relying instead on their powerful premolar and molar teeth to grind up plant food.
Rhinoceros are killed by humans for their horns, which are bought and sold on the black market, and which are used by some cultures for ornamental or traditional medicinal purposes. East Asia, specifically Vietnam, is the largest market for rhino horns. Rhino horns cost as much as gold on the black market. People grind up the horns and then consume them believing the dust has therapeutic properties. The horns are made of keratin, the same type of protein that makes up hair and fingernails. Both African species and the Sumatran rhinoceros have two horns, while the Indian and Javan rhinoceros have a single horn.
The IUCN Red List identifies three of the species as critically endangered.

The word rhinoceros is derived through Latin from the Ancient Greek: ῥῑνόκερως, which is composed of ῥῑνο- (rhino-, "nose") and κέρας (keras, "horn"). The plural in English is rhinoceros or rhinoceroses. The collective noun for a group of rhinoceroses is crash or herd.
The five living species fall into three categories. The two African species, the white rhinoceros and the black rhinoceros, belong to the Dicerotini group, which originated in the middle Miocene, about 14.2 million years ago. The species diverged during the early Pliocene (about 5 million years ago). The main difference between black and white rhinos is the shape of their mouths -- white rhinos have broad flat lips for grazing, whereas black rhinos have long pointed lips for eating foliage.
There are two living Rhinocerotini species, the Indian rhinoceros and the Javan rhinoceros, which diverged from one another about 10 million years ago. The Sumatran rhinoceros is the only surviving representative of the most primitive group, the Dicerorhinini, which emerged in the Miocene (about 20 million years ago). The extinct woolly rhinoceros of northern Europe and Asia was also a member of this tribe.
A subspecific hybrid white rhino (Ceratotherium s. simum × C. s. cottoni) was bred at the Dvůr Králové Zoo (Zoological Garden Dvur Kralove nad Labem) in the Czech Republic in 1977. Interspecific hybridisation of black and white rhinoceros has also been confirmed.
While the black rhinoceros has 84 chromosomes (diploid number, 2N, per cell), all other rhinoceros species have 82 chromosomes.

There are two subspecies of white rhino: the southern white rhinoceros (Ceratotherium simum simum) and the northern white rhinoceros (Ceratotherium simum cottoni). In 2007, the southern subspecies had a wild population of 17,480 (IUCN2008) -- 16,266 of which were in South Africa -- making them the most abundant rhino subspecies in the world. However, the northern subspecies was critically endangered, with as few as four individuals in the wild; the possibility of complete extinction in the wild having been noted since June 2008. Six are known to be held in captivity, two of which reside at the San Diego Zoo Safari Park. Four born in a zoo in the Czech Republic were transferred to a wildlife refuge in Kenya in December 2009, in an effort to have the animals reproduce and save the subspecies.
There is no conclusive explanation of the name white rhinoceros. A popular theory that "white" is a distortion of either the Afrikaans word wyd or the Dutch word wijd (or its other possible spellings whyde, weit, etc.,) meaning wide and referring to the rhino's square lips is not supported by linguistic studies.