Two of the world's five rhinoceros species are found in Africa, the white rhino (Ceratotherium simum) and the black rhino (Diceros bicornis). Both are victims of illegal hunting, which is done for the sole purpose of obtaining their horns. Rhino horn is used to concoct traditional medicines in Asia and to produce ceremonial dagger handles in certain Middle Eastern countries. At the beginning of the 20th Century, the white rhino was perhaps the most endangered of the five rhino species, having been reduced to only a handful of animals, but its numbers have rebounded incredibly to a population of more than 11,000, thanks to successful conservation efforts both in captivity and in the wild, and the species is no longer considered threatened. The black rhino, by comparison, has been seriously reduced in numbers to only a few thousand individuals in Africa's Miombo-Mopane Wilderness region and is listed as Critically Endangered by IUCN-The World Conservation Union.
In response to the critical situation facing Africa's black rhino, the Houston Zoo has joined with the International Rhino Foundation to support the return of this species to Botswana, a country in which it used to occur, but from which it has been extirpated (wiped out).
