There are five species of Rhinoceroses (family Rhinocerotidae) in the world, two in Africa and three in tropical Asia. All of them are threatened or endangered. The "classic" rhino in the mind's eye is the Black Rhinoceros Diceros bicornis of Africa (right in a great photo by W. Ed Harper). I have never seen one despite spending a month in Kenya in 1981; quite to our surprise, they had become very rare by then. Poachers decimated Black Rhino populations throughout Africa and today only isolated fragments remain. Ed Harper's shot is from Ngorongoro Crater in northern Tanzania, one of few places left on earth where one still has a reasonable chance to see one (as hopefully I will some day soon).

The Black Rhino is a browser, often more nocturnal than diurnal. Until poachers nearly wiped it out (the horn is sold as dagger scabbards in the Middle East and rhino horn is sold as an aphrodisiac in southeast Asia), this was a very successful species. It once ranged from Somalia to South Africa and thrived in a wide variety of habitats, including montane forests in Kenya and the bleak Kalahari Desert of Namibia and Botswana. There is a fine book about recent research into the life history and survival of Black Rhinos in the Kalahari: Horn of Darkness: Rhinos on the Edge (1997) by Carol Cunningham & Joel Berger [Oxford Univ. Press, New York]. It tells the incredible story of finding and tracking rhinos in this bleak habitat. It also presents their politically incorrect finding that cutting off rhino horns in an attempt to save them was not a successful strategy anywhere that rhinos coexist with hyenas. Mother rhinos require their horns to protect the young from predators.

Both species can have one or two horns. White Rhinos have a long head and lack the more "sway-back" appearance of Black Rhino; they also have less hairy ears. They are the second largest land animal in Africa, after African Elephant. The distribution of White Rhino was always patchy because they require extensive thick grasslands for grazing. They were almost wiped out by hunting a hundred years ago but "Operation Rhino" in the 1970s re-established populations across much of their former range, at least in southern Africa. The environmental project was so successful that the species was no longer consider "endangered." Now it is Black Rhinos that are on the edge of extinction.

The Indian Rhino is very much a swampland species, evolved within the ecology of floodplain grasslands. It is mainly a grazer and can easily disappear into the tall grass. It is aggressive and dangerous and therefore one is restricted to staying within your vehicle in the national park. Our visit to Kaziranga was in the dry season and we did see a half-dozen or so rhinos on each morning or afternoon game drive. Like other rhinos, each male marks its territory with piles of dung, some of which are on the wide dirt roads through the reserve....