Rhinoceroses (family Rhinocerotidaeare) the largest land mammals after the elephant. There are five species of rhinos, two African and three Asian. The African species are the white and black rhinoceroses. Both species have two horns. Asian rhinos include the Indian (or great one-horned rhinoceros) and the Javan, each with one horn, and the Sumatran, which has two.
© Guy Standen
Rhinos are herbivores, meaning they eat only plants. White rhinos, with their square-shaped lips, are ideally suited to graze on grass. Other rhinos prefer to eat the foliage of trees or bushes.
Current estimated populations:
Black Rhino (Diceros bicornis): 2,400.
White Rhino (Ceratotherium simum): 7,500.
Sumatran Rhino (Dicerorhinus sumatrensis): 400.
Javan Rhino (Rhinoceros sondaicus): fewer than 100.
Indian Rhino (Rhinoceros unicornis): more than 2,000.
As solitary creatures, both male and female rhinos establish territories. Males mark and defend their territories. Rhinos use their horns not only in battles for territory or females but also to defend themselves from lions, tigers and hyenas.
Males and females frequently fight during courtship, sometimes leading to serious wounds inflicted by their horns. After mating, the pair go their separate ways. A calf is born 14 to 18 months later. Although they nurse for a year, calves are able to begin eating vegetation one week after birth.
Rhinos rank among the most endangered species on Earth. Valued for their horns, they face a serious threat from poaching. Some cultures believe that the powdered rhino horn will cure everything from fever to food poisoning and will enhance sexual stamina.
Reasons For Hope
The March 2010 CITES  meeting in Doha, Qatar, created new safeguards for some rare wildlife, but left many threatened species in as much trouble as ever. However, for rhinos, there was some good news: countries with rhinos signed an agreement to step up law enforcement and population monitoring to help reduce poaching of dwindling rhino populations.