Rhinoceroses are the largest land mammals after the elephant. There are five species of rhino found in the world with 3 out of the 5 species of rhino now considered to be critically endangered. The rhino is thought to be the second biggest land mammal in the world behind the African elephant. The five species of rhinoceros are the white rhino (which is the largest species of rhino) and the black rhino which are both native to Africa and are only really distinguished in size as they look fairly similar. The Indian rhino, the Sumatran rhino and the Javan rhino are all native to Asia and are much smaller in size than the white rhino and the black rhino of Africa. Black and white rhinos are found in Africa, primarily in the southern and eastern countries. The Sumatran rhino is found in Indonesia and Malaysia. The Javan rhino, once found in a number of Asian countries, today lives only in Indonesia and Vietnam. Similarly, the Indian rhino once roamed across most of the Indian subcontinent, but today is only found in small sections of India and Nepal. 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. The prominent horn for which these rhinos are so well known has also been their downfall. Many animals have been killed for this hard, hair-like growth, which is revered for medicinal use in China, Taiwan, Hong Kong, and Singapore. The horn is also valued in North Africa and the Middle East as an ornamental dagger handle. There are only about 2,000 Indian rhinos left in the wild. Rhinos rank among the most endangered species on Earth. Valued for their horns, they face a dire threat from poaching, which is rapidly pushing them towards extinction. Their horns are used in traditional Chinese medicine, as well as carved into jewelry, dagger handles and other trinkets. Rhino horns have become so valuable on the black market that thieves are stealing them from museums and game trophies shot long ago.