Only 2 populations of the Javan rhinoceros are known to exist. In the Ujong Kulon National Park in Java (Indonesia) there are about 50 to 60 animals. The 2nd population is in Cat Tien National Park (Vietnam) where only 5 to 10 animals remain.
Javan rhinos measure about 130–150cm in height and can weigh up to 1,500kg. The Rhinoceros sondaicus annamitcus sub-species in Vietnam is considerably smaller than its Ujong Kulon counterparts in Indonesia.
It is generally believed that only the males have a small horn. The horn is actually a dense formation of hair rather than bone. Rhino horn is highly valued as a traditional medicine. However, medical claims for its 'magical' properties have never been scientifically backed up. Hunting and trading in parts of any rhino is forbidden under the international Convention on International Trade in Endangered Species (CITES).
The Javan rhino is a solitary animal. If more than one rhino is seen at the same time, it is usually a female with its young. The gestation period of these rhinos is about 16 months. A young rhino stays with its mother for about 3-4 years. Javan rhinos become sexually mature after 4-6 years.
The Javan rhino is quite adaptable to its environment. It lives in semi-evergreen forests and likes to graze in open grassy areas. In Vietnam, loss of habitat has forced the rhino into a very inhospitable area of steep hills covered with inaccessible bamboo and rattan thickets.
They appear to eat a wide range of plants but their diet is largely unknown. To supplement their diets, they need to consume salt regularly. Therefore, in Ujong Kulon the rhinos drink seawater. In Vietnam, the rhinos are known to frequent a number of saltlicks - springs with mineral rich water. The saltlicks are of crucial importance for this rhino to survive. If the rhino can not get its minerals from the saltlick, it will almost certainly die.
To keep body temperature down rhinos stay out of the sun and like to bathe often in so called wallows. The dried out mud on their skin helps to protect them against dangerous radiation from the sun and also against a range of parasites.
Wallowing is, therefore, very important for rhinos. Wallow sites are also often places where different rhinos meet each other and without them rhinos would find it difficult to find a partner with which to mate.
The footprints of the rhinos in Ujong Kulon and Vietnam are quite different. The ones in Vietnam are much smaller. Scientists estimate that the Vietnamese rhino is about 60 to 70% of the size of its Indonesian relative. Although they are of the same species, scientists believe the populations are so different that they can not be crossbred.
However, this creature is now so rare, and as it is naturally secretive, in fact, very little is known about Javan rhinos, especially the handful that remain in Vietnam.