Three subspecies are recognized—the Indian Javan Rhino (R. s. inermis), presumed extinct since the 1920s, the Vietnamese Javan Rhino (R. s. annamiticus), declared extinct in 2011, and the only surviving subspecies, the Malaysian Javan Rhino (R. s. sondaicus).
The current population of Javan Rhinos is estimated at fewer than 69 individuals. The Asian Rhino Specialist Group (AsRSG) places the population in the range 65–68 in its briefing document for the CITES Cop 18 meeting set for September 2019.
The historical range of the Javan Rhino is uncertain, but it would have extended across a large part of Southeast Asia. In the far north it would have overlapped with that of the Indian Rhino and in the south with the Sumatran Rhino. It is thought to have once been the most populous of the Asian rhinos, but is now confined to a single location on the Ujung Kulon Peninsula at the far western tip of Java. (See maps)
Today the Javan Rhino is confined to lowland tropical rainforest, especially near water. Historically, however, its habitat would have extended across highland and lowland areas and would have included open mixed forest and grassland.
Weight: 2,000–4,400 lbs (900–2,000 kg) Shoulder height: 4 ft 11 in–5 ft 7 in (1.5–1.7 m) Length nose to tail: 9 ft 10 in–10 ft 6 in (3–3.2 m) Horn length: about 10 in (26 cm) for males and absent or much smaller for females
Males have a single horn while females are often hornless (if present, it is much smaller than that of males). Although it has deeply folded skin, the folds are less pronounced than those of the Indian Rhino. The patterned skin has a scale-like appearance. Like the other Asian rhinos and the Black Rhino of Africa, it has a prehensile upper lip.
Longevity is uncertain, but the Javan Rhino probably lives from 30–40 years in the wild. Not much is known about the detail of its biology, but it is presumed to be similar to that of other rhino species.
Although hundreds of plants species have been recorded as part of the Javan Rhino diet, much comes from the young shoots and twigs of a few favored and common species. In Ujung Kulon National Park, where the only surviving population is found, the Javan Rhino is a browser, but quite likely it was also a grazer in its historical range. As for the other Asian species, salt licks would have been an important source of essential minerals. There are no salt licks in Ujung Kulon, but rhinos have been seen drinking seawater and it has been suggested that this behavior is an attempt to access the minerals they need.
The thick vegetation of its current habitat precludes rapid movement, but in more open habitat it would probably be as mobile as any other rhino species. Like the Indian Rhino, it is also at home in aquatic environments.
The Javan Rhino is not very vocal and seems to rely more on urine and dung, as well as secretions from its foot glands, for communicating with other individuals.
Males and females are solitary except for females with young. They are secretive and seldom seen. Male territories are large and slightly overlap, but unlike other rhino species, they are not aggressively defended. Territories are marked with urine, feces, and scrapes. Female territories are much smaller and overlap considerably. Javan Rhinos love wallowing and spend much time covering themselves in thick mud which helps them to maintain a constant body temperature and to keep biting insects at bay.
As the only population is restricted to a single conservation area, human contact is limited to a few tourists lucky enough to see them and the guards of the park’s Rhino Protection Units.
Listed as “Critically Endangered” on the IUCN Red Data List. Listed on CITES Appendix I.
The tiny population and restricted habitat hold the threat of inbreeding and the consequent loss of genetic diversity. Java, as with the Malaysian Archipelago as a whole, is highly vulnerable to major volcanic eruptions and resultant tsunamis—the early 2019 activity of Anak Krakatau in the Sunda Strait near Ujung Kulon National Park, could have proved disastrous for the Javan Rhino.