The Javan rhinoceros is amongst the world’s rarest big mammals. It is prehistoric-looking, is a dusky gray color, and has a single horn. Its hairless skin has several loose folds, which look like armor plating. Every Javan rhino lives in Indonesia’s Ujung Kulon National Park, which makes this species even more under threat of extinction. However, the numbers have been slowly increasing over the last five years and the establishment of a second population may soon mean that the species will have much-needed extra capacity. If the rhinos in Java are lost, the species will be extinct.
The Javan rhinoceros lives only in the Ujung Kulon National Park in the very western part of Java. It lives within dense rainforests with plenty of mud wallows and water, preferring low-lying sites.
There are still big gaps in information about Javan rhinos, as they are very difficult to study, and very little is known regarding their social behavior. They are generally solitary animals, except for breeding pairs and mothers with young. Their range extends from 3 to 20 sq m, and various groups have ranges that overlap each other. Javan rhinos sometimes gather in groups at salt-licks and wallows, the latter allowing them to maintain a cool body temperature and helping to prevent parasite infection and disease. The Javan rhinoceros generally do not dig mud wallows themselves, preferring to use those of other animals or naturally occurring pits, enlarging them with their horn. This species is much less vocal compared to related species, and very few vocalizations from Javan rhinos have been recorded.
Javan rhinos live in very dense jungles and they have never been bred in captivity, and so very little information is to hand with regard to their mating system. Pairs form for mating, which might mean that Javan rhinos are polygynous. The mating season is roughly from July through to November. Gestation is for 16 months, and births occur every four to five years. A single rhinoceros is born at one time. A young rhino is active soon after birth. It will be nursed by its mother for up to one to two years. Females reach maturity when they are three to four years old, and males after six years.
The huge decline in Javan rhinoceros numbers has been mostly attributed to being hunted for its horn and other body parts to be used for traditional Chinese medicine. Habitat loss from logging and development has had a big impact on the species, and it has also suffered from disease and natural disasters, either of which could destroy an entire population.
According to the WWF Panda resource, the total population size of the Javan rhino is 63 individuals. Currently, this species is classified as Critically Endangered (CR) on the IUCN Red List.