Javan rhinoceros

The Javan rhinoceros (Rhinoceros sondaicus), also called Javan rhino, Sunda rhinoceros and lesser one-horned rhinoceros is a critically endangered member of the genus Rhinoceros of the family Rhinocerotidae, and one of the five remaining extant rhinoceros species. It has a plate-like skin with protective folds and is one of the smallest rhinoceros species with a body length of 3.1–3.2 m (10.2–10.5 ft) and a 1.4–1.7 m (4.6–5.6 ft) long tail. The heaviest specimens weigh around 2,300 kg (5,100 lb). Its horn is usually shorter than 25 cm (9.8 in). Until the mid-19th to about the early 20th century, the Javan rhinoceros had ranged beyond the islands of Java and Sumatra and onto the mainland o...

Fossil remains of Javan rhinoceros have been found at the Neolithic site of Hemudu in Zhejiang, China, and the 4th century BCE Classic of Mountains and Seas appears to describe one living in the Yangtze River basin. Remains were also found in the Tam Hay Marklot cave site in northeastern Laos that date to the Pleistocene. Historically, Javan rhinoceroses were widespread from Assam and Bengal, eastward to Myanmar, Thailand, Cambodia, Laos, Vietnam, and southwards to the Malay Peninsula and the islands of Sumatra, Java, and Borneo. Today, the species only occurs in Ujung Kulon National Park in southwestern Java, where fewer than 100 individuals are estimated to survive. The range of the Javan rhinoceros has been shrinking for at least 3,000 years. Starting around 1000 BC, the northern range of the rhinoceros extended into China, but began moving southward at roughly 0.5 km (0.31 mi) per year, as human settlements increased in the region. It likely became locally extinct in India in the first decade of the 20th century. The Javan rhino was hunted to extinction on the Malay Peninsula by 1932. The last ones on Sumatra are thought to have died during World War II; it may have also been present on Borneo, but these specimens could have been Sumatran rhinocerosses, a small population which still lives there. The Javan rhinoceros was sighted in the Sunderbans between 1630 and 1908, but only six were thought to have survived by 1892. By the end of the Vietnam War, the Vietnamese rhinoceros was thought extinct across all of mainland Asia. Local hunters and woodcutters in Cambodia claim to have seen Javan rhinos in the Cardamom Mountains, but surveys of the area have failed to find any evidence. In the late 1980s, a small population was found in the Cat Tien area of Vietnam, but the last known individual of that population was shot in 2010. The population in Vietnam's Cat Tien National Park was declared locally extinct in 2011. The Javan rhinoceros primarily inhabits dense, lowland rain forests, grasslands, and reed beds with abundant rivers, large floodplains, or wet areas with many mud wallows. Although it historically preferred low-lying areas, the subspecies in Vietnam was pushed onto much higher ground (up to 2,000 m or 6,561 ft), probably because of human encroachment and poaching.

India

The Javan rhinoceros is herbivorous, eating diverse plant species, especially shoots, twigs, young foliage, and fallen fruit. Most of the plants favored by the species grow in sunny areas in forest clearings, shrubland, and other vegetation types with no large trees. The rhino knocks down saplings to reach its food and grabs it with its prehensile upper lip. It is the most adaptable feeder of all the rhino species. Currently, it is a pure browser, but probably once both browsed and grazed in its historical range. The rhino eats an estimated 50 kg (110 lb) of food daily. Like the Sumatran rhino, it needs salt in its diet. The salt licks common in its historical range do not exist in Ujung Kulon, but the rhinos there have been observed drinking seawater, likely for the same nutritional need.

The Javan rhinoceros is a solitary animal with the exception of breeding pairs and mothers with calves. They sometimes congregate in small groups at salt licks and mud wallows. Wallowing in mud is a common behavior for all rhinos; the activity allows them to maintain cool body temperatures and helps prevent disease and parasite infestation. The Javan rhinoceros does not generally dig its own mud wallows, preferring to use other animals' wallows or naturally occurring pits, which it uses its horn to enlarge. Salt licks are also very important because of the essential nutrients the rhino receives from the salt. Bull home ranges are larger at 12–20 km2 (4.6–7.7 sq mi) compared to the cow, which are around 3–14 km2 (1.2–5.4 sq mi). Bull territories overlap each other less than those of the cow. Whether territorial fights occur is unknown. Bulls mark their territories with dung piles and by urine spraying. Scrapes made by the feet in the ground and twisted saplings also seem to be used for communication. Members of other rhino species have a peculiar habit of defecating in massive rhino dung piles and then scraping their back feet in the dung. The Sumatran and Javan rhinos, while defecating in piles, do not engage in the scraping. This adaptation in behavior is thought to be ecological; in the wet forests of Java and Sumatra, the method may not be useful for spreading odors. The Javan rhino is much less vocal than the Sumatran; very few Javan rhino vocalizations have ever been recorded. Adults have no known predators other than humans. The species, particularly in Vietnam, is skittish and retreats into dense forests whenever humans are near. Though a valuable trait from a survival standpoint, it has made the rhinos difficult to study. Nevertheless, when humans approach too closely, the Javan rhino becomes aggressive and will attack, stabbing with the incisors of its lower jaw while thrusting upward with its head. Its comparatively antisocial behavior may be a recent adaptation to population stresses; historical evidence suggests they, like other rhinos, were once more gregarious.

Rhinoceros sondaicus was the scientific name used by Anselme Gaëtan Desmarest in 1822 for a rhinoceros from Java sent by Pierre-Médard Diard and Alfred Duvaucel to the National Museum of Natural History, France. In the 19th century, several zoological specimens of hornless rhinoceroses were described: Rhinoceros inermis proposed by René Lesson in 1838 was a female rhinoceros without horns shot in the Sundarbans. Rhinoceros nasalis and Rhinoceros floweri proposed by John Edward Gray in 1867 were two rhinoceros skulls from Borneo and one from Sumatra, respectively. Rhinoceros annamiticus proposed by Pierre Marie Heude in 1892 was a specimen from Vietnam. As of 2005, three Javan rhinoceros subspecies are considered valid taxa: R. s. sondaicus, the nominate subspecies, known as the Indonesian Javan rhinoceros R. s. inermis, known as the Indian Javan rhinoceros or lesser Indian rhinoceros R. s. annamiticus, known as the Vietnamese Javan rhinoceros or Vietnamese rhinoceros Javan rhinos are smaller than the Indian rhinoceros, and are close in size to the black rhinoceros. They are the largest animal in Java and the second-largest animal in Indonesia after the Asian elephant. The length of a Javan rhino including its head is 2 to 4 m (6.6 to 13.1 ft), and it can reach a height of 1.4–1.7 m (4.6–5.6 ft). Adults are variously reported to weigh between 900 and 2,300 kg (2,000 and 5,100 lb), although a study to collect accurate measurements of the animals has never been conducted and is not a priority because of their extreme conservation status. No substantial size difference is seen between genders, but cows may be slightly bigger. The rhinos in Vietnam appeared to be significantly smaller than those in Java, based on studies of photographic evidence and measurements of their footprints. Like the Indian rhino, the Javan rhino has a single horn (the other extant species have two horns). Its horn is the smallest of all extant rhinos, usually less than 20 cm (7.9 in) with the longest recorded only 27 cm (11 in). Only bulls have horns. Cows are the only extant rhinos that remain hornless into adulthood, though they may develop a tiny bump of an inch or two in height. Javan rhinos do not appear to often use their horns for fighting, but instead use them to scrape mud away in wallows, to pull down plants for eating, and to open paths through thick vegetation. Similar to the other browsing species of rhino (black and Sumatran), the Javan rhino has a long, pointed, upper lip, which helps in grabbing food. The lower incisors are long and sharp; when Javan rhinos fight, they use these teeth. Behind the incisors, two rows of six low-crowned molars are used for chewing coarse plants. Like all rhinos, Javan rhinos smell and hear well, but have very poor vision. They are estimated to live for 30 to 45 years. Their hairless, splotchy gray, or gray-brown skin falls in folds to the shoulder, back, and rump. The skin has a natural mosaic pattern, which lends the rhino an armored appearance. The neck folds of Javan rhinoceros are smaller than those of the Indian rhinoceros, but still form a saddle shape over the shoulders. Because of the risks of interfering with such an endangered species, however, Javan rhinos are primarily studied through fecal sampling and camera traps. They are rarely encountered, observed, or measured directly.

The main factor in the continued decline of the Javan rhinoceros population has been poaching for horns, a problem that affects all rhino species. The horns have been a traded commodity for more than 2,000 years in China, where they are believed to have healing properties. Historically, the rhinoceros' hide was used to make armor for Chinese soldiers, and some local tribes in Vietnam believed the hide could be used to make an antidote for snake venom. Because the rhinoceros' range encompasses many areas of poverty, convincing local people not to kill a seemingly (otherwise) useless animal which could be sold for a large sum of money has been difficult. When the Convention on International Trade in Endangered Species of Wild Fauna and Flora first went into effect in 1975, the Javan rhinoceros was listed under Appendix I, meaning commercial international trade in the Javan rhinoceros and products derived from it is prohibited. Surveys of the rhinoceros horn black market have determined that Asian rhinoceros horn fetches a price as high as $30,000 per kg, three times the value of African rhinoceros horn. Loss of habitat because of agriculture has also contributed to its decline, though this is no longer as significant a factor because the rhinoceros only lives in one nationally protected park. Deteriorating habitats have hindered the recovery of rhino populations that fell victim to poaching. Even with all the conservation efforts, the prospects for their survival are grim. Because the population is restricted to one small area, they are very susceptible to disease and inbreeding depression. Conservation geneticists estimate a population of 100 rhinos would be needed to preserve the genetic diversity of this conservation-reliant species.

The generic name Rhinoceros is a combination of the ancient Greek words ῥίς (ris) meaning nose and κέρας (keras) meaning horn of an animal. The specific name sondaicus is derived from sunda, the biogeographical region that comprises the islands of Sumatra, Java, Borneo, and surrounding smaller islands. The Javan rhino is also known as the lesser one-horned rhinoceros (in contrast with the greater one-horned rhinoceros, another name for the Indian rhino). The Javan rhinoceros occurred in Cambodia in the past and at least three depictions of rhinos are in the bas reliefs of the temple at Angkor Wat. The west wing of the North Gallery has a relief that shows a rhino mounted by a god thought to be the fire god Agni. The rhinos are thought to be Javan rhinoceros rather than the somewhat similar-looking one-horned Indian rhino on the basis of the skinfold on the shoulder that continues along the back in the Javan to give a saddle-like appearance. A depiction of the rhino in the east wing of the South Gallery shows a rhino attacking the damned in the panel depicting heaven and hell. An architect of the temple is thought to have been an Indian Brahmin priest named Divakarapandita (1040–1120 AD) who served king Jayavarman VI, Dharanindravarman I, as well as Suryavarman II, who constructed the temple. The Indian priest who died before the construction of the temple is thought to have influenced the use of tubercles on the skin, which are based on the Indian rhino, while the local Khmer artisans carved the other details of the rhinos based on the more familiar local Javan rhino. The association of the rhinoceros as the vahana of the god Agni is unique to Khmer culture. Another rhinoceros carving in the middle of a circular arrangement in a column with other circles containing elephants and water buffalo is known from the temple of Ta Prohm. Based on anachronistic speculation, it might represent a stegosaur due to the leaves behind it that give the impression of plates. The mascot of the 2023 FIFA U-20 World Cup is a Javan rhinoceros named Bacuya.