Javan Rhinoceros

The Javan rhinoceros (Rhinoceros sondaicus), commonly known as the Sunda rhinoceros or lesser one-horned rhinoceros, is one of only five living rhinoceroses in the family Rhinocerotidae. The Javan rhinoceros scientific name is Rhinoceros sondaicus. The species is only found in Ujung Kulon National Park, a protected area on a short peninsula that stretches from Java's western end. It is related to the Indian rhinoceros and has mosaic, armour-like skin, although it is smaller, measuring 3.1–3.2 m (10–10 ft) in length and 1.4–1.7 m (4.6–5.6 ft) in height (closer in size to the black rhinoceros of the genus Diceros). Its horn is typically less than 25 cm (9.8 in) long and less than those of other rhino species. Only adult males have horns; females are completely devoid of them. 

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Image: Javan Rhinoceros

The Javan rhinoceros was formerly the most widespread of Asian rhinoceroses, ranging from the Indonesian islands of Java and Sumatra through Southeast Asia, India, and China. With only one known natural population and no individuals in captivity, the species is highly endangered. It is possibly the world's rarest big mammal, with only about 74 individuals living in Indonesia's Ujung Kulon National Park on the western tip of the island of Java. In 2011, Vietnam's Cat Tien National Park declared the Javan rhino extinct. 

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Image: Javan Rhino

Poaching, primarily for their horns, which are highly valued in traditional Chinese medicine and cost as much as US$30,000 per kg on the illegal market, is responsible for the decline of the Javan rhinoceros.

Trophy hunting became a severe concern as European presence in their range increased. Habitat loss, particularly as a result of wars in Southeast Asia, such as the Vietnam War, has also contributed to the species' decline and hindered recovery.

Etymology

Rhinoceros is a mixture of two ancient Greek words: ris, which means "nose," and keras, which means "horn of an animal." The name sondaicus comes from the biogeographical region of sunda, which includes the islands of Sumatra, Java, Borneo, and the adjacent smaller islands. The lesser one-horned rhinoceros is another name for the Javan rhino (in contrast with the greater one-horned rhinoceros, another name for the Indian rhino).

Evolution

In the Early Eocene, rhinoceroses are thought to have split from other perissodactyls. Mitochondrial DNA analysis reveals that current rhino ancestors diverged from Equidae ancestors around 50 million years ago. The existing Rhinocerotidae family initially arose in Eurasia during the Late Eocene, and the extant rhino species dispersed from Asia during the Miocene. 

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Image: Different species of Rhino

The only members of the genus Rhinoceros, the Indian and Javan rhinoceros, first appear in the fossil record in Asia during the Early Pleistocene. The species' earliest known record comes from Early Pleistocene (1.5 Ma) deposits in Trinil, Java. According to genetic evidence, the two species split significantly earlier, around 11.7 million years ago. The Indian and Javan rhinoceroses, despite belonging to the same genus, are not thought to be closely related to other rhino species. They may be closely related to the extinct Gaindatherium or Punjabitherium, according to various studies.

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Rhinoceros and the extinct Punjabitherium were classified in the same lineage as Dicerorhinus, the Sumatran rhino, according to a comprehensive cladistic analysis of the Rhinocerotidae. According to other research, the Sumatran rhinoceros is more closely linked to the two African rhinoceros. The Sumatran rhino may have split from the rest of Asian rhinos 15 million years ago, or even 25.9 million years ago (based on mitochondrial data).

Description

The Javan rhinoceros is smaller than the Indian rhinoceros and comparable to the black rhinoceros in size. It is Java's largest animal and Indonesia's second-largest animal after the Asian elephant. The Javan rhino can reach a height of 1.4–1.7 m (4.6–5.6 ft) and a length of 2–4 metres (6.5–13 feet) including its head. Adults have been estimated to weigh between 900 and 2,300 kg (1,980 and 5,070 lb), even though research to obtain precise measurements of the animals has never been done and is not a priority due to their severe conservation status. There is no significant size difference between the genders, but females may be slightly bigger.

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Image: Javan Rhinoceros body parts

Based on photographic evidence and footprint measurements, the rhinos in Vietnam appeared to be significantly smaller than those in Java. The Javan rhinoceros, like the Indian rhino, has a single horn (the other extant species have two horns). Its horn is the shortest of all extant rhinos, measuring less than 20 cm (7.9 in) on average and only 27 cm on occasion (11 in). Horns are only found in males. 

Distribution and Habitat

Even the most optimistic estimate puts the number of Javan rhinos in the wild at less than 100. They are considered one of the world's most endangered animals. Only the Ujung Kulon National Park on Java's western tip is known to be home to the Javan rhinoceros. The animal once roamed eastward through Myanmar, Thailand, Cambodia, Laos, and Vietnam, and southward to the Malay Peninsula and the islands of Sumatra, Java, and possibly Borneo.  The Javan rhino prefers lowland rain forests, grasslands, and reed beds with plenty of rivers, huge floodplains, or wet regions with lots of mud wallow. 

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Image: Javan Rhino Distribution

Despite its preference for low-lying habitats in the past, the subspecies in Vietnam has been driven to much higher terrain (up to 2,000 m or 6,561 ft) due to human encroachment and poaching. For at least 3,000 years, the Javan rhinoceros' range has been shrinking. The rhinoceros' northern range reached into China circa 1000 BC, but it began to migrate southward at a rate of about 0.5 km (0.31 mi) per year as human settlements grew in the area. In India, it most certainly went extinct in the first decade of the twentieth century. By 1932, the Javan rhino had been hunted to extinction on the Malay Peninsula. During World War II, the remaining ones on Sumatra died out.

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Image: A Javan Rhino

Javan Rhinoceros Population

In 2019, the International Rhino Foundation assessed the number of Javan rhinos to be 72 individuals. While this population puts the Javan rhino one of the world's most endangered mammals, it has remained steady for more than 30 years and has grown from an estimated 50 individuals during the last decade. There were three subspecies of Javan rhinoceros in the past. There were also the Indian Javan rhinoceros and the Vietnamese Javan rhinoceros, in addition to the subspecies that persist now. The Indian Javan rhino extinct as well as the Vietnamese Javan rhinoceros are also extinct, hence both are now considered extinct. In Vietnam's Cat Tien park, a small species of Javan rhinos were discovered, however, the only surviving member of the subspecies was discovered poached in 2010.

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Image: State of the Rhino 2020

Javan Rhinoceros Diet

Herbivorous, the Javan rhinoceros feeds on a variety of plant species, including shoots, twigs, young foliage, and fallen fruit. The species prefers plants that thrive in sunny locations such as woodland clearings, shrubland, and other vegetation types with few huge trees. To get to its meal, the rhino smashes down saplings and grabs it with its prehensile top mouth. Of all the rhino species, it is the most versatile feeder. It is currently a pure browser, but it has most likely browsed and grazed in the past. The rhino consumes about 50 kg (110 lb) of food every day. It requires salt in its diet, just as the Sumatran rhino.

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Javan Rhino Predators

In the wild, the Javan rhinoceros has few predators. Ujung Kulon was home to Javan tigers until the 1960s when they were proclaimed extinct. In Ujung Kulon, a small population of Javan leopards survives and may hunt on rhino calves and weaker animals. The rhino's greatest threat today is a lack of genetic variation, which threatens breeding numbers, as there has been no human poaching in the rhino's remaining habitat in the last 25 years.

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Javan Rhino Behaviour

Except for breeding pairs and moms with calves, the Javan rhinoceros is a solitary species. At salt licks and mud wallows, they sometimes cluster in small groups. All rhinos wallowing in mud have a common characteristic that allows them to maintain cool body temperatures while also preventing sickness and parasite infestation. The Javan rhinoceros rarely digs its mud pits, preferring instead to use other animals' pits or naturally formed trenches, which it will enlarge including its horn. Salt licks are particularly significant because salt provides essential nutrients to the rhino. Male house ranges are 12–20 km2 (4.6–7.7 sq mi) bigger than female home ranges, which are 3–14 km2 (1.2–5.4 sq mi). Male domains are less overlapping than female territory.

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There are no reports of territorial fights. Dung piles and urine spraying are used by males to mark their territory. Foot scrapes on the ground and bent saplings appear to be used for communication as well. Other rhino species have a strange habit of defecating in large mounds of rhino dung and then scratching their back feet in it. While defecating in piles, Sumatran and Javan rhinos do not scrape their faeces. This behaviour change is assumed to be ecological; the strategy may not be beneficial for dispersing scents in the wet forests of Java and Sumatra. The Javan rhino is far less vocal than the Sumatran rhino, with only a few recorded sounds. Humans are the only known predators of adults.

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Javan Rhinoceros Facts

• Rawing is the name given to one of the 67 Javan rhinos.

• They're large animals that can weigh up to 2.3 tonnes.

• In the wild, they survive for about 30-45 years.

• They're herbivores, meaning they solely consume plants.

• Except for mating pairs and mothers with young, they are solitary creatures.

• After the Asian elephant, Javan rhinoceros are Indonesia's second-largest animal.

• Dung mounds and urine spraying are used by male Javan rhinos to define their territory.

• Scrapes in the ground made by their feet and twisted saplings seem to be used for communication.

• Poaching due to an overabundance of demand for rhino horn and medicine has been the primary reason for their population reduction. The species was eventually wiped off in Vietnam due to poaching.

• In Ujung Kulon National Park (UKNP), their food source is being taken over by the invasive Arenga palm, but WWF-Australia is working to change that.

Javan Rhinoceros IUCN Status

Rhinoceros unicornis is a species of rhinoceros. The Indian rhino is Asia's largest species of rhinoceros. Vulnerable according to the IUCN. Population ranges between 3,300 to 3,600 people. Tropical grassland, shrubland, and savanna habitats. Moreover, In UKNP, the world's last bastion for the Javan Rhino, an estimated 35-44 rhinos exist.

The four RPUs spend around 200 days a year hiking into the bush, supporting park authorities in their search for rhino poachers. In a typical year, the RPUs in this area will go about 2,000 miles nearly the distance between Madrid and Moscow and will only see a Javan rhino once or twice, if they're lucky. In reality, while on patrol in 2011, no RPU member saw a single rhino. Surprisingly, video camera traps “captured” 35 individually recognisable rhinos, including four young rhinos, in the same year.

The Javan rhinoceros (Rhinoceros sondaicus) is one of three Asian rhino species found only on the Indonesian island of Java. They are considered one of the world's most endangered animals. There has been no human poaching in the rhino's remaining habitat in the last 25 years. The Javan rhinoceros is a solitary species with few predators in the wild. In Ujung Kulon, a small population of Javan leopards survives and may hunt on rhino calves and weaker animals.