Indian rhinoceros

The Indian rhinoceros, also known as the greater one-horned rhinoceros, great Indian rhinoceros or Indian rhino, is a rhinoceros species native to the Indian subcontinent. It is the second largest living rhinoceros and the largest in Asia, with adult males weighing and adult females. Its thick skin is grey-brown with pinkish skin folds. It has a single horn on its snout that grows up to long. Its upper legs and shoulders are covered in wart-like bumps, and it is nearly hairless aside from the eyelashes, ear fringes and tail brush.
The Indian rhinoceros occurs in the Indo-Gangetic Plain in 12 protected areas in northern India and southern Nepal. It is a grazer, eating mainly grass, but also twigs, leaves, branches, shrubs, flowers, fruits and aquatic plants. It is a largely solitary animal, only associating in the breeding season and when rearing calves. Females give birth to a single calf after a gestation of 15.7 months. The birth interval is 34–51 months. Captive individuals can live up to 47 years. It is susceptible to diseases such as anthrax, and those caused by parasites such as leeches, ticks and nematodes.
The Indian rhinoceros is listed as Vulnerable on the IUCN Red List, as the population is fragmented and restricted to less than. Excessive hunting and agricultural development reduced its range drastically. In the early 1990s, the global population was estimated at between 1,870 and 1,895 individuals. Since then, the population increased due to conservation measures taken by the governments. As of March 2025, it was estimated to comprise 4,075 individuals. However, poaching remains a continuous threat.

Taxonomy

Rhinoceros unicornis was the scientific name used by Carl Linnaeus in 1758 who described a rhinoceros with one horn. As type locality, he indicated Africa and India. He described two species in India, the other being Rhinoceros bicornis, and stated that the Indian species had two horns, while the African species had only one.
The Indian rhinoceros is a single species. Several specimens were described since the end of the 18th century under different scientific names, which are all considered synonyms of Rhinoceros unicornis today:

R. indicus by Cuvier, 1817
R. asiaticus by Blumenbach, 1830
R. stenocephalus by Gray, 1867
R. jamrachi by Sclater, 1876
R. bengalensis by Kourist, 1970
Etymology

The generic name rhinoceros is derived through Latin from the, which is composed of wikt:ῥίς#Ancient Greek and wikt:κέρας#Ancient Greek with a horn on the nose. The name has been in use since the 14th century. The Latin word ūnicornis means "one-horned".

Evolution

Ancestral rhinoceroses first diverged from other perissodactyls in the Early Eocene. Mitochondrial DNA comparison suggests the ancestors of modern rhinos split from the ancestors of Equidae around 50 million years ago. The extant family, the Rhinocerotidae, first appeared in the Late Eocene in Eurasia, and the ancestors of the extant rhino species dispersed from Asia beginning in the Miocene. The last common ancestor of living rhinoceroses belonging to the subfamily Rhinocerotinae is suggested to have lived around 16 million years ago, with the ancestors of the genus Rhinoceros diverging from the ancestors of other living rhinoceroses around 15 million years ago. The genus Rhinoceros has been found to be overall slightly more closely related to the Sumatran rhinoceros than to living African rhinoceroses, though there appears to have been gene flow between the ancestors of living African rhinoceroses and the genus Rhinoceros, as well as between the ancestors of the genus Rhinoceros and the ancestors of the woolly rhinoceros and Stephanorhinus.
A cladogram showing the relationships of recent and Late Pleistocene rhinoceros species based on whole nuclear genomes, after Liu et al., 2021:
The earliest fossils of the genus Rhinoceros date to the Late Miocene, around 8–9 million years ago. The divergence between the Indian and Javan rhinoceros is estimated to have occurred around 4.3 million years ago. The earliest representatives of the modern Indian rhinoceros appeared during the Early Pleistocene. Fossils indicate that the Indian rhinoceros during the Pleistocene also inhabited areas considerably further east of its current distribution, including mainland Southeast Asia, South China and the island of Java, Indonesia. They also appear to have ranged as far south as Tamil Nadu in India, based on subfossil remains as recent as the Neolithic. A Late Pleistocene-aged partial fossil skeleton of R. unicornis was described from Kanchanaburi, Thailand in 2018.
Several fossil Rhinoceros species from South Asia, such as R. palaeindicus & R. sivalensis, R. deccanensis and R. namadicus are potentially synonymous with R. unicornis''.

Characteristics

Indian rhinos have a thick grey-brown skin with pinkish skin folds and one horn on their snout. Their upper legs and shoulders are covered in wart-like bumps. They have very little body hair, aside from eyelashes, ear fringes and tail brush. Bulls have huge neck folds. The skull is heavy with a basal length above and an occiput above. The nasal horn is slightly back-curved with a base of about by that rapidly narrows until a smooth, even stem part begins about above base. In captive animals, the horn is frequently worn down to a thick knob. The Indian rhino's single horn is present in both bulls and cows, but not on newborn calves. The horn is pure keratin, like human fingernails, and starts to show after about six years. In most adults, the horn reaches a length of about, but has been recorded up to in length and in weight.
Among terrestrial land mammals native to Asia, Indian rhinos are second in size only to the Asian elephant. They are also the second-largest living rhinoceros, behind only the white rhinoceros. Bulls have a head and body length of with a shoulder height of, while cows have a head and body length of and a shoulder height of. The bull, averaging about is heavier than the cow, at an average of about. The largest individuals reportedly weigh up to.
The rich presence of blood vessels underneath the tissues in folds gives them the pinkish colour. The folds in the skin increase the surface area and help in regulating the body temperature. The thick skin does not protect against bloodsucking Tabanus flies, leeches and ticks.

Distribution and habitat

Indian rhinos once ranged across the entire northern part of the Indian subcontinent, along the Indus, Ganges and Brahmaputra River basins, from Pakistan to the Indian-Myanmar border, including Bangladesh and the southern parts of Nepal and Bhutan. They may have also occurred in Myanmar, southern China and Indochina. They inhabit the alluvial grasslands of the Terai and the Brahmaputra basin. As a result of habitat destruction and climatic changes its range has gradually been reduced so that by the 19th century, it only survived in the Terai grasslands of southern Nepal, northern Uttar Pradesh, northern Bihar, northern West Bengal, and in the Brahmaputra Valley of Assam. During the Late Pleistocene, its range extended into Thailand, Vietnam and Laos, and remains of rhinoceroses found in the Pleistocene of Southern China, otherwise assigned to the species "Rhinoceros sinensis", may actually represent the Indian rhinoceros.
The species was present in northern Bihar and Oudh at least until 1770 as indicated in maps produced by Colonel Gentil. On the former abundance of the species, Thomas C. Jerdon wrote in 1867:
Today, its range has further shrunk to a few pockets in southern Nepal, northern West Bengal, and the Brahmaputra Valley. Its habitat is surrounded by human-dominated landscapes, so that in many areas, it occurs in cultivated areas, pastures, and secondary forests. In the 1980s, Indian rhinos were frequently seen in the narrow plain area of Manas River and Royal Manas National Park in Bhutan.

Populations

In 2022, the total Indian rhinoceros population was estimated to be 4,014 individuals, up from 2,577 in 2006. Among them, 3,262 are in India and the remaining 752 are in Nepal and Bhutan. There is no permanent rhino population in Bhutan, but small rhino populations are occasionally known to cross from the Manas National Park or Buxa Tiger Reserve in India.
In India, there are around 2,885 individuals in Assam, including 2,613 in Kaziranga National Park, 125 in Orang National Park, 107 in Pobitora Wildlife Sanctuary and 40 in Manas National Park. West Bengal has a population of 339 individuals, including 287 in Jaldapara National Park and 52 in Gorumara National Park. Only 38 individuals are found in Dudhwa National Park, in Uttar Pradesh.
By 2014, the population in Assam increased to 2,544 Indian rhinos, an increase of 27% since 2006, although more than 150 individuals were killed by poachers during these years.
The population in Kaziranga National Park was estimated at 2,048 individuals in 2009. By 2009, the population in Pobitora Wildlife Sanctuary had increased to 84 individuals in an area of.
In 2015, Nepal had 645 Indian rhinos living in Parsa National Park, Chitwan National Park, Bardia National Park, Shuklaphanta Wildlife Reserve and respective buffer zones in the Terai Arc Landscape as recorded in a survey conducted from 11 April to 2 May 2015. The survey showed that the population of rhinos in Nepal from 2011 to 2015 increased 21% or 111 individuals.
The Indian rhino population, which once numbered as low as 100 individuals in the early 1900s, has increased to more than 3,700 in the year 2021 as per The International Rhino Foundation. According to a population census conducted in late March 2025, the estimated population is 4,075, with 3,323 in India and 752 in Nepal.