Indian Rhinoceros: Physical Characteristics and Behavior
The Indian rhinoceros (Rhinoceros unicornis) is the largest of the three Asian rhinoceros. The Indian rhinoceros weighs between 1,800 and 2,700 kg (4,000 to 6,000 pounds). It is 2 meters (7 feet) tall at the shoulder and 3.5 meters (11.5 feet) long. The Indian rhinoceros is about the same size as the African white rhinoceros, but it differs from the Javan rhinoceros in that it is larger, has a huge horn, tubercles on its skin, and a different pattern of skin folds.
The Indian rhinoceros lives on the world’s tallest grasslands, where grasses can reach 7 meters (23 feet) tall by the end of the summer monsoon in October. They are mostly grazers, except in winter, when they ingest a higher proportion of forage. If an Indian rhinoceros female loses her calf, she will conceive soon.
Tigers kill 10-20% of calves, but they rarely kill calves over one-year-old, therefore Indian rhinoceroses that survive that age are immune to nonhuman predators. Instead of using its horn, the Indian rhinoceros fights with its razor-sharp lower outer incisor teeth. These teeth, or tusks, can grow to be 13 cm (5 inches) long in dominant males and inflict devastating wounds on other males contending for breeding females.
Historical and Current Range
The Indian rhinoceros used to roam much across northern India and Nepal, from Assam in the east to the Indus River basin in the west. Today, this species is confined to just about 11 reserves in India and Nepal. There are around 3,600 individuals of breeding age remaining in the wild. Because this species breeds in large numbers on nutrient-rich floodplains, rhinoceros populations recover swiftly when these habitats—and the rhinoceroses themselves—are protected from hunting.
Around 1900, there were only 12 Indian rhinoceroses in Kaziranga National Park in Assam State, but currently, the reserve is estimated to have around 2,400. Similarly, the Chitwan population fell to 60-80 animals in the late 1960s as a result of malaria eradication in the Chitwan Valley, conversion of natural habitat to rice cropping, and widespread poaching.
By 2000, the population had grown to more than 600 people, enough to allow some to be transferred to other reserves in Nepal and India where they had previously existed but had been eradicated. However, between 2000 and 2003, poachers murdered over 100 animals in Royal Chitwan National Park, reducing the reserve’s Indian rhinoceros population to less than 400. However, by 2015, the population had grown to more than 600 people as a result of successful anti-poaching operations.
Conservation Efforts and Population Recovery
In 2022, the total Indian rhinoceros population is expected to be 4,014 individuals, up from 2,577 in 2006. 3,262 of them are in India, with the remaining 752 in Nepal and Bhutan. Bhutan has no permanent rhino population, however, tiny rhino herds do from time to time pass from India’s Manas National Park or Buxa Tiger Reserve.
In India, Assam has over 2,885 people, with 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, with 287 in Jaldapara National Park and 52 in Gorumara National Park. Dudhwa National Park in Uttar Pradesh contains only 38 of them.
As of 2014, the Assam population had grown to 2,544 Indian rhinos, a 27% increase from 2006, even though poachers killed more than 150 individuals in this stretch. Kaziranga National Park’s population was estimated to be 2,048 in 2009. By 2009, the population of Pobitora Wildlife Sanctuary had grown to 84 in an area of 38.80 km2 (14.98 sq mi).
In a survey done between April 11 and May 2, 2015, Nepal had 645 Indian rhinos living in Parsa National Park, Chitwan National Park, Bardia National Park, Shuklaphanta Wildlife Reserve, and their specific buffer zones in the Terai Arc Landscape. According to the survey, Nepal’s rhino population expanded by 21%, or 111 animals, between 2011 and 2015. According to The International Rhino Foundation, the Indian rhino population has grown from as few as 100 in the early 1900s to more than 3,700 by 2021.
Ecological Role and Impact
The dung piles, or middens, of Indian rhinoceroses are interesting not only as areas for smell deposition and communication but also as sites for plant development. Indian rhinoceroses can deposit up to 25 kg (55 pounds) in a single feces, with more than 80% occurring on existing latrines rather than isolated clusters. Rhinoceroses help shade-intolerant plants populate open areas by defecating ingested fruit seeds from the forest floor. The dung piles of Indian rhinoceroses support remarkable collections of around 25 plant species, the seeds of which are consumed by rhinoceroses and germinate in the nutrient-rich excrement.