Africa has two extant species of rhinos – the White Rhino (Ceratotherium simum) and the Black Rhino (Diceros bicornis). These are giants among the continent’s herbivores, weighing up to 2,700 kg and 1,350 kg (on average) respectively. White Rhinos are grazers, living on the savanna. Black Rhinos are browsers, found in woodlands. This an example of two closely related and similar species evolving to occupy different niches.
Once upon a time, South Asia had a similar diversity. In fact, till recently, the region had more Rhino species than the continent of Africa. Only one has survived, the Indian Rhino (Rhinoceros unicornis). It is the second largest member of the family Rhinocerotidae after the White Rhino, reaching the same average weight. Confined to a few national parks in Nepal and India’s Northeast at present, this mega-herbivore once ranged over a belt of riverine grasslands and swamps covering the floodplains of the Indus and Ganges, from Pakistan in the West to Myanmar in the East.
The two species that disappeared were the Javan (Rhinoceros sondaicus) and Sumatran (Dicerorhinus sumatrensis) Rhinos. The former is a particularly close relative of the Indian Rhino, belonging to the same genus (Rhinoceros), having split off only a few million years ago. Like the Indian Rhino, it prefers lowland riverine tracts. Javan Rhinos were found in India’s East and Northeast, in Manipur, Assam, Bengal and Odisha. In many of these places, they were found alongside their much larger cousins.
The Sumatran Rhino, a more distant relative, with its distinct reddish coat, shaggy hair and stubby pair of horns, lived in both lowlands and uplands, in the cloud forests, swamps and jungles of India’s Northeast, and the adjoining areas of Bhutan and Bangladesh. It happened to be the smallest of the three, weighing in at 1,000 kg to the Javan’s 1,200 kg (on average). In fact, it is the smallest extant member of the family Rhinocerotidae. Both disappeared from South Asia in the 20th century due to poaching and habitat destruction.
Image Attribution: The image above, sourced from Wikimedia Commons, is the illustration of a Sumatran Rhino that appeared in the Proceedings of the Zoological Society of London in 1872.