Factfile: Greater one-horned rhino
- Common name: Greater one-horned rhino
- Synonym: Indian rhino
- Scientific name: Rhinoceros unicornis: "uni" meaning one and "cornis" meaning horn in Latin
- Size: the Greater one-horned rhino are second in size only to the white rhino.
- Weight: usually between 4-6,000 pounds (1,800-2,700 kg).
- Shoulder height: the Greater one-horned rhino stands at around 1.75-2 metres, and are 3-3.8 metres long.
- Skin colour: they have an ashy grey, hairless skin which develops thick folds, resembling armour plating. Several prominent folds of skin protect the neck. The skin has a maximum thickness of four cm; the subcutaneous fat is 2-5 cm thick and well supplied with blood, which helps thermo-regulation, so that the animal is able to regulate its own body temperature in varying weather conditions. Between the folds, around the stomach, the inner legs and the facial area, the skin is rather soft and thin.
- The horn: Greater one-horned rhinos have one horn, which is typically 20-61 cm long, and weighs up to three kg. It has the same horn structure as the hooves of horses and re-grows if broken off. It is not used for fighting but for the search of food and foraging for roots.
- Hair: found at the tip of the tail, around the ears and eyelashes.
- Distinctive characteristics: aside from their unique 'armour-plating' appearance, they have a prehensile upper lip, much like that of the black rhino, which assists in their foraging processes.
Location and Habitat
- Location: the Greater one-horned rhino can be found in India and Nepal, and particularly in the foothills of the Himalayas. In former times, greater one-horned rhinos roamed freely the floodplains and forests alongside the Brahmaputra, Ganges and Indus River valley.
- Habitat: Greater one-horned rhinos are closely adapted to the life along bodies of water, and often are seen to take up residence in swamps, forests and riverines, and anywhere that is near nutritious mineral licks.
Social behaviour and territory
- Sociability: Greater one-horned rhinos are usually solitary, except for females with small calves. Males have loosely defined territories where they live alone, and which they defend aggressively, but may overlap with other territories. The territories change according to food availability in relation to the current season. The females can move in and out of these territories as they like. If food is abundant within an area, it is not unusual to see several animals all grazing close together.
- Male territory: Male greater one-horned rhinos fight violently for preferred habitual areas. The death of one male in one of these fights is not uncommon (usually due to wounds a few days after the fight).
- Female territory: these tend to overlap with other territories, and again, depend on the resources available in a particular area.
- Scent- marking: 'middens' (rhino dung heaps) serve as communication points and mark territorial boundaries. Several animals often defecate at the same spot. Such a dung heap can become up to five metres wide and one metre high. After defecating, greater one-horned rhinos scratch their hind feet in the dung. By continuing to walk, they “transport” their own smell around the paths, thus establishing a scent-marked trail that is claimed by the rhino in question.
Breeding and Birth
- Sexual maturity: females may begin breeding at 4 years old, and males are usually sexually mature at 9 years old. There is no set breeding season for these animals, and a female will leave a gap of around 3-4 years between calves.
- Gestation period: this is between 15-16 months. Just as she is ready to give birth, the cow will find a solitary, quiet space to calve.
- Birth: At birth, a greater one-horned rhino calf can weigh as much as 58-70kg. The calf with remain with its mother for the first year and a half of its life, before being rejected.
- Maternal calves: A calf drinks on average 20-30 litres of milk per day and grows by 1-2 kg daily. They start nibbling / feeding on roughage at the age of 3-5 months and continue to suckle up to the age of 20 months in some cases. Young calves are also vulnerable to the predation of tigers in the wild.
Other interesting facts
- Food: They feed on wide variety of plants (up to 183 different species) with a strong seasonal variation: grass, fruits, leaves and branches of trees and shrubs, submerged and floating aquatic plants and agricultural crops. Greater one-horned rhinos eat on average 1% of their body weight daily, and are known to swim for their food also.
- Wallowing: mud wallows can be places where several individuals meet, as a kind of social gathering. Afterwards, they will separate again. By covering their skin in mud, this aids thermo-regulation by preventing overheating, and also suffocates any ticks or parasites that are embedded on the surface of the skin.
- Teeth: Although their horn may not be as long as other well-known species of rhino, Greater one-horned rhinos have very long lower incisor teeth that can be used in fighting to inflict deep wounds. In males they can grow up to 8 cm long.
- Sounds: In greater one-horned rhinos 12 different communication sounds are known which are frequently used, including snorts, honks and roars.
- Forest paths: Greater one-horned rhinos tend to use the same path, which are marked by a scent gland on the bottom of their feet. Traces of their urine and dung (as distribute on their feet also) act as scent-markers as well.
- Longevity: Greater one-horned rhinos live on average up to 30-45 years in the wild; while the longevity record for those in captivity is 40 years.
- Swimming: They are very good swimmers and can dive and feed under water, seemingly enjoying the cool, wet elements of the surrounding lakes and riverines of their habitats.
- Senses: They have a good sense of smell and hear very well, but are rather short sighted.
- Running speed: Greater one-horned rhinos can run fast (up to 40 km/h) and are very agile, despite their bulky shape and size.
- Poaching: The biggest threat that greater one-horned rhinos face is human harassment / encroachment. Since centuries ago, rhinos were hunted for sport and for their horn. The horn is used in Asia as a medicine against fever and pain. In the early 19th century, the greater one-horned rhino was almost hunted to extinction. The remaining animals were only found in protected reserves, where under the monitoring of certain organisations, populations are currently being brought back from the edge of extinction.
- Protection in the wild: With strict protection from Indian and Nepalese wildlife authorities, greater one-horned rhino numbers have recovered from under 200 last century to around 2,500 today. However, poaching has remained high and the success is precarious without continued and increased support for conservation efforts in India and Nepal.
- Other worrying threats: habitat destruction and loss are further threats to the rhinoceros population. As Greater one-horned rhinos live in areas with very fertile soil, humans use the same land for farming purposes. Conflicts between humans and animals are inevitable, and consequently damaging to the Greater one- horned rhino population.
Friederike von Houwald