Relics of another age, the tank-like rhinos are well-armored against any animal predators, but vulnerable to poaching for their horns. Although their eyesight is poor, rhinos have very well developed senses of smell and hearing. Rhinos are a declining group of mammals. In prehistoric times they were numerous and varied, but today they are heading towards extinction – unfortunately helped by mankind.
Rhinoceroses are large, tough-skinned herbivores immediately recognizable by the prominent horn (or horns, depending on the species) on their snouts. The name ‘rhinoceros’ comes from two Greek words ‘rhinos’ (nose) and ‘keras’ (horn). Unlike the horns of cattle, sheep or antelopes, those of the rhinos have no bony core; they consist of a densely packed outer layer of tough keratin fibres mounted on the skull. Although their eyesight is poor, rhinos have very well developed senses of smell and hearing.
Three species of rhino live in Asia. The Indian Rhino (Rhinoceros unicornis) or greater one-horned rhinoceros is the most westerly of the species. Once found along the length of the Ganges and Brahmaputra river, it is now largely confined to national parks such as the Chitwam in Nepal and the Kaziranga in Assam. Although some 1700 animals survive today – a vast improvement on the 40 or so animals that existed in 1910 – the Indians rhino still regarded as endangered.
The Indian rhino is a good swimmer. It lives a large solitary life, except when males and females meet briefly to breed or when a mother is rearing her young. Females occupy home ranges extending over nine to fifteen square kilometres; these areas overlap and are undefended, and the animal may wander even further afield in search of food and water. Males have large home ranges, which they will occasionally defend. Neighbours rarely fight or confront each other. Conflict may arise when a strange adult male enters another’s areas, but a dominant male will tolerate the presence of a weaker or non-breeding male in his home range.
The Javan Rhino (Rhinoceros sondaicus) or lesser one-horned rhinoceros (once found in Sumatra, Java, Indochina, China, and in Assam up as far as the Ganges Delta) is now severely reduced in numbers. Only about 50 survive in the Udjong Kulon Reserve near Jakarta, with possibly a few hanging on in remote parts of Indochina, making it one of the most endangered of all mammal species.
Scattered populations of the Sumatran or Asian two-horned rhinoceros inhabit Borneo, Burma, Thailand, Sumatra and Malaysia today; formerly it ranged from Assam and Bengal to Vietnam and south to Borneo. It is in several national parks such as such, Taman Negara in Malaysia and Kota Kinabalu in Borneo. Probably no more than 150 animals exist today.
The skins of Indians and Javan rhinos are hairless. The large Indians species may measure up to 1.9 m at the shoulder and weigh up to two and a quarter tonnes. The Javan rhinos are slightly smaller; it grows up to 1.7m high and weigh up to one and a half tonnes. The Sumatran rhino is still smaller, standing up 1.3 m and weighing up to 800 kg. It also distinguished by sparse covering of long hair.
The Sumatran rhinoceros (Dicerorhinus sumatrensis) is the smallest extant rhinoceros species, as well as the one with the most hair. It can be found at very high altitudes in Borneo and Sumatra. Due to habitat loss and poaching, its numbers have declined and it is the most threatened rhinoceros. About 275 Sumatran rhinos are believed to remain.
A mature rhino typically stands about 1.3 m (4 ft 3 in) high at the shoulder, has a length of 2.4–3.2 m (7 ft 10 in–10 ft 6 in) and weighs around 700 kg (1,500 lb), though the largest individuals have been known to weigh as much as 1,000 kilograms. Like the African species, it has two horns; the larger is the front (25–79 cm), with the smaller one usually less than 10 cm long. Males have much larger horns than the females. Hair can range from dense (the densest hair in young calves) to scarce. The color of these rhinos is reddish brown. The body is short and has stubby legs. The lip is prehensile.
The White Rhinos
There are two subspecies of white rhino: the southern white rhinoceros (Ceratotherium simum simum) and the northern white rhinoceros (Ceratotherium simum cottoni). The white rhino is the giant of the family, measuring up to two metres high at the giant of the shoulders and weighing two and a half to three and a half tonnes – a bulk exceeded in land mammals only by the elephants. As with the Indians rhino, mature white rhino males are much larger than the females. The black rhino is about the same size as the Javan Rhino – up to 1.6 m high and weighing up to 1.3 tonnes.
Since white and black rhinos are actually grey in colour, the best way to tell them apart is by comparing their shapes. White rhinos have a prominent hump on the back of their necks which contains the ligament needed to support their huge. They also have longer muzzle and broader mouth than the black rhino. Black rhinos have a lengthened upper lip which can grasp the branches of bushes and shrubs on which they feed.
The Black rhino (Diceros bicornis) is found throughout most of central and southern Africa. The greatest numbers are found in Tanzania and Kenya, mainly in the national parks, such as Serengeti, Ngorongoro, Masai- Mara, Amboseli and tsavo. It is relatively abundant and widespread. But it was once more numerous. In 1980 there were some 15,000 black rhinos; today, poaching throughout its range, especially south of the Zambezi River, has seriously depleted many black rhino populations and there are now under 9,000 animals. Recent reintroduction programmes in the parks of Zimbabwe and Mozambique, and the Addo Park of South Africa have improved the situation locally other populations live in the Etosha National Park in Namibia, in Somalia, Chad, Uganda and Zaire.
Although the black rhino is smaller than the white rhino, it has the reputation of being more aggressive, particularly towards humans. Marry African adventure stories feature a black rhino charging an intrepid hunter who bravely dispatches the ‘enraged beast’ with his gun. The myth of the black rhino’s aggression is based on a half- truth: whole an animal will always charge at an intruder (even another rhino) the charge is not an attack but a display. The animal will either veer off to one side, or stop the charge at a few feet from the victim.
Like other rhinos, black rhinos deposit dung as a means of marking pathways and territory. Where there are few rhinos per hectare, the home ranges of males overlap and are not usually defended by them. Where the density of black rhino is greater, such as in the Hluhluwe- Umfolozi Reserve in South Africa, breeding males will defend territories of 400 hectares against other breeding males. However, non- breeding males are still tolerated within these areas by the resident male. Mating takes place at any time of the year and is followed by a 15 month gestation. The single young, weighing 40kg at birth, lives with the mother for up to four years. Among black, white and Indian rhinos there is usually a space of two to four years before the females have another offspring. Births occur in any month.