Just the Facts: Rhinoceros also have acute hearing and sense of smell, but poor eyesight over any distance. Most rhinoceros live to be about 50 years old or more. A male rhinoceros is called a bull, a female a cow, and the young a calf; a group of rhinoceros is called a "crash".
Danger to man: Rhinoceros, despite being herbivorous, are dangerous animals. In India and Nepal, the Indian rhinos cause the greatest number of human deaths each year, surpassing those caused by tigers and leopards. They have been known to charge even working elephants carrying tourists through the jungles.
The five living species fall into three tribes.
Tribe one - Sumatran Rhinoceros: The critically endangered Sumatran Rhinoceros is the only surviving representative of the most primitive group, the Dicerorhinini, which emerged in the Miocene (abut 20 million years ago). The extinct Woolly Rhinoceros of northern Europe and Asia was also a member of this tribe.
Tribe two - Rhinocerotini: There are two living Rhinocerotini species, the endangered Indian Rhinoceros and the critically endangered Javan Rhinoceros, which diverged from one another about
10 million years ago.
Tribe three - African species: The two African species, the White Rhinoceros and the Black Rhinoceros, diverged during the early Pliocene
(about 5 million years ago) but the Dicerotini group to which they belong originated in the middle Miocene, about 14 million years ago. The main difference between black and white rhinos is the shape of their lips. White rhinos have broad flat lips for grazing and black rhinos have long pointed lips for eating foliage. The name White Rhinoceros was actually a mistake for wijd (wide) because of their square lips.
Horn Head: The most obvious distinguishing characteristic of the rhino is a large horn above the nose. The word rhinoceros comes from the Greek words rhino (nose) and keros (horn). Rhinoceros horns, unlike those of other horned mammals, consist of keratin only and lacks a bony core,such as bovine horns.
Rhinos in Danger: Rhinoceros horns are used in traditional Asian medicine, and for dagger handles in Yemen and Oman. None of the five rhinoceros species have secure futures; the White Rhinoceros is perhaps the least endangered, the Javan Rhinoceros survives in only tiny numbers (estimated at 60 animals in 2002) and is one of the two or three most endangered large mammals anywhere in the world.
Protection: Rhino protection campaigns began in the 1970s, but rhino populations have continued to decline dramatically. Trade in rhinoceros parts is forbidden under the CITES agreements, but poaching is a severe threat to all rhinoceros species.
Black Rhino: The adults are solitary in nature, coming together only for mating. Mating does not have a seasonal pattern but births tend to be towards the end of the rainy season in drier environments.
The gestation period is 15–16 months; the single calf weighs about 35–50 kg at birth, and can follow its mother around after just three days. The mother and calf stay together for 2–3 years until the next calf is born; female calves may stay longer, forming small groups.
The young are occasionally taken by hyenas and lions. Sexual maturity is reached from 5 years old for females, from 7 years for males, and the life expectancy in natural conditions (without poaching pressure) is from 35–50 years.
Indian Rhino: Males can breed at nine years of age and females reach sexual maturity at five years and have their first calves when between six and eight years. The female whistles when in season so that males know when she is ready to mate. The gestation period is about 16 months. A single calf is born at intervals of about three years. Mother rhinos are attentive and protective, the young staying with the mother for several years. Females and their young travel together, but males usually travel alone and are territorial. Indian rhinos live up to an age of 45 years.
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