Rhinoceros

VI

Reproduction

Female rhinos reach sexual maturity at about the age of five or six, although the exact age varies from one species to another. The males mature slightly later, typically between the ages of seven and eight. They do not father calves until they have claimed a territory, which may take them three or four years. When a female is receptive, she may mate with several males, but males do not take any part in bringing up or protecting the young.

Rhino courtship can be a protracted business, because two essentially solitary animals have to overcome their wariness of each other. In white rhinos, the male serenades his prospective partner with a characteristic courtship call, but despite this, she often responds by charging. It takes repeated approaches before the male can overcome her hostility, and even then he may remain with her for nearly three weeks until she is finally prepared to mate. A few days after mating has taken place, the male departs, leaving the female on her own.

Rhinos always have a single calf, born after a gestation period of 15 to 18 months. The calf may feed on its mother’s milk for up to two years, and it usually remains with its mother until she is about to give birth once more. While the female is nursing, the bond formed with her calf is a strong one, and the two animals are rarely far apart.

A rhino’s early years are normally the only time when it is at risk to natural predators. Nursing mothers are quick to respond to any threat when they have a calf at their side. In Africa, black rhinos have been known to kill lions when defending their young, and in Asia, female Indian rhinos guarding their young are responsible for the deaths of several people each year.

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VII

Conservation Status

Until the late 1800s, rhinos were common animals throughout much of Africa and southern Asia. Since then, the twin pressures of habitat change and hunting have brought the rhino population close to collapse. By 2001, after three decades of particularly intense hunting for rhinoceros horn, less than 16,000 of these animals existed in the wild. With such small populations, rhinos run the risk of inbreeding (mating between close relatives). Inbreeding may cause future generations of rhinos to lack genetic variation, which makes them less able to adapt to changes in their environment, such as infectious disease or a climate change.

The Sumatran and Javan rhinos are listed as critically endangered on the Red List of Threatened Species prepared by the World Conservation Union (IUCN), a nongovernmental organization that compiles global information on endangered species. Both have been hunted for many years, but a rapid increase in logging that has destroyed their natural habitat has put further pressure on their survival. The Sumatran rhino population has declined by 50 percent in just 10 years, from about 600 animals in 1990 to about 300 animals today. A captive breeding program is underway to help the Sumatran rhino population rebound. No such programs are available for Javan rhinos and scientists hold little hope for the survival of the 60 or so remaining animals in the wild.

The situation of the black rhino is also very disturbing in terms of the sheer speed of its decline. In 1970 about 65,000 black rhinos were thought to live in the wild—about 25 times as many as today. Illegal poaching for rhinoceros horn has caused this headlong drop in numbers. In response, the IUCN has listed the black rhino as critically endangered and has launched a program to save the remaining wild populations, while working to stem the rhinoceros horn trade. National parks use armed guards to protect the animals in the wild. Some conservationists have advocated the drastic step of sawing off the horns of adults, so that the dehorned animals are no longer a target for hunters. Dehorning has been carried out on an experimental basis, but there are fears that it may reduce the rhinos’ ability to defend their young.

The outlook for the Indian and white rhinos is somewhat less dire. Both these animals have responded well to conservation management, and their numbers have increased gradually over recent years. However, both are now dependent on human intervention: Without round-the-clock protection from poaching, their future too would be in doubt.

Scientific classification: Rhinoceroses make up the family Rhinocerotidae. The Indian rhinoceros is classified as Rhinoceros unicornis, the Javan rhinoceros as Rhinoceros sondaicus, and the Sumatran rhinoceros as Dicerorhinus sumatrensis. The black rhinoceros is classified as Diceros bicornis, and the white rhinoceros as Ceratotherium simum.

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