Black Rhinoceros
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? Black Rhinoceros Conservation status: Critical
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| Diceros bicornis Linnaeus, 1758 |
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The Black Rhinoceros (Diceros bicornis) is a mammal of the Perissodactyla order which lives in the eastern areas of Africa including Kenya, Tanzania, Cameroon, South Africa, Namibia and Zimbabwe. The black rhinoceros is on the endangered species list due to excessive poaching for their horns, which are mostly used in dagger handles as a symbol of wealth in many countries. Contrary to popular opinion, only small amounts of the horns are consumed as an aphrodisiac.
Characteristics
An adult black rhinoceros stands 5 feet (1.5 m) high at the shoulder and is anywhere from 10 to 12 feet (3 to 3.65 m) in length. An adult weighs from 1,000 to 3,000 lb (454 to 1362 kg), with the female being smaller. Two horns on the skull are made of keratin with the larger front horn as high as 28 inches (71 cm). Occasionally, a third smaller horn may develop. Skin colour depends more on local soil conditions and their wallowing behaviour than anything else, so many black rhinos are typically not truly black in colour.
The black rhinos are smaller than white rhinos and have a pointy prehensile upper lip, which they use to eat leafs and twigs. White rhinos have square lips used for grazing grass. The black rhino can also be recognized from the white rhino by its smaller skull and ears and its more pronounced forehead. Black rhinos also do not have a distinguishing shoulder hump like the white rhinos.
The adults are solitary in nature but come together for mating, with the females accompanying their young during the rearing period. Sometimes, mothers and daughters may form small groups.
Subspecies
There are four subspecies of the black rhinoceros:
- South-central (Diceros bicornis minor) which are the most numerous, and once ranged from central Tanzania south through Zambia, Zimbabwe and Mozambique to northern and eastern South Africa.
- South-western (Diceros bicornis bicornis) which are better adapted to the arid and semi-arid savannas of Namibia, southern Angola, western Botswana and western South Africa.
- East African (Diceros bicornis michaeli) which had a historic distribution from south Sudan, Ethiopia, Somalia down through Kenya into north-central Tanzania. Today, its range is limited primarily to Tanzania.
- West African (Diceros bicornis longipes) is the rarest and most endangered subspecies. Historically, it once occurred across most of the west African savanna. Nowadays, only a few individuals survive in northern Cameroon.
Adaptation
The black rhinoceros has adapted to its habitat using the following characteristics:
- A thick, layered skin protects the rhino from thorns and sharp grasses.
- The soles of their feet are thickly padded to cushion the legs and absorb shock.
- The upper lip has been adapted for seizing and grasping (prehensile) objects which helps in browsing and foraging.
- The large ears rotate to give directional information on sound
- The large nose has an excellent sense of smell to detect predators.
- Two formidable horns are used for defense and intimidation.
- An aggressive disposition discourages predators. The animal's nearsightedness seems to urge the rhino to charge first and investigate later.
Diet and mating
The black rhinoceros is a herbivorous browser that eats leafy plants, branches, shoots, thorny wood bushes and fruit. Their diet helps to reduce the amount of woody plants which results in more grasses growing for the benefit of other animals. Their skin harbors many external parasites, which are eaten by tickbirds and egrets that live with the rhino.
The females mature between four and six years of age while the males take a little longer, between seven and nine years. Mating does not have a seasonal pattern but live births tend to be towards the end of the rainy season in drier environments. A new born (calf) averages 85 pounds (38 kg) after a 15-16 month gestation period, and can follow its mother around after just three days. The young are a favorite target of hyenas and lions. Generally, females produce calves every two to three years. The lifespan for black rhinos is between 25 to 40 years but they can live up to 50 years in captivity.
Population
For most of the 20th century the black rhino was the most numerous of all rhino species. Around 1900 there were probably several hundred thousand [1] living in Africa. During the latter half of the 20th century their number severely reduced from an estimated 70,000 [2] in the late 1960s to only 10,000 to 15,000 in 1981. In the early 1990s the number dipped below 2500, and in 1995 it was reported that only 2,410 black rhinos remained. According to the International Rhino Foundation, the population has since then slightly recovered to 3,610 by 2003. Only a few [3] [4] scattered individuals of the West African subspecies remain in northern Cameroon.
