|Population||4,880 (2010 est.)|
|Conservation status||Critically endangered|
The black rhinoceros (Diceros bicornis) is a large mammal found in Africa south of the Sahara desert.
The black rhinoceros is a heavy-bodied animal, bearing a barrel-shaped body on stout, pillar-like legs with three-toed hooves. The skin is thick and grey-colored. It was assumed to have poor vision at one time, but recent research has disproved it, calling its sense of vision rather good, and enough to compliment its pronounced sense of smell and very good hearing.
The black rhinoceros stands 55-71 inches at the shoulder, is up to 12.4 feet in body length excluding the tail, and weighs between 1,760 to 3,090 pounds. Females are slightly smaller than males. The head is large, elongated, and bears two horns, of which the front horn can be longer (up to 55 inches) than its larger African relative, the white rhinoceros. Lacking a bony core, the horns are made entirely of keratin - the same material found in hair and fingernails - which continue to grow throughout life. The nasal bone supporting the horns is often massive and clearly arched forward, protruding over the intermediate jawbone. On the nasal bone there are distinct, "cauliflower" roughened structures on the bone surfaces where the horns begin. The brain case is relatively small for the size of the animal.
Eight subspecies are in existence today, but severely-reduced in numbers as a result of the illegal trade in rhino horns:
- Diceros bicornis bicornis, Southern black or Cape rhinoceros; nominate, and largest subspecies, once found throughout much of Transvaal to Namibia.
- Diceros bicornis brucii, North-eastern black rhinoceros; once found in the area of the Horn of Africa. Extinct early 20th century.
- Diceros bicornis chobiensis, Chobe black rhinoceros; southeastern Angola (Chobe valley), Namibia (Zambezi area), northern Botswana.
- Diceros bicornis ladoensis, Uganda black rhinoceros; South Sudan, Uganda, western Kenya, extreme southwestern Ethiopia.
- Diceros bicornis longipes, Western black rhinoceros; central/west Africa. Declared extinct in 2011.
- Diceros bicornis michaeli, Eastern black rhinoceros. Kenya and Tanzania
- Diceros bicornis minor, South-central black rhinoceros
- Diceros bicornis occidentalis, South-western black rhinoceros; western Namibia to southwestern Angola.
Of these subspecies, the nominate bicornis was once declared to be extinct about 1850; research has led some to believe this was an exaggeration based on the animal's extinction only in Namibia and the southern Cape area, with the paper's author excluding occidentalis as a recognized subspecies. The ICUN recognizes four as legitimate: bicornis, longpipes, michaeli, and minor.
Black rhinos are found throughout much of sub-Saharan grasslands, including the countries of Angola, Kenya, Mozambique, Namibia, South Africa, Tanzania, and Zimbabwe.
Social behavior and reproduction
The black rhinoceros is generally solitary, but can occur in small, matriarchal-organized herds. Bulls are mostly loners and live territorial. The individual animals live in tightly defined areas that are marked with urine and feces. They are more active during dusk and at night then they are during the daytime. They are shy animals that avoid human contact, so reports of rhino aggressiveness are usually greatly exaggerated. When threatened, the black rhinoceros will charge, using their horns as a primary weapon for defense of themselves or territory against other animal species.
After a gestation period of 15 to 18 months, a calf is born, and stays with the mother for two and a half to three years. If a second calf is born during this time the older one is chased away by the mother. The life expectancy is between 30 and a maximum of 50 years.
The black rhinoceros feeds exclusively on a vegetable diet, subsisting on soft plant foods such as leaves, branches, twigs, buds and fruits via browsing. The molars of these species usually have low dental crowns and less dental cement. In addition, it has a rather short, rectangular occipital bone due to the high head posture.
The single greatest threat to all species of rhinos is poaching by man, specifically a systematic killing of the animals for their horns, which are used in Chinese folk medicine in addition for use in ceremonial daggers in many Arab cultures. The black rhinoceros has suffered a decline of 96.7% since 1960 as a result, with the lowest recorded population of 2,410 in 1995. As of the end of 2010 the ICUN compiled the following status of the subspecies it recognizes:
- D. b. minor: 2,220 head.
- D. b. bicornis: 1,920 head.
- D. b. michaeli: 740 head.
Subspecies D. b. longipes was declared extinct in August, 2011 by the ICUN, the result of assessments made to its last known sighting in northern Cameroon in 2006; what was found instead was widespread evidence of poaching as well as official government monitors who admitted to faking the rhino's existence by laying false rhino tracks.