The Black Rhinoceros has a large, bulky body that is grey to grey-brown in color and nearly hairless. The two horns on its nose are longer and thinner in females than males. A pointed, prehensile upper lip distinguishes this species from its square-lipped cousin, the White Rhinoceros.
There are now three remaining recognized ecotypes/subspecies of Black Rhinoceros occupying different areas of Africa. A fourth recognised subspecies D. b. longipes once ranged through the savanna zones of central-west Africa but it is now considered to have gone extinct in its last known habitats in Northern Cameroon.
The other three more numerous subspecies are found in the eastern and southern African countries. Today putative D. b. bicornis range includes Namibia, southern Angola, western Botswana, and south-western and south-eastern South Africa (up to the Kei River), although today they occur only in Namibia (the stronghold) and South Africa with a sighting of one animal in Angola and unconfirmed reports of possibly another three animals.
D. b. michaeli was distributed from southern Sudan, Ethiopia, and Somalia, through Kenya into northern-central Tanzania and Rwanda. Its current stronghold is Kenya. Smaller but growing numbers occur in northern Tanzania. The single animal that survived in Rwanda has died. One important free-ranging population occurs outside its range in a private game reserve in South Africa. Contractually, these D. b. michaeli animals may only be translocated back to historical range and not elsewhere in South Africa. The repatriation of some of these animals back to former subspecies range in Tanzania commenced in 1997, with animals going to Mkomazi Game Reserve and Ngorongoro Crater Conservation Area and the most recent being five animals moved to the Serengeti National Park, Tanzania in 2010.
D. b. minor is believed to have occurred from southern Tanzania through Zambia, Zimbabwe, and Mozambique to the northern, north-western and north-eastern parts of South Africa (north of the Mtamvuna river). It also probably occurred in southern Democratic Republic of the Congo, northern Angola, eastern Botswana, Malawi, and Swaziland. Today, its stronghold is South Africa and to a lesser extent Zimbabwe, with smaller numbers remaining in southern Tanzania. The South-central Black Rhino is now thought to be extinct in Angola and only one individual has been sighted in Mozambique since the 2008 IUCN African Rhino Specialist Group (AfRSG) meeting. The subspecies has also been reintroduced to Botswana, Malawi, Swaziland and Zambia.
Note: At the request of certain members, the AfRSG has a policy of not releasing detailed information on the whereabouts of all rhino populations for security reasons. For this reason, only whole countries are shaded on the map.
Historically, Diceros bicornis has been distributed throughout Africa, south of the Sahara, with the exception of the Congo Basin. The current range of black rhinoceroses is bounded by Cameroon, Kenya, and South Africa but their distribution within those limits is fragmented.
Biogeographic Regions: ethiopian (Native )
- Brooks, M. 2002. "Black Rhinoceros (Diceros bicornis)" (On-line). Arkive. Accessed April 09, 2009 at http://www.arkive.org/black-rhinoceros/diceros-bicornis/info.html.
- Grzimek, B. 2005. "Black Rhinoceros" (On-line). Answers.com. Accessed April 09, 2009 at http://www.answers.com/topic/black-rhinoceros-1.
- World Wildlife Fund, 2004. "WWF Factsheet: Black Rhinoceros - Diceros bicornis" (On-line pdf). Accessed April 09, 2009 at http://assets.panda.org/downloads/ecop13blackrhinofactsheet.pdf.
Although the color of black rhinoceroses can vary from yellow-brown to dark-brown, the general color is grey. Specific skin color depends on the soil conditions within the habitat of each individual. The skin is naked or hairless, with the exception of short, fringe-like hair on the short and rounded ears. On average, black rhinos have a shoulder height between 1.4 and 1.8 m, a head and body length between 3 and 3.75 m, and a weight between 800 and 1400 kg. Tail length is generally around 0.7 m. Although similar in size, males are normally a little larger than females.
Black rhinos have two horns, one posterior and one anterior, which are made from keratin instead of bone. The anterior horn is normally longer, measuring 42 to 128 cm, while the posterior horn is 20 to 50 cm. In some cases, black rhinos have a third, posterior horn, which is small. Females tend to have longer and thinner horns than males.
The trait that distinguishes black rhinos from white rhinos is the pointed, prehensile upper lip found in black rhinos, as opposed to the square lips found in white rhinos. This lip is used to pick up food such as twigs. Additionally, black rhinos have smaller heads, shorter ears, and shorter horns than white rhinos.
Range mass: 800 to 1400 kg.
Range length: 3.0 to 3.75 m.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike; male larger; sexes shaped differently; ornamentation
- Lang, E. 1983. "Diceros bicornis" (On-line pdf). CITES. Accessed April 09, 2009 at http://www.cites.org/eng/resources/ID/fauna/Volume1/A-118.003.003.001%20Diceros%20bicornis_E.pdf.
Habitat and Ecology
Black rhinoceroses live in various habitats that range from deserts to grasslands, both tropical and subtropical. They are also present in African forests, especially in areas where grasslands and forests phase into one another. Black rhinos generally stay within 25 kilometers of water.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: desert or dune ; savanna or grassland ; scrub forest
- Massicot, P. 2006. "Black Rhinoceros" (On-line). Animal Info. Accessed April 09, 2009 at http://www.animalinfo.org/species/artiperi/dicebico.htm#Weight.
Historically, the Black Rhinoceros was found in savannas, woodlands, forests, and arid lands throughout sub-Saharan Africa. Today, the range of the Black Rhinoceros is bounded by Cameroon, Kenya, and South Africa but their distribution within those limits is fragmented.
Black rhinos are browsers that feed on items such as twigs, woody shrubs, small trees, legumes, and grass. Black rhinos show a preference for Acacia species, as well as plants in the family Euphorbiaceae. They eat an average of 23.6 kg during the course of each day. Black rhinos use their characteristic prehensile upper lip to grab plants and guide them into their mouths, where their cheek teeth can do the rest of the work. In addition, black rhinos use their horns to gain access to higher branches by breaking or knocking down plants. Scraping bark off of trees is also part of the repertoire of black rhino feeding.
Plant Foods: leaves; wood, bark, or stems; seeds, grains, and nuts
Primary Diet: herbivore (Folivore , Lignivore)
Black rhinos and oxpeckers (Buphagus species) are involved in a mutualistic relationship where the oxpeckers eat parasites taken from the rhino’s skin. Additionally, oxpeckers are able to warn rhinos of approaching predators because their vision is much better than the rhino’s vision. Black rhinos are significant herbivores and influence plant communities.
Ecosystem Impact: disperses seeds
Humans, Homo sapiens, are the most important predator of black rhinos; however, both lions (Panthera leo) and spotted hyaenas (Crocuta crocuta) sometimes prey on young rhinos. Lions also sometimes attack adults. Black rhinos use their size and strength as a defense mechanism by charging at their predators both to threaten predators and actively defend themselves and their offspring.
- Berger, J. 1994. Science, Conservation, and Black Rhinos. Journal of Mammalogy, 75(2): 298-308.
Life History and Behavior
Communication and Perception
Although black rhinos use vision, acoustic, and smell senses, their sense of smell is what they rely on most. They have poor vision, with the ability to see only 25 to 30 m away. Their sense of hearing is good, but not up to the level of their sense of smell. Black rhinos use the pheromones and scents from their feces and urine to mark territories. Additionally, they engage in calls to one another that can take the form of the pant-squeal interaction seen in mothers and their infants to loud roars that signify aggression. When a subordinate male enters the territory of a more dominant male, the combination of calls and territorial scents causes the subordinate male to retreat.
Communication Channels: visual ; tactile ; acoustic ; chemical
Other Communication Modes: pheromones ; scent marks
Perception Channels: visual ; acoustic
The Black Rhinoceros is a browser that feeds on twigs, woody shrubs, small trees, legumes, and grasses. This species uses its characteristic prehensile upper lip to grab plants and guide them into its mouth. BlackRhinoceroses forage during dawn and dusk and rest during the heat of the day.
The Black Rhinoceros is generally a solitary creature, but during the breeding season male rhinoceroses court females by following them for one to two weeks before mating. Females give birth and rear single calves every two to four years. Calves remain with their mothers until the birth of her next offspring.
Typical lifespan in the wild is between 30 and 35 years, with little expectation of exceeding 35 years. In captivity, black rhinos can live over 45 years, with the record being 49 years. Factors that limit lifespan in the wild include poaching for horns and habitat fragmentation.
Status: wild: 35 years.
Status: captivity: 49 years.
Status: wild: 30 to 35 years.
Status: captivity: 30 to 45 years.
Lifespan, longevity, and ageing
Adult black rhinos are typically solitary creatures. However, during mating, black rhino adults come together. Black rhinos are polygynous. Male rhinos begin a courtship by following females, including their dependent offspring, for approximately one or two weeks before mating actually begins; even while sleeping, the male and female remain in contact with one another. Males exhibit certain behavioral characteristics before mating: they walk in a stiff-legged manner and brush their horns along the ground in front of the female. Before copulation begins, many attempts by the male to mount the female are made; if the female is not yet ready, she will make a series of attacks or charges at the male. When insertion is actually achieved, copulation lasts between 20 and 40 minutes. If the mating is unsuccessful, females return to a state of heat within 35 days of the previous copulation.
Mating System: polygynous
Breeding occurs throughout the year but peak breeding season varies by location. Gestation lasts approximately 15 months. Females give birth to one offspring at a time, which usually weighs between 20 and 25 kg. Weaning of offspring typically occurs after 18 months, but offspring remain dependent for up to 4 years. Females achieve sexual maturity at age 5 to 7 years; males reach maturity between 7 and 8 years.
Breeding interval: Black rhinos breed every 2 to 2.5 years under the most favorable conditions, but interbreeding periods can last up to 4 years.
Breeding season: Black rhinos mate throughout the year, with peak breeding seasons depending on the location of the population.
Average number of offspring: 1.
Average gestation period: 15 months.
Range birth mass: 20 to 25 kg.
Average weaning age: 18 months.
Range time to independence: 2 to 4 years.
Range age at sexual or reproductive maturity (female): 5 to 7 years.
Range age at sexual or reproductive maturity (male): 7 to 8 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous
Average gestation period: 474 days.
Average number of offspring: 1.
For the first week after birth the offspring is hidden by the mother. After that, the mother and calf use specific vocalizations to find one another: the mother pants and the calf squeals. Black rhino mothers are very protective of their calves, which is why calves walk behind their mothers. This differs from white rhino females, who have their young walk in front of them. Calves are able to browse on their own after one month and able to drink water after 4 to 5 months. Black rhino offspring aren’t weaned until 18 months; after that, the calf remains dependent on its mother for up to 4 years. The basic social unit for females is typically a female and her young offspring, until the offspring is forced into independence by a sibling.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Protecting: Female)
- Garnier, J., M. Bruford, B. Goossens. 2001. Mating system and reproductive skew in the black rhinoceros. Molecular Ecology, 10: 2031-2041.
- Garnier, J., W. Holt, P. Watson. 2002. Non-invasive assessment of oestrous cycles and evaluation of reproductive seasonality in the female wild black rhinoceros (Diceros bicornis minor). Reproduction, 123: 877-889.
- Hillman-Smith, A., C. Groves. 1994. Diceros bicornis. Mammalian Species, 455: 1-8.
- Brooks, M. 2002. "Black Rhinoceros (Diceros bicornis)" (On-line). Arkive. Accessed April 09, 2009 at http://www.arkive.org/black-rhinoceros/diceros-bicornis/info.html.
- Dollinger, P., S. Geser. 2008. "Black Rhinoceros" (On-line). World Association of Zoos and Aquariums - Virtual Zoo. Accessed April 09, 2009 at http://www.waza.org/virtualzoo/factsheet.php?id=118-003-003-001&view=Rhinos&main=virtualzoo.
- Grzimek, B. 2005. "Black Rhinoceros" (On-line). Answers.com. Accessed April 09, 2009 at http://www.answers.com/topic/black-rhinoceros-1.
- Massicot, P. 2006. "Black Rhinoceros" (On-line). Animal Info. Accessed April 09, 2009 at http://www.animalinfo.org/species/artiperi/dicebico.htm#Weight.
Molecular Biology and Genetics
Barcode data: Diceros bicornis
There are 2 barcode sequences available from BOLD and GenBank. Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Diceros bicornis
Public Records: 2
Specimens with Barcodes: 5
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
Listed as Critically Endangered as the population of Black Rhino has declined by an estimated 97.6% since 1960 with numbers bottoming out at 2,410 in 1995, mainly as a result of poaching. Since then, numbers have been steadily increasing at a continental level with numbers doubling to 4,880 by the end of 2010. Current numbers are however still 90% lower than three generations ago.
- 2011Critically Endangered
- 2003Critically Endangered
- 2003Critically Endangered(IUCN 2003)
- 2002Critically Endangered
- 1996Critically Endangered
- 1994Endangered(Groombridge 1994)
- 1990Endangered(IUCN 1990)
- 1988Endangered(IUCN Conservation Monitoring Centre 1988)
- 1986Endangered(IUCN Conservation Monitoring Centre 1986)
Date Listed: 07/14/1980
Lead Region: Foreign (Region 10)
Where Listed: Sub-Saharan Africa
Population location: Sub-Saharan Africa
Listing status: E
For most current information and documents related to the conservation status and management of Diceros bicornis , see its USFWS Species Profile
Black rhinos have been on Appendix I of CITES since 1977. Additionally, black rhinos have been listed since 1980 under the United States Endangered Species Act. Black rhinos are listed as critically endangered by the IUCN Red List. Currently, there are four subspecies of black rhinos: D. bicornis bicornis, D. bicornis longipes, D. bicornis minor, and D. bicornis michaeli. The first subspecies is listed as vulnerable on the IUCN 2008 Red List, and the latter three are all listed as critically endangered. Conservation efforts to preserve black rhinos include establishing a ban against the horn trade, creating fenced sanctuaries for black rhinos to better protect them from poachers, and dehorning black rhinos to decrease incentive for poaching. With these efforts, the total population of 2,400 black rhinos towards the end of the twentieth century increased to 3,100 black rhinos by 2001.
US Federal List: endangered
CITES: appendix i
State of Michigan List: no special status
IUCN Red List of Threatened Species: critically endangered
- Convention on International Trade in Endangered Species of Wild Fauna and Flora, 2009. "CITES-listed Species Database" (On-line). Accessed April 09, 2009 at http://www.cites.org/eng/resources/species.html.
- IUCN Species Survival Commission, 2008. "IUCN 2008 Red List" (On-line). Accessed April 09, 2009 at http://www.iucnredlist.org.
- U.S. Fish and Wildlife Service, 2009. "Endangered Species Program" (On-line). Accessed April 09, 2009 at http://www.fws.gov/endangered/.
IUCN Red List Status: CRITICALLY ENDANGERED
Recent conservation efforts include a ban on rhino horn trade, creating protective sanctuaries, and dehorning rhinos to remove the incentive for poaching.
Throughout most of the 20th century, the Black Rhino was the most numerous of the world's rhino species which at one stage could have numbered around 850,000. Relentless hunting of the species and clearances of land for settlement and agriculture reduced numbers and by 1960 only an estimated 100,000 remained. Between 1960 and 1995, large-scale poaching caused a dramatic 98% collapse in numbers. Over this period numbers only increased in South Africa and Namibia from an estimated 630 + 300 in 1980 (Emslie and Brooks 1999) to 1,915 + 1,750, respectively by the end of 2010 (AfRSG data 2011). Continentally numbers bottomed out at only 2,410 in 1995 (Emslie and Brooks 1999). From 1992â1995 total numbers remained relatively stable with increases in some countries (those with the best-protected and managed populations) being cancelled out by declines in others. However, since the low of 1995, Black Rhino numbers at a continental level have increased every time continental population estimates have been revised by the AfRSG reaching 4,880 by December 2010 (Emslie 2006; Emslie et al. 2007; AfRSG data 2008, 2011).
Subspecies totals as of 31 December 2010 are (see also Table 1 in the attached pdf): Southern-central Black Rhino (D. b. minor) 2,220, South-western Black Rhino (D. b. bicornis) 1,920 and Eastern Black Rhino (D. b. michaeli) 740 based on 2011 AfRSG data. In Cameroon, no evidence of the Western Black Rhino was found during extensive surveys over much of its known range during the dry season in 2006 and since then there have been no reports of either rhino sightings or spoor and this subspecies is considered extinct.
Increases in numbers have occurred in countries where investments in conservation programmes, including monitoring and law enforcement, have been high. As with White Rhinos, four range states (South Africa, Namibia, Zimbabwe and Kenya) currently conserve the majority (96.1%) of remaining wild Black Rhino.
As of December 2005, an additional 240 Black Rhino (171 D. b. michaeli and 69 D. b. minor) occurred in captivity worldwide (Emslie et al. 2007).
The Black Rhino faces a variety of threats. The main threat is poaching for the international rhino horn trade. Rhino horn has two main uses: traditional (and more recently new non-traditional) use in Chinese medicine, and ornamental use (for example, rhino horn is a highly prized material for making ornately carved handles for ceremonial daggers or Jambiyas worn in some Middle East countries). In recent years there has been an upsurge in black market prices for rhino horn which has coincided with an increase in poaching in some range states. This increase has coincided with new use of rhino horn to supposedly treat cancer (a non-traditional use) and one for which there is no supporting clinical evidence of its effectiveness. In areas where both African species co-exists, the White Rhino acts as buffer against Black Rhino poaching as White Rhinos are more likely to be poached given they are easier to find given their preference for more open habitats and the fact they cluster in small groups.
Civil unrest, the free flow of weapons and better communication systems in Africa have had a significant impact on African rhino conservation efforts. Black Rhino populations in Angola, Cameroon, Central African Republic, Chad, Democratic Republic of the Congo, Mozambique, Namibia, Rwanda, Somalia, Sudan and Uganda have to varying degrees all suffered from the consequences of war and civil unrest since the 1960s (Emslie and Brooks 1999). The negative effects of this have been exacerbated when combined with lack of political will and lack of conservation expenditure by some governments. Some detrimental effects include trading of rhino horn and ivory for weapons, increased poaching due to increased poverty in times of civil unrest, and diminished levels of protection for rhino populations as funds are diverted away from wildlife departments. Other threats that can cause populations to decline include habitat changes, competing species and alien plant invasions.
Black Rhinoceros were nearly poached to extinction due to the demand for their horn, used in Chinese medicine and for Yemeni dagger handles.
Relevance to Humans and Ecosystems
Economic Importance for Humans: Negative
Although many charges by black rhinos towards humans and their vehicles turn into innocent advances, some may cause injury or death to humans, or damage to vehicles that results in monetary loss.
Negative Impacts: injures humans
Economic Importance for Humans: Positive
Black rhinos have the potential to help create awareness for conservation efforts. Additionally,they provide educational value both through biology and through art. Black rhino horns are also very valuable for their use in various products, such as traditional Chinese medicine and traditional Yemen dagger handles. The popularity of their horns is a major reason why the species as a whole is in trouble.
Positive Impacts: body parts are source of valuable material; source of medicine or drug ; research and education
The black rhinoceros or hook-lipped rhinoceros (Diceros bicornis) is a species of rhinoceros, native to eastern and central Africa including Kenya, Tanzania, Cameroon, South Africa, Namibia, Zimbabwe, and Angola. Although the rhinoceros is referred to as black, its colors vary from brown to grey.
The other African rhinoceros is the white rhinoceros (Ceratotherium simum). The word "white" in the name "white rhinoceros" is a misinterpretation of the Afrikaans word wyd, itself derived from the Dutch word wijd for wide, referring to its square upper lip, as opposed to the pointed or hooked lip of the black rhinoceros. These species are now sometimes referred to as the square-lipped (for white) or hook-lipped (for black) rhinoceros.
The species was first named Rhinoceros bicornis by Carolus Linnaeus in the 10th edition of his Systema naturae in 1758. The name means "double-horned rhinoceros". There is some confusion about what exactly Linnaeus conceived under this name as this species was probably based upon the skull of a single-horned Indian rhinoceros (Rhinoceros unicornis), with a second horn artificially added by the collector. Such a skull is known to have existed and Linnaeus even mentioned India as origin of this species. However he also referred to reports from early travellers about a double-horned rhino in Africa and when it emerged that there is only one, single-horned species of rhino in India, "Rhinoceros" bicornis was used to refer to the African rhinos (the white rhino only became recognised in 1812). In 1911 this was formally fixed and the Cape of Good Hope officially declared the type locality of the species.
The intraspecific variation in the black rhinoceros has been discussed by various authors and is not finally settled. The most accepted scheme considers seven or eight subspecies, of which three became extinct in historical times and one is on the brink of extinction:
- Southern black rhinoceros or Cape rhinoceros (D. b. bicornis) – Extinct. Once abundant from the Cape of Good Hope to Transvaal, South Africa and probably into the south of Namibia, this was the largest subspecies. It became extinct due to excessive hunting and habitat destruction around 1850.
- North-eastern black rhinoceros (D. b. brucii) – Extinct. Formerly central Sudan, Eritrea, northern and southeastern Ethiopia, Djibouti and northern and southeastern Somalia. Relict populations in northern Somalia vanished during the early 20th century.
- Chobe black rhinoceros (D. b. chobiensis) – A local subspecies restricted to the Chobe Valley in southeastern Angola, Namibia (Zambezi Region) and northern Botswana. Nearly extinct, possibly only one surviving specimen in Botswana.
- Uganda black rhinoceros (D. b. ladoensis) – Former distribution from South Sudan, across Uganda into western Kenya and southwesternmost Ethiopia. Black rhinos are considered extinct across most of this area and its conservational status is unclear. Probably surviving in Kenyan reserves.
- Western black rhinoceros (D. b. longipes) – Extinct. Once lived in South Sudan, northern Central African Republic, southern Chad, northern Cameroon, northeastern Nigeria and south-eastern Niger. The range possibly stretched west to the Niger River in western Niger, though this is unconfirmed. The evidence from Liberia and Burkina Faso mainly rests upon the existence of indigenous names for the rhinoceros. A far greater former range in West Africa as proposed earlier is doubted by a 2004 study. The last known wild specimens lived in northern Cameroon. In 2006 an intensive survey across its putative range in Cameroon failed to locate any, leading to fears that it was extinct in the wild. On November 10, 2011 the IUCN declared the western black rhinoceros extinct.
- Eastern black rhinoceros (D. b. michaeli) – Had a historical distribution from South Sudan, Ethiopia, down through Kenya into north-central Tanzania. Today, its range is limited primarily to Tanzania.
- South-central black rhinoceros (D. b. minor) – Most widely distributed subspecies, characterised by a compact body, proportionally large head and prominent skin-folds. Ranged from north-eastern South Africa (KwaZulu-Natal) to northeastern Tanzania and southeastern Kenya. Preserved in reserves throughout most of its former range but probably extinct in eastern Angola, southern Democratic Republic of Congo and possibly Moçambique. Extinct but reintroduced in Malawi, Botswana, and Zambia.
- South-western black rhinoceros (D. b. occidentalis) – A small subspecies, adapted to survival in desert and semi-desert conditions. Originally distributed in north-western Namibia and southwestern Angola, today restricted to wildlife reserves in Namibia with sporadic sightings in Angola. These populations are often erroneously referred to D. b. bicornis or D. b. minor but represent a subspecies in their own right.
The most widely adopted alternative scheme only recognizes five subspecies or "eco-types", D. b. bicornis, D. b. brucii, D. b. longipes, D. b. michaeli, and D. b. minor. This concept is also used by the IUCN, listing three surviving subspecies and recognizing D. b. brucii and D. b. longipes as extinct. The most important difference to the above scheme is the inclusion of the extant southwestern subspecies from Namibia in D. b. bicornis instead of in its own subspecies, whereupon the nominal subspecies is not considered extinct.
The rhinoceros originated in the Eocene about fifty million years ago alongside other ungulates (hooved animals). Ancestors of the black and the white rhinoceros were present in Africa by the end of the Late Miocene about ten million years ago. The two species evolved from the common ancestral species Ceratotherium neumayri during this time. The clade comprising the genus Diceros is characterised by an increased adaptation to browsing. Between four and five million years ago, the black rhinoceros diverged from the white rhinoceros. After this split, the direct ancestor of Diceros bicornis, Diceros praecox was present in the Pliocene of East Africa (Ethiopia, Kenya, Tanzania). D. bicornis evolved from this species during the Late Pliocene – Early Pleistocene.
An adult black rhinoceros stands 132–180 cm (52–71 in) high at the shoulder and is 2.8–3.8 m (9.2–12.5 ft) in length, plus a tail of about 60 cm (24 in) in length. An adult typically weighs from 800 to 1,400 kg (1,800 to 3,100 lb), however unusually large male specimens have been reported at up to 2,199–2,896 kg (4,848–6,385 lb). The females are smaller than the males. Two horns on the skull are made of keratin with the larger front horn typically 50 cm (20 in) long, exceptionally up to 140 cm (55 in).
The longest known black rhinoceros horn measured nearly 1.5 m (4.9 ft) in length. Sometimes, a third, smaller horn may develop. These horns are used for defense, intimidation, and digging up roots and breaking branches during feeding. The black rhino is smaller than the white rhino, and is close in size to the Javan Rhino of Indonesia. It and has a pointed and prehensile upper lip, which it uses to grasp leaves and twigs when feeding. The white rhinoceros has square lips used for eating grass. The black rhinoceros can also be distinguished from the white rhinoceros by its size, smaller skull, and ears; and by the position of the head, which is held higher than the white rhinoceros, since the black rhinoceros is a browser and not a grazer. This key differentiation is further illustrated by the shape of the two species mouths (lips): the "square" lip of the white rhinoceros is an adaptation for grazing, and the "hooked" lip of the black rhinoceros is an adaptation to help browsing.
Their thick-layered skin helps to protect the rhino from thorns and sharp grasses. Their skin harbors external parasites, such as mites and ticks, which may be eaten by oxpeckers and egrets. Such behaviour was originally thought to be an example of mutualism, but recent evidence suggests that oxpeckers may be parasites instead, feeding on rhino blood. Black rhinos have poor eyesight, relying more on hearing and smell. Their ears have a relatively wide rotational range to detect sounds. An excellent sense of smell alerts rhinos to the presence of predators.
As with many other components of the African large mammal fauna, black rhinos probably had a wider range in the northern part of the continent in prehistoric times than today. However this seems to have not been as extensive as that of the white rhino. Unquestionable fossil remains have not yet been found in this area and the abundant petroglyphs found across the Sahara desert are often too schematic to unambiguously decide whether they depict black or white rhinos. Petroglyphs from the Eastern Desert of southeastern Egypt relatively convincingly show the occurrence of black rhinos in these areas in prehistoric times.
Historical and extant range
The natural range of the black rhino included most of southern and eastern Africa, but it did not occur in the Congo Basin, the tropical rainforest areas along the Bight of Benin, the Ethiopian Highlands, and the Horn of Africa. Its former native occurrence in the extremely dry parts of the Kalahari desert of southwestern Botswana and northwestern South Africa is uncertain. In western Africa it was abundant in an area stretching east to west from Eritrea and Sudan through South Sudan to southeastern Niger, and especially around Lake Chad. Its occurrence further to the west is questionable, though often purported to in literature. Today it is totally restricted to protected nature reserves and has vanished from many countries in which it once thrived, especially in the west and north of its former range. The remaining populations are highly scattered. Some specimens have been relocated from their habitat to better protected locations, sometimes across national frontiers. The black rhino has been successfully reintroduced to Malawi since 1993, where it became extinct in 1990. Similarly it was reintroduced to Zambia (North Luangwa National Park) in 2008, where it had become extinct in 1998, and to Botswana (extinct in 1992, reintroduced in 2003).
|This section needs additional citations for verification. (November 2011)|
Black rhinoceros are generally thought to be solitary, with the only strong bond between a mother and her calf. In addition, males and females have a consort relationship during mating, also subadults and young adults frequently form loose associations with older individuals of either sex. They are not very territorial and often intersect other rhino territories. Home ranges vary depending on season and the availability of food and water. Generally they have smaller home ranges and larger density in habitats that have plenty of food and water available, and vice versa if resources are not readily available. Sex and age of an individual black rhino influence home range and size, with ranges of females larger than those of males, especially when accompanied by a calf. In the Serengeti home ranges are around 70 to 100 km2 (27 to 39 sq mi), while in the Ngorongoro it is between 2.6 to 58.0 km2 (1.0 to 22.4 sq mi). Black rhinos have also been observed to have a certain area they tend to visit and rest frequently called "houses" which are usually on a high ground level. These "home" ranges can vary from 2.6 km2 to 133 km2 with smaller home ranges having more abundant resources than larger home ranges.
Black rhinoceros in captivity and reservations sleep patterns have been recently studied to show that males sleep longer on average than females by nearly double the time. Other factors that play a role in their sleeping patterns is the location of where they decide to sleep. Although they do not sleep any longer in captivity, they do sleep at different times due to their location in captivity, or section of the park.
The black rhino has a reputation for being extremely aggressive, and charges readily at perceived threats. They have even been observed to charge tree trunks and termite mounds. Black rhinos will fight each other, and they have the highest rates of mortal combat recorded for any mammal: about 50% of males and 30% of females die from combat-related injuries. Adult rhinos normally have no natural predators, thanks to their imposing size as well as their thick skin and deadly horns. However, adult black rhinos have fallen prey to crocodiles in exceptional circumstances. Calves and, very seldom, small sub-adults may be preyed upon by lions as well.
Black rhinoceros follow the same trails that elephants use to get from foraging areas to water holes. They also use smaller trails when they are browsing. They are very fast and can get up to speeds of 55 kilometres per hour (34 mph) running on their toes.
The black rhinoceros is a herbivorous browser that eats leafy plants, branches, shoots, thorny wood bushes, and fruit. The optimum habitat seems to be one consisting of thick scrub and bushland, often with some woodland, which supports the highest densities. Their diet can reduce the amount of woody plants, which may benefit grazers (who focus on leaves and stems of grass), but not competing browsers (who focus on leaves, stems of trees, shrubs or herbs). It has been known to eat up to 220 species of plants. They have a significantly restricted diet with a preference for a few key plant species and a tendency to select leafy species in the dry season. The plant species they seem to be most attracted to when not in dry season are the woody plants. There are 18 species of woody plants known to the diet of the black rhinoceros, and 11 species that could possibly be a part of their diet too. Black rhinoceros also have a tendency to choose food based on quality over quantity, where researchers find more populations in areas where the food has better quality. In accordance with their feeding habit, adaptations of the chewing apparatus have been described for rhinos. D. Bicornis has a twophased chewing activity with a cutting ectoloph and more grinding lophs on the lingual side. The black rhinoceros can also be considered a more challenging herbivore to feed in captivity compared to its grazing relatives. It can live up to 5 days without water during drought. Black rhinos live in several habitats including bushlands, Riverine woodland, marshes, and their least favorable, grasslands. Habitat preferences are shown in two ways, the amount of sign found in the different habitats, and the habitat content of home ranges and core areas. Habitat types are also identified based on the composition of dominant plant types in each area. Different subspecies live in different bushlands including, Acacia bushlands, Euclea bushlands, mixed bushlands, and dense euclea bushland. They browse for food in the morning and evening. They are selective browsers but, studies done in Kenya show that they do add the selection material with availability in order to satisfy their nutritional requirements. In the hottest part of the day they are most inactive- resting, sleeping, and wallowing in mud. Wallowing helps cool down body temperature during the day and protects against parasites. When black rhinos browse they use their lips to strip the branches of their leaves. Competition with elephants is causing the black rhinoceros to shift its diet. The black rhinoceros alters its selectivity with the absence of the elephant.
There is some variance in the exact chemical composition of rhinoceros horns. This variation is directly linked to diet and can be used as a means of rhino identification. Horn composition has helped scientists pinpoint the original location of individual rhinos, allowing for law enforcement to more accurately and more frequently identify and penalize poachers.
Rhinos use several forms of communication. Due to their bad eyesight and solitary nature, scent marking is often used to identify themselves to other black rhinos. Urine spraying occurs on trees and bushes, around water holes and feeding areas. Females urine spray more often when receptive for breeding. Defecation sometimes occurs in the same spot used by different rhinos, such as around feeding stations and watering tracks. Coming upon these spots, rhinos will smell to see who is in the area and add their own marking. When presented with adult feces, male and female rhinoceroses respond differently then when they are presented with subadult feces. The urine and feces of one black rhinoceros helps other black rhinoceroses to determine its age, sex, and identity. Less commonly they will rub their heads or horns against tree trunks to scent-mark.
To compensate for its poor eyesight, the black rhino has powerful tube-shaped ears that can freely rotate in all directions. This highly developed sense of hearing allows black rhinos to detect sound over vast distances.
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 more arid environments.
When in season the females will mark dung piles. Males will follow females when they are in season; when she defecates he will scrape and spread the dung, making it more difficult for rival adult males to pick up her scent trail.
Courtship behaviors before mating include snorting and sparring with the horns among males. Another courtship behavior is called bluff and bluster, where the rhino will snort and swing its head from side to side aggressively before running away repeatedly. Breeding pairs stay together for 2–3 days and sometimes even weeks. They mate several times a day over this time and copulation lasts for a half hour.
The gestation period is 15 to 16 months. The single calf weighs about 35–50 kilograms (80–110 lb) at birth, and can follow its mother around after just three days. Weaning occurs at around 2 years of age for the offspring. 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 to 7 years old for females, and 7 to 8 years for males. The life expectancy in natural conditions (without poaching pressure) is from 35 to 50 years.
For most of the 20th century the continental black rhino was the most numerous of all rhino species. Around 1900 there were probably several hundred thousand living in Africa. During the latter half of the 20th century their numbers were severely reduced from an estimated 70,000 in the late 1960s to only 10,000 to 15,000 in 1981. In the early 1990s the number dipped below 2,500, and in 2004 it was reported that only 2,410 black rhinos remained. According to the International Rhino Foundation—housed in Yulee, Florida at White Oak Conservation, which breeds black rhinos—the total African population had recovered to 4,240 by 2008 (which suggests that the 2004 number was low). In 1992, nine rhinoceros were brought from Chete National Park, Zimbabwe to Australia via Cocos Island. After the natural deaths of the males in the group, 4 males were brought in from USA and have since adapted well to captivity and new climate. Calves and some subadults are preyed on by lions, but predation is rarely taken into account in managing the Black Rhinoceros. This is a major flaw because predation should be considered when attributing cause to the poor performance of the Black Rhinoceros population. In 2002 only 10 West African rhinos remained in Cameroon, and in 2006 intensive surveys across its putative range failed to locate any, leading to fears that this subspecies was extinct. In 2011 the IUCN declared the Western black rhino extinct.
Under CITES Appendix I all international commercial trade of the black rhino horn is prohibited since 1977. China though having joined CITES since April 8, 1981 is the largest importer of black rhino horns. However, this is a trade in which not only do the actors benefit, but so do the nation states ignoring them as well. Nonetheless, we continue to remove the rhino from its natural environment and allow for a dependence on human beings to save them from endangerment. Parks and reserves have been made for protecting the rhinos with armed guards keeping watch, but even still many poachers get through and harm the rhinos for their horns. Many have considered extracting rhino horns in order to deter poachers from slaughtering these animals or potentially bringing them to other breeding grounds such as the US and Australia. This method of extracting the horn known as dehorning consists of tranquilizing the rhino then sawing the horn almost completely off to decrease initiative for poaching. However, rhinos use their horns to protect their young against predators and this method has been proven to be less successful because it did not decrease poaching numbers and is very expensive.
The only rhino that has recovered somewhat from the brink of extinction is the southern white whose numbers now are estimated around 14,500, up from fewer than 50 in the first decade of the 20th century. But there seems to be hope for the black rhinoceros in recovering their gametes from dead rhinos in captivity. This shows promising results for producing black rhinoceros embryos, which can be used for testing sperm in vitro.
A 2014 auction for a permit to hunt an African black rhinoceros in Namibia sold for $350,000 at a fundraiser to raise money for conservation efforts. The auction drew considerable criticism, as well as death threats.
Today, there are various threats posed to the black rhinoceros today including habitat changes, illegal poaching, and competing species. Civil disturbances such as war have made mentionably negative effects on the black rhinoceros populations in since the 1960s in countries including, but not limited to, Chad, Cameroon, Rwanda, Mozambique, and Somalia. In the Addo Elephant National Park in South Africa, the African elephant Loxotonta africana is posing slight concern involving the black rhinoceroses who also inhabit the area. Both animals are browsers however the elephant's diet consists of a wider variety of foraging capacity while the rhinoceros primarily sticks to dwarf shrubs. The black rhinoceros has been found to eat grass as well, however the shortening of its range of available food could be potentially problematic.
Black rhinoceros face problems associated with the minerals they ingest. They have become adjusted to ingesting less iron in the wild due to their evolutionary progression, which poses a problem when placed in captivity. These rhinoceros can overload on iron, which leads to build up in the lungs, liver, spleen, and small intestine. Not only do these rhinoceros face threats being in the wild, but in captivity too. Black rhinoceros have become more susceptible to disease in captivity with high rates of mortality.
Illegal poaching for the international rhino horn trade is the main and most detrimental threat. The killing of these animals is not unique to modern day society. The Chinese have maintained reliable documents of these happenings dating back to 1200 B.C. The ancient Chinese often hunted rhino horn for the making of wine cups as well as the rhino's skin to manufacture imperial crowns and belts and armor for soldiers. A major market for rhino horn has historically been in the Middle East nations to make ornately carved handles for ceremonial daggers called jambiyas. Demand for these exploded in the 1970s causing the black rhinoceros population to decline 96% between 1970 and 1992. The horn is also used in traditional Chinese medicine, and is said by herbalists to be able to revive comatose patients, facilitate exorcisms and various methods of detoxification, cure fevers, and aid male sexual stamina and fertility. It is also hunted for the superstitious belief that the horns allow direct access to heaven due to their unique location and hollow nature. The purported effectiveness of the use of rhino horn in treating any illness has not been confirmed or even suggested by medical science. In June 2007, the first-ever documented case of the medicinal sale of black rhino horn in the United States (confirmed by genetic testing of the confiscated horn) occurred at a traditional Chinese medicine supply store in Portland, Oregon's Chinatown. With rhino horn selling for nearly US$30,000 per pound, it has been argued that legalization of trade would allow horn from captive-bred rhinos to reduce the price and thus the incentive for poaching. However, most[who?] doubt that this would be successful in reducing the number of rhinos killed.
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