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White rhinoceroses are found in grassland and savannah habitat. Herbivore grazers that eat grass, prefer the shortest grains, the white rhinoceros is one of the largest pure grazers. It drinks twice a day if water is available, but if conditions are dry it can live four or five days without water. It spends about half of the day eating, one third resting, and the rest of the day doing various other things. White rhinoceroses, like all species of rhinoceros, love wallowing in mudholes to cool down. White rhinoceroses produce sounds which include a panting contact call, grunts and snorts during courtship, squeals of distress, and deep bellows or growls when threatened. Threat displays (in males mostly) include wiping its horn on the ground and a head-low posture with ears back, combined with snarl threats and shrieking if attacked. The white rhinoceros is quick and agile and can run at 50 km/h (31 mph). White rhinoceroses live in crashes or herds of up to 14 animals (usually mostly female). Sub-adult males will congregate, often in association with an adult female. Most adult bulls are solitary. Dominant bulls mark their territory with excrement and urine. The dung is laid in well defined piles. It may have 20 to 30 of these piles to alert passing rhinoceroses that it is his territory. Another way of marking their territory is wiping their horns on bushes or the ground and scrapes with its feet before urine spraying. They do this around 10 times an hour while patrolling territory. The same ritual as urine marking except without spraying is also commonly used. The territorial male will scrape-mark every 30 m (98 ft) or so around its territory boundary. Subordinate males do not mark territory. The most serious fights break out over mating rights to do with a female. Female territory is overlapped extensively and they do not defend it.
Females reach sexual maturity at 6–7 years of age while males reach sexual maturity between 10–12 years of age. Courtship is often a difficult affair. The male stays beyond the point where the female acts aggressively and will give out a call when approaching her. The male chases and or blocks the way of the female while squealing or wailing loudly if the female tries to leave his territory. When ready to mate the female curls its tail and gets into a stiff stance during the half hour copulation. Breeding pairs stay together between 5–20 days before they part their separate ways. Gestation occurs around 16–18 months. A single calf is born and usually weighs between 40 and 65 kg (88 and 140 lb). Calves are unsteady for their first 2 to 3 days of life. When threatened the baby will run in front of the mother, who is very protective of her calf and will fight for it vigorously. Weaning starts at 2 months, but the calf may continue suckling for over 12 months. The birth interval for the white rhino is between 2 and 3 years. Before giving birth the mother will chase off her current calf. White rhinos can live to be up to 40–50 years old. Adult white rhinos have no natural predators due to their size, and even young rhinos are rarely attacked due to the mother's presence or preyed on due to their tough skin.
The captive northern white rhino population consists of only four animals and is maintained in two zoological institutions in the U.S.A. and the Czech Republic. The zoo population is declining, and is possibly not viable. Northern whites have rarely reproduced in captivity. Therefore, those four capable of breeding have been returned to their former range in Kenya where they are held in partial captivity.
The white rhinoceros of today was said to be likely descended from Ceratotherium praecox which lived around 7 million years ago. Remains of this white rhino have been found at Langebaanweg near Cape Town.[6] A review of fossil rhinos in Africa by Denis Geraads has however suggested that the species from Langebaanweg is of the genus Ceratotherium, but not Ceratotherium praecox as the type specimen of Ceratotherium praecox should, in fact, be Diceros praecox, as it shows closer affinities with the black rhinoceros Diceros bicornis.[7] It has been suggested that the modern white rhino has a longer skull than Ceratotherium praecox to facilitate consumption of shorter grasses which resulted from the long term trend to drier conditions in Africa.[8] However, if Ceratotherium praecox is in fact Diceros praecox, then the shorter skull could indicate a browsing species. Teeth of fossils assigned to Ceratotherium found at Makapansgat in South Africa were analysed for carbon isotopes and the researchers concluded that these animals consumed more than 30% browse in their diet, suggesting that these are not the fossils of the extant Ceratotherium simum which only eats grass. It is suggested that the real lineage of the white rhino should be; Ceratotherium neumayri ? Ceratotherium mauritanicum ? C. simum with the Langebaanweg rhinos being Ceratotherium sp. (as yet unnamed), with black rhinos being descended from C. neumayri via Diceros praecox.[7] It is likely then that the ancestor of both the Black and the White rhinos was a mixed feeder, with the two lineages then specialising in browse and graze, respectively.
There are two subspecies of white rhinos; the southern white rhinoceros (Ceratotherium simum simum) and the northern white rhinoceros. As of 31 December 2007, there were an estimated 17,480 southern white rhino in the wild (IUCN 2008), making them the most abundant subspecies of rhino in the world. South Africa is the stronghold for this subspecies (93.0%), conserving 16,255 individuals in the wild in 2007 (IUCN 2008). There are smaller reintroduced populations within the historical range of the species in Namibia, Botswana, Zimbabwe and Swaziland, while a small population survives in Mozambique. Populations have also been introduced outside of the former range of the species to Kenya, Uganda and Zambia. Wild-caught southern whites will readily breed in captivity given appropriate amounts of space and food, as well as the presence of other female rhinos of breeding age. For instance, 91 calves have been born at the San Diego Zoo Safari Park since 1972. However, for reasons that are not currently understood, the rate of reproduction is extremely low among captive-born southern white females. Northern white rhinoceros Main article: Northern white rhinoceros The northern white rhinoceros (Ceratotherium simum cottoni), formerly found in several countries in East and Central Africa south of the Sahara, is considered Critically Endangered or Extinct in the Wild. Recent research has suggested that the northern white rhinoceros might be a distinct species, and should therefore be renamed Ceratotherium cottoni. Distinct morphological and genetic differences suggest that the two proposed species have been separated for at least a million years. As of 2006, there were only four northern white rhinos left in the wild according to the World Wide Fund for Nature.[13] However, in June 2008 it was reported that the subspecies could be extinct in the wild since none of these four known remaining individuals has been seen since 2006. On 20 November a herd of 4 northern white rhinos from Dvur Králové Zoo was transported to Kenya. The Czech Dvur Králové Zoo was the world's only zoo where northern white rhinos reproduced offspring. But as the last offspring were born in 2000, the zoo management decided to stimulate the Rhino's sexual appetite by putting them back into their natural habitat. The agreement with Kenya government expects the Rhinos never to be returned to the Czech Republic. Reportedly they are supposed to be heavily guarded to ensure safety from poachers. The northern white rhino formerly ranged over parts of north-western Uganda, southern Chad, south-western Sudan, the eastern part of Central African Republic, and north-eastern Democratic Republic of the Congo. Poachers reduced their population from 500 to 15 in the 1970s and 1980s. From the early 1990s through mid 2003, the population recovered to more than 32 animals. Surveys in 2000 indicated that the population had started recovering, with 30 animals confirmed in 2000, and possibly six others. Since mid-2003, poaching had intensified and reduced the wild population to only 5 to 10 animals (7 actual count worldwide).
The black rhinoceros or hook-lipped rhinoceros (Diceros bicornis), is a species of rhinoceros, native to the eastern and central areas of Africa including Kenya, Tanzania, Cameroon, South Africa, Namibia, Zimbabwe, and Angola. Although the rhino was referred to as black, it is actually more of a grey/brown/white color in appearance. The other African rhinoceros is the white rhinoceros (Ceratotherium simum). These common names are misleading, as those two species are not really distinguishable by color. The word white in the name "white rhinoceros" is a mistranslation of 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 overall is classified as critically endangered, and one subspecies, the Western Black Rhinoceros, was declared extinct by the IUCN in 2011.
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 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 (4,850–6,380 lb).[4] 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 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. Skin color depends more on local soil conditions and the rhinoceros' wallowing behavior than anything else, so many black rhinos are typically not truly black in color. The black rhino is smaller than the white rhino, and has a long, pointed, and prehensile upper lip, which it uses to grasp leaves and twigs when feeding. White rhinoceros has square lips used for eating grass. The black rhinoceros can also be distinguished from the white rhinoceros by its smaller skull and ears. Their thick layered skin protects the rhino from thorns and sharp grasses. Their skin harbors external parasites, such as mites and ticks, which are eaten by oxpeckers and egrets that live with the rhino. 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.[8] Black rhinos have poor eyesight, relying more on hearing and smell. Their ears possess a relatively wide rotational range to detect sounds. An excellent sense of smell alerts rhinos to the presence of predators.
Black rhinos in Ngorongoro crater, Tanzania 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[2] living in Africa. During the latter half of the 20th century their numbers were severely reduced from an estimated 70,000[9] 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, the total African population had recovered to 4240 by 2008 (which suggests that the 2004 number was low). 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. 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. The black rhinoceros had been pushed to the brink of extinction by illegal poaching for their horn, and to a lesser extent by loss of habitat. A major market for rhino horn has historically been in the Middle East 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, cure fevers, and aid male sexual stamina and fertility.[13] The purported effectiveness of the use of rhino horn in treating any illness has not been confirmed 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. Behavior This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (November 2011)
Although they are typically solitary animals, with the exception of coming together to mate, mothers and calves will sometimes congregate in small groups for short periods of time. Males are not as sociable as females, although they will sometimes allow the presence of other rhinos. 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. In the Serengeti home ranges are around 43 to 133 km2 (17 to 51 sq mi), while in the Ngorongoro it is between 2.6 to 44 km2 (1.0 to 17 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.[citation needed] 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.[citation needed] 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.[14] Adult rhinos normally have no natural predators, but they may fall prey to crocodiles in exceptional circumstances.[16] Black rhinoceros follow the same trails as 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 56 kilometres per hour (35 mph) running on their toes.
The black rhinoceros is a herbivorous browser that eats leafy plants, branches, shoots, thorny wood bushes, and fruit. Their diet can reduce the amount of woody plants, which may benefit grazers (who eat grass), but not competing browsers. It has been known to eat up to 220 species of plants. It can live up to 5 days without water during drought. Black rhinos live in primarily grasslands, savannas, and tropical bushland habitats. They browse for food in the morning and evening. In the hottest part of the day they are most inactive- resting, sleeping, and wallowing in the mud. Wallowing helps cool down body temperature during the day and protects against parasites. If mud is not available rhinos will wallow in dust. Drinking water is most common in the afternoon. When black rhinos browse they use their lips to strip the branches of their leaves.
Black rhino in Ngorongoro crater, Tanzania 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. Less commonly they will rub their heads or horns against tree trunks to scent-mark. Different types of vocalizations have also been observed. Growls and trumpets may be used during a fight. A long snort indicates anger, while sneeze-like calls are used as an alarm to danger. Short snorts with pricked ears and wrinkled nostrils are a startle reaction to a newcomer. A high-pitched "wonk" has been described for when they are fearful. A high-pitched scream has been observed in times of terror. "Mmwonk", a deep, resonant sound is a sign of contentment. Squeak, done with different tones and intonations may mean "I'm lost", "Where are you?", "I'm over here", or other signals that are not yet understood. Breathing speeds can be used to communicate greetings, anxiety, and reassurance. A puffing snort is a common greeting when males and females encounter one another.[citation needed] Body language also a form of black rhinoceros communications. A bull will sometimes display an aggressive ritual towards a potential rival. They will smell, spray repeatedly, scrape, trample, and bash with their heads in bushes. They may also snort in an attack posture. When their tail is up, it may indicate one of several things: curiosity, alarm, or sexual receptivity. Erect ears also indicate curiosity, and flat ears express anger.
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 following females that are in season will follow her; when she defecates he will scrape and spread the dung, making it more difficult for any other 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 an hour. The gestation period is 15 to 16 months. The single calf weighs about 35–50 kg 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 5–7 years old for females, and 7–8 years for males. The life expectancy in natural conditions (without poaching pressure) is from 35–50 years.
Despite the continuing threat to rhinos from poaching for their horns, population figures have been increasing. At the beginning of the 20th century there were 500,000 rhinos; in 1970 there were 70,000; today, there are fewer than 29,000 rhinos surviving in the wild. Between 1970 and 1992, large-scale poaching caused a dramatic 96% collapse in numbers of the Critically Endangered black rhino. 95% of all the rhinos in the world have now been killed. After the poaching wars of the late 1980s and early 1990s and up until the end of 2007, white rhino numbers had been increasing by around 9.5% a year, and by around 6% per year for black rhinos, thanks to conservation efforts. These figures are based on numbers published in 2010 by the IUCNThe white rhinoceros or square-lipped rhinoceros (Ceratotherium simum) is one of the five species of rhinoceros that still exist. It has a wide mouth used for grazing and is the most social of all rhino species. The white rhino consists of two subspecies: the southern white rhino, with an estimated 17,460 wild-living animals at the end of 2007 (IUCN 2008), and the much rarer northern white rhino. The northern subspecies has very few remaining, all in captivity.
