RHINO

Facts

White Rhino

The White Rhinoceros is the largest of the five living species of Rhinoceros. By mean body mass, the White Rhinoceros falls behind only the three extant species of Elephant as the largest land animal and terrestrial mammal alive today. It weighs slightly more on average than a Hippopotamus despite a considerable mass overlap between these two species. It has a massive body and large head, a short neck and broad chest.

The head and body length is 3.7–4 m (12.1–13.1 ft) in bulls and 3.35–3.65 m (11.0–12.0 ft) in cows, with the tail adding another 70 cm (28 in), and the shoulder height is 170–186 cm (5.58–6.10 ft) in the bull and 160–177 cm (5.25–5.81 ft) in the cow. The bull, averaging about 2,000–2,300 kg (4,410–5,070 lb) is heavier than the cow, at an average of about 1,600–1,700 kg (3,530–3,750 lb). On its snout it has two horn-like growths, one behind the other. These are made of solid keratin, in which they differ from the horns of bovids (cattle and their relatives), which are keratin with a bony core, and Deer antlers, which are solid bone.

The front horn is larger and averages 60 cm (24 in) in length, reaching as much as 166 cm (65 in) but only in cows. The White Rhinoceros also has a noticeable hump on the back of its neck. Each of the four stumpy feet has three toes. The colour of the body ranges from yellowish-brown to slate grey. Its only hair is the ear fringes and tail bristles. White Rhino have a distinctive broad, straight mouth which is used for grazing. Its ears can move independently to pick up sounds, but it depends most of all on its sense of smell. The olfactory passages that are responsible for smelling are larger than their entire brain. The White Rhinoceros has the widest set of nostrils of any land-based animal.

White Rhino are found in grassland and savannah habitat. Herbivore grazers that eat grass, preferring 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. Like all species of Rhinoceros, White Rhino enjoy wallowing in mud holes to cool down. The White Rhinoceros is thought to have changed the structure and ecology of the savanna’s grasslands. Comparatively, based on studies of the African Elephant, scientists believe the White Rhino is a driving factor in its ecosystem. The destruction of the megaherbivore could have serious cascading effects on the ecosystem and harm other animals.

White Rhino produce sounds that include a panting contact call, grunts and snorts during courtship, squeals of distress, and deep bellows or growls when threatened. Threat displays (in bulls 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 differences in these calls aid the White Rhino in identifying each other and communicating over long distances. The WhiteRhinoceros is quick and agile and can run 50 km/h (31 mph).

White Rhino live in crashes or herds of up to 14 animals (usually mostly cows). Sub-adult bulls will congregate, often in association with an adult cow. 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 White Rhino that it is his territory. Another way of marking their territory is wiping their horns on bushes or the ground and scraping with their feet before urine spraying. They do this around ten times an hour while patrolling territory. The territorial bull will scrape-mark every 30 m (100 ft) or so around his territory boundary. Subordinate bulls do not mark territory. The most serious fights break out over mating rights with a cow. Cow territory overlaps extensively, and they do not defend it.

Cows reach sexual maturity at 6–7 years of age while bulls reach sexual maturity between 10 and 12 years of age. Courtship is often a difficult affair. The bull stays beyond the point where the cow acts aggressively and will give out a call when approaching her. The bull chases and or blocks the way of the cow while squealing or wailing loudly if the cow tries to leave his territory. When ready to mate, the cow curls her 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. The gestation period of a White Rhino is 16 months. A single calf is born and usually weighs 40–65 kg (88–143 lb). Calves are unsteady for their first two to three days of life. When threatened, the baby will run in front of the mother, which is very protective of her calf and will fight for it vigorously. Weaning starts at two months, but the calf may continue suckling for over 12 months. The birth interval for the White Rhino is between two and three years. Before giving birth, the mother will chase off her current calf. White Rhino can live to be up to 40–50 years old.

Due to their size, adult White Rhino have no natural predators (other than humans) and even young Rhino are rarely attacked or preyed on due to the mother’s presence and their tough skin.

Black Rhino

An adult Black Rhinoceros stands 132–180 cm (52–71 in) high at the shoulder and is 2.8–3.75 m (9.2–12.3 ft) in length. An adult typically weighs from 800 to 1,400 kg (1,760 to 3,090 lb), however unusually large male specimens have been reported at up to 2,896 kg (6,385 lb). The cows are smaller than the bulls. Two horns on the skull are made of keratin with the larger front horn typically 50 cm (20 in) long, exceptionally up to 135.9 cm (53.5 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 defence, intimidation, and digging up roots and breaking branches during feeding. The Black Rhino is smaller than the White Rhino and close in size to the Javan Rhino of Indonesia. It has a pointed and prehensile upper lip, which it uses to grasp leaves and twigs when feeding, whereas 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.

Their thick-layered skin helps to protect Black Rhino from thorns and sharp grasses. Their skin harbours 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. It is commonly assumed that Black Rhino have poor eyesight, relying more on hearing and smell. However, studies have shown that their eyesight is comparatively good, at about the level of a rabbit. Their ears have a relatively wide rotational range to detect sounds. An excellent sense of smell alerts Rhino to the presence of predators.

Black Rhino are generally thought to be solitary, with the only strong bond between a mother and her calf. In addition, bulls and cows 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 cows larger than those of bulls, especially when accompanied by a calf. Black Rhino] 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 Rhino have a reputation for being extremely aggressive, and charge readily at perceived threats. They have even been observed to charge tree trunks and termite mounds. Black Rhino will fight each other, and they have the highest rates of mortal combat recorded for any mammal: about 50 percent of males and 30 percent of females die from combat-related injuries. Adult Rhino normally have no natural predators, due to their imposing size, thick skin, and deadly horns. However, adult Black Rhino have fallen prey to Crocodile in exceptional circumstances. Calves and, very seldom, small sub-adults may be preyed upon by Lion as well.

Black Rhino follow the same trails that Elephant 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.

While it was assumed all Rhinoceros are short-sighted, a study involving Black Rhinoceros retinas suggests they have better eyesight than previously assumed.

Black Rhino are herbivorous browsers that eat leafy plants, twigs, branches, shoots, thorny wood bushes, small trees, legumes, fruit, and grass. 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 number 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 Rhino 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. Black Rhino show a preference for Acacia species, as well as plants in the family Euphorbiaceous. They can live up to 5 days without water during drought.

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 Rhino browse they use their lips to strip the branches of their leaves. Competition with Elephant 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 Rhino, allowing for law enforcement to more accurately and more frequently identify and penalize poachers.

Black Rhino use several forms of communication. Due to their solitary nature, scent marking is often used to identify themselves to other Black Rhino. Urine spraying occurs on trees and bushes, around water holes and feeding areas. Cows urine spray more often when receptive for breeding. Defecation sometimes occurs in the same spot used by different Black Rhino, such as around feeding stations and watering tracks. Coming upon these spots, Rhino will smell to see who is in the area and add their own marking. When presented with adult faeces, bulls and cows respond differently than when they are presented with subadult faeces. The urine and faeces 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.

The Black Rhino has powerful tube-shaped ears that can freely rotate in all directions. This highly developed sense of hearing allows Black Rhino 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 cows will mark dung piles. Bulls will follow cows when they are in season; when she defecates he will scrape and spread the dung, making it more difficult for rival adult bulls to pick up her scent trail. Courtship behaviours before mating include snorting and sparring with the horns among males. Another courtship behaviour is called bluff and bluster, where the Black 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 for a Black Rhino is 15 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 Hyena and Lion. 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 is from 35 to 50 years.