Dave Taylor's African Safari: Trophic Level II - The Herbivores - Black Rhinoceros

Dave Taylor's African Safari: Trophic Level II - The Herbivores - Black Rhinoceros - Page 42

Trophic Level II - The Herbivores
Black Rhinoceros
Page 42

Diceros bicornis

Length: 290-375 cm (9.5-12’)

Height: 137-180 cm (54-71")

Tail: 60-70 cm (24-28")

Weight: 700-1 400 kg (1,540-3,086 lb.)

Status: Endangered. There are less than 3,000 left and the numbers are declining despite protective measures! Some 90% of Africa’s black rhinos were killed by poachers between 1970 and 1995. They were killed for their horns. The horns were then sold, primarily, to the country of Yemen where they were used to make handles for ceremonial daggers.

Habitat: Black rhinos live in a variety of habitats. Although largely eliminated by poaching and through eradication schemes in the 50s and 60s, they may still be found in some protected parts of their former range.

There are two species of rhino living in Africa today. The white rhino is a grazer and is found in areas where grass is available. The black rhino is a browser and is found where there are trees and shrubs. This includes semi-desert thornbush, wooded savannas, montane forests, wetlands and open savannas. (From fossil records, white rhinos are known to have once inhabited the Serengeti-Mara region but they have been extinct here for at least several hundred years.)

Food: Black rhinos eat over 200 different plants including herbs and shrubs. They have a prehensile lip that curls around a leaf or the branch of the tree and lets them feed selectively on the best browse available. Large molars grind up even the tough fibrous wood that they eat. Horns are used to break off branches or to remove bark. They will also use their horns to dig up mineral-rich earth. On average, black rhinos eat about 23 kilograms (51 lb.) of food a day.

Rhinos need to drink every four or five days. They can get some of their liquid needs from chewing water-rich succulent tree leaves and branches.

During hot spells, a rhino might travel 5 to 15 kilometers (3-9 miles) a day to drink and wallow. Like the elephant, but not so successfully, rhinos will dig for water in dry sandy riverbeds during droughts.

Social System: The black rhino's social system has been well documented. Sadly, there are so few of these animals left that today only greatly reduced remnant populations exist. It is difficult to say for certain what their social structure is like today.

In Ngorongoro Crater, where there were 150 rhinos in 1980, there are now only 15 left. In those days of high numbers, the rhinos were quite social and mature bulls would be quite tolerant of other bulls whose range overlapped theirs. Groups of four or five were a common site and one group of 13 was recorded. The crater floor is mostly grassland and the rhinos roamed over it selecting to feed on young trees.

In Serengeti National Park, there were 700 rhinos in 1980. Since then, the population has been reduced to less than 15. In this much larger park, both sexes were solitary and bulls maintained distinct territories in woodland habitats. (See below for more on social systems.)

Today, there are less than 3,300 black rhinos in Africa. In the late 1960s there were 70,000.

Behavior: Black rhino bulls are usually found by themselves unless they are courting a cow. Cows are either alone or accompanied by their last calf. Sometimes, a second, older calf will accompany her as well. This second calf may not be hers but that of another female. Unlike the more social white rhino, the black is considered to be a solitary animal.

In areas of high density, several black rhinos may congregate around a resource, either an estrus female, wallow, or patch of food.

Black rhinos normally occupy a territory and follow well defined paths through it. Throughout their territory, they create dung middens which they add to and inspect daily. Both sexes will add to the midden. They also horn it and then take slow kicks at it, scattering the dung behind them. They leave behind them a scent trail that lets other rhinos either follow them or avoid them.

Finding Their Way

Bull rhinos also urine-spray. They back up to a bush and spray it two to five times. This is done only by mature territorial bulls.

Mature bulls will display to each other by walking stiff-legged and broadside to their opponent. This shows off their horn and body size. When they fight, they use their horns like staves, trying to determine which animal is stronger. In serious fights or when warding off an enemy, they hook and stab with the horn. A rhino’s horn is made up of keratin, a tough protein substance that resembles matted hair.

A black rhino will sometimes feint an attack. The animal rushes forward making puffing shrieks. It will then stop abruptly or turn away. They can reach a speed of 50 kilometers per hour (30 mph).

Rhinos make a variety of sounds including snorts, puffing shrieks and grunts. It has recently been discovered that both black and white rhinos produce infrasonic sounds in the range of 5 to 75 hertz (humans can only hear 100 hertz). These low frequency sounds resemble the ones made by hippos and elephants and are likely a means of communicating. As yet, their exact function has not been discovered but it is possible that they are able to locate each other at great distances.

Finding A Mate

When a female is in estrus her urine contains chemicals that alert the bull. He will test her urine and perform a flehem as he analyzes it. Finding a cow in estrus is one thing. Convincing her to mate is another. He will follow her around for several days, gradually getting closer to her as he wins her confidence. She will often turn on him and threaten him, but the threats lessen until she finally allows him to mate.

The cow gives birth to one calf 15 or 16 months after conception. Females reach maturity around 7 years old; males between 10 and 12 years. Females are often bred before they reach full maturity. They will have a calf every 2 to 4 years. Although rhinos can live up to 40 years, they have one of the lowest recruitment birth rates of any species.

Expectant cows seek an isolated spot and will drive off their previous offspring. The rejected calf will often seek the company of another female, who may have a young calf of her own.

Newborns can stand within 10 minutes. They follow their mothers very closely and when danger threatens, will stand rear to rear with her, to ward off the threat. Lions and spotted hyenas are the biggest danger a calf faces. A pack of spotted hyenas are especially dangerous. One or two can so distract a cow that she will be chasing one off while the other goes in for the kill.

Black rhino calves always run behind their mothers while white rhino calves are always in front.

Predators: Lions and spotted hyenas will prey on calf rhinos.

Man has exterminated the rhino from much of its former range. Originally in Kenya and Tanzania, European farmers viewed this species as vermin and thousands were killed to clear the land of this "beast". In more recent times, poaching has brought the rhino almost to the brink of extinction. Kenya was home to 3,000 black rhinos in the early 70s. Ngorongoro Crater had 150 alone. Today, Kenya has less than 500 and Ngorongoro is down to about 15. Seeing a rhino in the Serengeti-Mara is a rare event.

Tanzania has a little over 100 black rhinos alive today.

In all of Africa, there are approximately 2,200 black rhino and 5,000 white rhino.

The main cause of the decline is poaching. Poachers sell the horns to Yemen where it is made into dagger handles.

Parasites and Oxpeckers

Often, rhinos will have open wounds on their sides. These wounds are infected with a microscopic parasitic worm (filaria sp. Name Stephanofilaria dinniki) which feed on the rhino’s blood. Oxpeckers help cure the infection by feeding on the ticks. It is the blood they are after but the ticks are filled with it, so by eating the ticks, the oxpecker gains the food it needs. Rhinos tolerate their attention and both species benefit from this symbiotic relationship. The oxpecker gets a meal and the rhino is warned by the birds when danger approaches.

A parasitic worm appears to cause the lesion. They need blood-sucking insects and ticks to complete their life cycle. Many of these insects and ticks are associated with rhinos. What is believed to happen is this: a tick or insect bites the rhino, infecting it with the parasite. The parasite migrates through the rhino’s body until it comes to a spot where it can create the festering sore. All adult rhinos appear to get these sores at the same place. The festering sore then attracts more ticks and insects which the parasite enters to complete its life cycle. This begins the cycle again.

Select a Page:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42