The Black Rhino Cows’ Horns Stand Between the Species’ Survival and its Extinction

I HAVE JUST READ A NUMBER OF SCIENTIFIC OPINIONS about the safety of cutting off a black rhino’s horns for the purpose of protecting the species from poachers. The authors claim that there were no deleterious effects and that wild populations of black rhinos were unaffected by the dehorning process.

The way in which this argument was presented, however, completely omits some very important factors to do with black rhino behaviour and the relationship that exists between black rhinos and their principle predator, the spotted hyena.

Let me fill you in, from my personal experiences in Rhodesia (now Zimbabwe), where I spent every dry season of the period (1964 – 1970) tracking black rhinos on foot, on a daily basis, from dawn to dusk, for those seven long years, darting the animals that we could and translocating 140 captured specimens to game reserves where they should have been relatively save.


After a while of such repetitive and very close association with these animals, you actually begin to think like a black rhino. But let me give you a synopsis of my experiences with these animals:

  • The black rhino is roughly half the mass of a white rhino. Adult black rhino bulls reach a shoulder height of some 5 feet (and a few inches). Big white rhino bulls reach a rough shoulder height of 6.5 feet at the shoulder.
  • Black rhinos are generally the more pugnacious of the two.
  • Black rhinos are entirely nocturnal in behaviour.

They spend the whole night foraging, often right out in the open and they find heavy thickets to hide away in during the day. They are stick-eaters and rarely eat grass. They sleep alone and soundly in these thickets from between seven and eight o’clock in the morning until three or four o’clock in the afternoon.

They begin foraging again in the late afternoon. They move into their sleeping thickets round about an hour after sunrise. So, during the day, they do nothing in their thicket retreats except sleep.

Although their thickets may comprise, entirely, the woody plant species, Acacia karoo (as is the case in Kwazulu-Natal’s Game Reserves of Umfolosi and Hluhluwe), their selection of such thickets has nothing to do with the fact that the Acacia karoo is a favourite food species of the black rhino.

How can I be so sure of this? In the Zambezi Valley the black rhino’s favourite daytime retreat comprised the thicket species Combretum elaegnoides (jesse) which is never eaten by black rhinoceros. Yet, the black rhino’s behaviour, in terms of how it behaves inside its thicket retreat during the day (sleeping soundly) is the same, no matter what the thicket’s

  • The white rhino is a It moves around sometimes in quite large family herds during the day. They do not require thicket in which to hide away during the day. They rest-up in family groups during the day in the shade of small savannah trees, feeding in the cooler hours of the morning and in the cooler hours of the afternoon. They eat at night, too, but they are far less nocturnal than the black rhino.
  • During the dry season, black rhinos do not occur beyond a range of five kilometers (three miles) from permanent water and their home-ranges are focused around their water holes. In Zimbabwe they normally drink before 9 o’clock in the evening.

Cows with small calves-at-foot hide their calves away in thick bush, or in rocky country, before venturing down to the water on their own. The calves are left, quite alone, hidden-away, some one-to-two kilometers from the water every night.

The spotted hyena is the black rhino’s principle predator. And, by hiding her calf away at this distance from the water every night, the cow protects her calf from exposure to the hyenas at the waterhole. Baby black rhinos are tiny when they are born and they remain small throughout their first year of life.

How the mother rhino persuades her baby to lie down on its own, whilst she wanders off to the water, I do not know. But she does! And she does that every night for at least the young rhino’s first year of life.

  • Black rhino cows give birth to a new calf about every thirty months. And she physically drives away her previous calf when the next calf is born. At thirty months of age the previous calf is 1,4 meters tall at the shoulder (when the mother is 1,5 meters tall at the shoulder).

At that stage the previous calf is quite capable if living independently of its mother, if there are no hyenas about. And she breaks her ties with her previous calf by becoming a wanderer. So they are then nearly the same size.

  • Under the circumstances pertaining in South Africa’s Kruger National Park and Kwazulu- Natal’s game reserves, young Black Rhino calves have a hard time surviving in the face of large spotted hyena populations. And, because in all three of these game reserves, the elephant populations are grossly excessive in number.
  • We must not forget that the mother black rhino is a solitary animal. She is not part of a big family group like the white rhinos are. And her helpless baby, when she hides it away every night, is at the mercy of every roving hyena. And, it seems that all these do-gooder scientists now want to chop off her horn, when her horn is the only weapon she has to defend her baby.

I will predict that, if the scientists get their way, in places like Kruger, Umfolosi and Hluhluwe, the black rhino will become extinct without the need of a single poacher’s gun being Already, I believe, hyenas are killing more baby black rhinos in these government game reserves than any scientist, or game ranger, is prepared to admit.

  • To test this hypothesis we have to first understand that cow black rhinos are in a state of perpetual calf-bearing. Every thirty months (two and a half years) cow rhinos give birth to a calf. And when that new calf is born, the mother rhino chases away her previous calf and takes her new calf off into the bush into a state of perpetual nomadism. And she keeps that new calf with her for the next thirty months, till her next calf is born.

That being the normal and perpetual state of affairs with black rhino cows, no mature black rhino cow should ever be without a calf-at-foot. I believe, therefore, that the chief scientist in every one of our black rhino sanctuaries, should be recording how many black rhino cows in their game reserves are wandering around without a calf-at-foot. And the numbers of cows-without-calves will tell him just how many calves are being killed by something (hyenas).

  • One of the characteristics of excessive elephant populations is that they clear-out all the vegetative cover around their waterholes for many kilometers in every direction. Go to any game reserve in Africa and see what the elephants do to the habitats within that critical five kilometers range of water!

And you will find that their negative effect on the total environment eclipses the five kilometer range which is the minimum distance that the black rhino needs to satisfy its own living requirements during the dry season. Within that distance from the water, the elephants leave nothing for the black rhinos to eat.

  • After eating out all edible plants in our game reserves for years and years, the one-time natural habitats in our game reserves have degraded into a sterile conglomerate of plants which the elephants do not eat. Those plants that survive an excessive population of elephants are inedible to elephants. Indeed, that is the only reason why those plant species survive! They are also inedible to the black rhino.
  • From the black rhino’s point of view, however, another factor has to be considered. As I have explained above, mother rhinos with babies, hide them away every night approximately two kilometers from water when she goes down to the waterhole to drink. And when the elephants have removed all the vegetative cover for several kilometers around the water, there is no plant cover left to hide those baby black rhinos from the roving eyes of the hyenas.
  • Indeed, so severe is this threat to our black rhinos that I believe any game reserve that has been set aside to protect black rhinos should be required to remove all its spotted hyenas. And certainly, game reserves that contains both black rhinos and spotted hyenas, should never be allowed to dehorn the black rhino cows. The cows’ horns are the only things that stand between survival of the species, and its extinction.

Ron Thomson. CEO – TGA.

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