Running Wild

by Bristow, David;

  Animal biologists at Onderstepoort have long puzzled over why zebras appeared to be immune to African horse sickness while horses are extremely vulnerable. They noted the distribution of the disease almost perfectly overlapped the historic range of the plains zebra. That pointed to an evolutionary explanation: that the two organisms, zebra and virus, co-evolved. Zebras that developed immunity survived to pass on the necessary genes to their offspring. And yet during all his years of running free, Zulu, who was clearly not a zebra, never succumbed to the disease that is almost always fatal for horses.

  There were no people around to witness it, but the curious case of Zulu and the time he was bitten by a snake and survived would have informed any aspiring naturalist. Had they sought an answer in the volumes of evolutionary biology they would have been disappointed. The truth was completely unexpected but could hardly have been more elementary.

  Equids have excellent, almost all-round vision. They also have a height advantage over most other animals to see things on the ground or in the grass, not least of all snakes. Horsey folk will vouch that, with a few notable exceptions, horses are extremely inquisitive animals and sometimes dangerously so. If, for example, they see a python in the grass they will approach cautiously, standing over it and staring. A large python will generally lie still when danger comes calling, relying on camouflage or, if detected, its intimidating size to act as a deterrent.

  Most other snakes would almost always flee, “hearing” as they do by picking up vibrations in the ground – excepting for puff adders which rely on camouflage alone and will strike in a flash, mouth fully agape with fearsome fangs ready, armed and loaded with potent cytotoxin. Most serious snakebites in Africa are inflicted by puff adders. If not treated hastily, a good bite will lead to atrocious flesh decay and even the loss of a limb.

  In spite of his height advantage, Zulu did not see the three-metre-long rope of black death as it lay in the lee of a fallen rain tree. As he stepped over the log, the serpent’s coffin-shaped head opened like an old clamshell phone to reveal its ominous black gape and white needle fangs.

  As its teeth sunk into the horse’s lower leg, the serpent coiled its upper body around the leg in order to protect itself. Zulu jumped with fright more than pain, then kicked and stomped trying to shake off the writhing reptilian accessory. He reared and with the second stomp broke the black mamba’s hold. The snake shot off out of harm’s way and then reared up, threatening with its partial hood spread and menacing mouth wide open, hissing as it swayed back and forth.

  A black mamba has the most advanced poison delivery system of any snake. For its large size the fangs are not particularly long, only about one-and-a-half centimetres, but they are located at the very front of its wide-hinged mouth that seldom misses with a strike. Just one pinhead-size drop of its neurotoxic venom is more than enough to kill a large animal in less than one hour. The poison causes the nervous system and muscles to shut down and death will come from a heart attack or asphyxiation, or both. There is a saying that if a black mamba bites you there is only one remedy: sit on your haunches, bend your head as far under as you can and kiss your sorry butt goodbye.

  Zulu was unnerved by the incident. Within minutes of being bitten his head felt dull, extremely heavy and it dropped down to his knees. Progressively he began to perspire and salivate uncontrollably. His eyelids drooped and his movements became lethargic. His breath was short, heart racing, his movements laboured and he had trouble walking without stumbling. He leaned up against the column of a termite mound that rose up next to a large jackalberry tree, not sure he could keep himself from falling over.

  His females looked on, concerned that their protector was in dire trouble. His mate paid him close attention, nudging him fretfully with her muzzle. He was in dire trouble, but when it came to being bitten by deadly snakes, Zulu had two advantages over most other creatures.

  Being an equid, the leg just above the fetlock where Zulu had been struck has virtually no flesh and therefore a very limited blood supply. Once bitten the venom would not travel nearly as fast into his body as it would in the case of a human being bitten on the lower leg. This meant the symptoms of the bite were slow to take effect.

  Also, Zulu had spent three years at Karl Plaas being injected with snake venom, mostly of the same predominantly neurotoxic type delivered by cobras and mambas, and developing antibodies. The sturdy black horse had been – as the old Arlo Guthrie rap-sheet went – injected, inspected, detected, infected, neglected and see-lected, and was as close to having acquired immunity from snake bites as was biologically possible.

  Still, that did not mean he was completely in the clear. An hour after being bitten he had collapsed in a blind, shaking heap on the bare mound of the termite nest. There he lay for the rest of the day with his herd milling around, not sure what was going on or what they could do about it. Among the trees, as evening approached, they would be easy lion bait.

  When Zulu stopped moving and the sun slid into the tree canopy, instinctively the herd moved off to stand in open ground where an ambush was less likely. The ground underneath was a tangle of dry burr-bristle grass that was about as palatable as rolls of barbed wire and generally about as disagreeable. What with the discomfort of constant thirst and the urge to find a drinking place, the pricks of the burrs and the attentions of biting flies out there in the open, all they could do was stand and wait. All through the night they waited, jumping at any and every sudden sound.

  Next morning Zulu was still lying prone on the ground and the herd gathered around, the females anxiously nuzzling him and softly nibbling his flanks. The warming sun of late morning seemed to ignite a spark in the old nag and he gave a shake, lifted his head with some effort and snorted. By that time he was desperately thirsty and ever so slowly raised himself, one reluctant joint at a time, looking more like a comical camel than a noble horse. A sense of joy gripped the herd and the young ones, which had been sullen since the previous evening, began nipping and headbutting one another.

  The bite had dealt a hammer blow to Zulu’s body and he ached all over, like malaria on top of the worst hangover ever. He had a pounding koppestamp and tongue-thickened nadors when it feels like every cell in your body has shrivelled and urgently needs water. It is no coincidence that the word “intoxication” means to be poisoned, originally referring to being shot with a poison arrow or bitten by a poisonous snake. Walking on stiff, painful legs he had only one thing on his aching brain – water. The entire herd had been without water for going on two days; they had been on their way to the Majale to find water when fate had struck.

  They trudged through the late morning haze, the females encouraging the younger zebras, pushing their rumps and nuzzling their legs. Finally they neared the riverbank where they faced two problems. One was that it was late and would soon be getting dark when they would prefer to be settling in at some safe spot for the night rather than looking for water at hunting time. The other was that any remaining waterhole in the riverbed would be like the only saloon in the Kalahari serving cold beer with bar predators in close attendance.

  When the horse safari business started there had been no resident male lions in Mashatu. However, there had always been a nomadic population that ranged along the Limpopo River, often crossing the Shashe into Zimbabwe for easy pickings around the villages there. But as often as not, farmers would shoot them on sight. Killing a lion is still widely regarded as a sign of virile manhood, although the custom comes from a time when it was done with a spear rather than a high-powered rifle with telescopic sights.

  The general absence of lions was good for the horses as well as the other plains game that are the principal lion food in the savanna ecosystem. But every ecosystem needs its apex predators to remain healthy. Take out the top predators and there follows a cascade of consequences. It starts with a slow but steady increase in the numbers of smaller predators such as jackals and baboons, smaller cats and “mesopredators” like genets and mongooses.
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  Herbivores proliferate and have a knock-on effect on the insect populations and on the vegetation, cropping off all new growth and denuding the riverbanks, which renders them susceptible to erosion – which is exactly what had happened to the Limpopo’s banks prior to the great storm of 2000. Huge trees that had stood rooted for centuries were washed away. Then suddenly – or so it would seem – there would be a plague on the land, and all because there were no lions.

  At Mashatu, the most obvious effect of having no resident male lions was that the hyenas took over as the dominant predators. As their numbers grew they became progressively bolder, loping around brazenly – even through villages during daytime. However, increased safari activity and conservation allowed two mature male lions to take up residence in Mashatu: one-eyed Matswane and his brother, scar-nosed Dumatau. A single male lion is formidable but a coalition of two siblings in their prime is all but invincible. Almost immediately things started to change, the most noticeable being that the hyenas went underground and returned to their conniving nocturnal ways.

  For three years life was good for the brothers and during that time the more dominant Matswane sired many cubs. The flying claw of a lioness had blinded one of his eyes when he stepped in to break up a jealous spat between two pride females. The two male lions specialised in seizing eland, the largest antelope, which gave them more than enough food for three or four days at a time.

  One time they went walkabout into Zimbabwe, as male lions will when there are no pride females in oestrus, but only Matswane returned. Possibly sensing the opportunity, several months later two younger male lions moved into his turf and immediately challenged the king. Being larger, stronger and more experienced, he easily sent them packing, but he knew they’d be back. It was around this time that Zulu encountered the black mamba.

  On the far bank of the river, Matswane’s eyes glinted in the low light, one gold and the other silvery-blue. He was poised squat on his haunches like the Lion matchbox icon, looking disdainful but keenly watching the approaching zebras. They were in such a weakened state that he could have ambled over and without much effort taken any one of them. But, lucky for them, the king did not know it. In the riverbed between them was a pool of scummy water.

  The herd would advance no closer and just have to wait and hope for an intervention. They barely had the energy to complain: qua-ha, qua-ha. As the last embers of the sunlight glimmered and started fading to lifeless ash, a small herd of elephants approached the water, only to encounter a male lion in their path. Matswane stood up to confront them and the elephants charged, trumpeting as they came. The lion snarled once before losing his composure and fleeing into the darkness.

  A thirsty adult elephant can drink 200 litres a day. It took ages for this dirty dozen to fill their tanks, water slowly siphoning into the pool from the aquifer below. Zulu and his herd waited. A half-moon projected a latticework of shadows on the pale riverbed by the time the lead horse made his way gingerly down, slipping on the steep bank and walking cautiously to the pool. Only when he had slaked his thirst and taken up a guard position did he give the call and the rest of his herd rushed down.

  It was a gargantuan battle when Matswane was finally dethroned by the new coalition and sent packing to lick his wounds in the land of solitary nomads. The new ruling elite built their own empire, which broke up into successive new prides as each new batch of males matured and was forced out to found their own dynasties. The balance was restored in the Tuli. Lion muti had been applied and the land had healed.

  16

  Pula

  A HORSE WALKS INTO A BAR. The barman asks, “So why the long face?”

  It’s a great joke that never gets tired because it’s true: horses have exceptionally long faces relative to their overall size, and for very good reason. Along with an extremely long and light springing foot, the other significant physiological adaptation to their original home on the arid Asian steppes was – as the climate there changed – from browsing to grazing; from eating highly nutritious leaves and fruits of bushes to a much less nourishing diet of grass.

  The proto-horse Hyracotherium also developed a progressively larger brain as it needed to be increasingly precise in order to efficiently select suitable forage. The small amount of goodness in the stems is contained inside tough cellulose casings which are indigestible for most grazers. To break it down requires a lot of chewing, which is why horses developed such long faces to accommodate large, strong chewing muscles. They also have extremely long teeth with extra thick enamel to take care of the tough cellulose walls and any grit that is scooped up with the grass. A horse will thrive on grasses that would reduce a cow to starvation.

  Primitive horses also developed muscular necks and bodies with deep chests and brawny haunches. These animals were designed to flee predators at speed and travel great distances over arid areas to find enough food. These were the very same adaptations that served zebras well as they evolved on the African savannas. While wildebeests and other large grazers eat mainly the leaves of grass, zebras are happy with just the stems.

  Zebras have been recorded eating 50 species of grasses but they prefer just a few kinds, most notably panic grass, red oat grass, buffalo and love grasses. These they digest much more quickly than any other grazing ungulates and, unlike cows or buffaloes, can run just as far and fast on an empty stomach as on a full one while the other ungulates have to rest after eating.

  There are also around eight types of herbs that have been identified as zebra muti. Some references insist they eat herbs by accident, but if you’ve ever fed a horse by hand you will have felt those large, rubbery, prehensile lips picking at whatever you offer with an almost disdainful fastidiousness. They seldom eat anything by accident. When grass is scarce they will eat wild legumes if they can find any.

  There is an African idiom that holds there are no thin zebras. They always seem to be well fattened, even in times of the worst droughts such as the one that gripped the Limpopo Valley while Zulu was running free. The reality has little to do with the fat of the land and more to do with why zebras, and horses, always seem to be farting.

  It’s one of the side effects of having a three-stage fermentation digestive system with stomachs containing billions of intestinal microbes. The job of the microbes is to break down tough cellulose and in turn they produce a continual supply of gas that bloats the animals’ guts and forces its way out through the exhaust system with every other step they take.

  Zebras and horses do surprisingly well in drought conditions. Eland too, as well as oryx, kudu and steenbuck which are all common in Mashatu. Herbivore species that have large or no home territories can easily pack up and move off in search of better pastures. But others such as bushbuck, waterbuck and impala, with home ranges less than five kilometres square, are the first to go into stress when times get tough.

  Warthogs, too, are terminally reliant on water. And indeed they were dropping, some of them stuck like fossilised creatures in the drying mud of congealing waterholes where they lay trapped, encased in hardened clay cocoons. This was also the time when the zebras of Mashatu started coming into oestrus.

  As the season of rain approached in his third year on the lam, Zulu noticed the urine of one of his females was milky and strongly scented. She was not a high-ranking member of the harem but had reached breeding age and had begun pursing her lips and bearing her teeth at Zulu, indicating she wanted his attention. During all his years as a horse, Zulu had not had much experience with females, having had a similar upbringing to a boy who is sent off to boarding school from grade one and from there straight into the military.

  The previous year when females had come into heat, Zulu had responded instinctively, trying to mate with them before they were ready, which had led to a lot of bedroom skirmishing but no biological success. He had not known that it took around four days from the first hormonal signs until a female became sexually receptive.

  This time the stallion played things more
cautiously, closely following the female in oestrus, continually sniffing, nipping and nuzzling her. She in turn would run off, kicking backwards, which only made Zulu more attentive. Whenever she urinated or defecated Zulu would cover her discharge with his own, masking her scent in order to deter any other stallions that might try to muscle in on his girls.

  As the mare’s hormonal production peaked, Zulu became increasingly assertive, head held high and his tread measured, almost like a clockwork animal. Finally, she gave up running and stood still with her mouth agape. That was all Zulu needed, mounting her with an almost palpable release of tension. For the rest of that day, every few hours, the mare showed him her voluptuous hindquarters and Zulu obliged her.

  Zebras are prolific breeders. While they can foal at any time, the majority of births occur in the first few months of the rainy season, November to January. They live on the very fringes of aridity and so have a built-in mechanism to deal with droughts: if the rains hold off they will naturally abort.

  Other than a few localised showers and general meteorological misfires, for two years running proper rain had held off and now, well into the third rainy season, things were looking bleak. By the time the first mare was ready to deliver, two others came into heat and Zulu duly covered them according to the droit de seigneur of a zebra liege.

  In the first year of the drought the predators had enjoyed a fine time of it, taking the young, the weak and the old. But now, into a third year with scant rainfall, anything that was going to succumb to hard times had already done so. There was no standing water left and Nel’s Vlei was a baked earthenware bowl. The large indents of elephant feet made progress across the ground hazardous for other animals.

  The only water available was in wells dug in the sandy riverbeds by the elephants. But they lorded over their precious resource and only when they moved off to go feeding could the other creatures move in to slake their burning thirsts. For predators, these made perfect kill zones and the bleached bones of kudu, eland, giraffe, even zebra littered the surrounding veld.