The Travelling Vet

16

CROCODILE

‘An appeaser is one who feeds a crocodile, hoping it will eat him last.’

Winston Churchill

I spluttered and coughed, inhaling the unavoidable haze of the copper-red dry African dust that filled the minibus through the open window. I quickly closed it to minimize the effect. It was 6 a.m. on a cold morning in August, and we had just turned off the main road onto a dirt track that appeared to end in a barren wilderness of South African bush. The only clue that we might vaguely be heading in the direction of habitation was the dilapidated house postbox by the side of the road. My companions in the back of the minibus were abruptly woken as the change in terrain greatly increased noise levels at the same time as dramatically decreasing the comfort of our ride. Each pothole and small boulder caused the whole vehicle to vibrate and judder violently as its suspension was tested to breaking point.

In true African style the dirt track seemed interminable, with visibility being reduced substantially by the distinct dusty haze we were generating. We had already been travelling for an hour and a half when we turned off the main road for our final destination, and that leg was rapidly beginning to seem a mere prelude to our journey as a whole. We had left the comfort of our lodges in pitch darkness heading north-west from Nelspruit on today’s adventure to catch and relocate a 4.6-metre male Nile crocodile weighing in at about 700 kg.

As another beautiful blood-orange African sunrise began to evaporate the low-lying mist, a solitary whitewashed brick building emerged in the distance. As we drew ever closer, other components of the farm hove into view. There were half a dozen buildings, all uniform in shape, single-storey brick sheds with tin-sheeted roofs. Each structure was about 10 metres wide by 20 metres long. From previous visits to other crocodile farms, I knew these to be the enclosures where the hatchlings were kept in batches of several thousand, arranged by age from the egg to two years old. Then there were a dozen similar-sized concrete pits, each containing a dam of water and a basking area, which contained the three-to-five-year-olds, this time in batches by size of a few hundred. The final structure was one large enclosure, about the size of a football pitch, with two dams surrounded by a large, grassy embankment. It was within this enclosure that the breeding males and females were kept, 120 in total, all fully grown specimens, ranging from 3 to nearly 5 metres in length. The boundary to this enclosure was a 1-metre-high concrete wall surmounted by 50 cm of chain-link fence. The two large dams were separated by the feeding gangway, which protruded halfway into the enclosure. This gangway was accessed through a locked gate and was a continuation of the surrounding concrete wall, though without the chain-link fence on top. I imagined the carnage of feeding time as the workers threw meat at the sea of snapping jaws.

The one noticeable element to the adult enclosure was that it was very much designed to keep the crocodiles in, rather than to keep humans out. There was no electric fencing, no double fencing, no reinforced fencing, and no barbed wire; there was no security guard, and only a couple of dilapidated signs reading ‘WARNING! CROCODILES! TRESPASSERS WILL BE EATEN!’ If someone were ever stupid enough to climb over the fencing, then good luck to them – that was the implication. This was not a mass of health and safety regulations like you’d find in Britain, Europe or America. This was Africa: a healthy fear and common sense were safety enough.

From the 1950s to the early 1970s, crocodilians the world over were extensively exploited, predominantly for their skin to fuel the leather industry, leading many species to the brink of extinction, including the African Nile crocodile. In 1975 the Convention on International Trade in Endangered Species (CITES) was enacted to regulate the trade in wild species, and many countries, including South Africa, adopted legislation to protect crocodilians and increase their global numbers.

With demand for crocodile skin and meat still as high as ever, crocodile farming became a way to reduce pressure on the wild population from illegal poaching, while restocking those populations by releasing juvenile crocodiles into the wild. So successful has this proved that many crocodile species have been taken off the endangered list. The initiative has demonstrated how a voracious human desire for animal products can be sustained while also protecting the very species that fuels it. The success of this concept means that it is often cited as a model for protecting other species, such as the rhinoceros. It would be nice to think that demand for such products could be stemmed, but the reality is that once humanity gains a taste for something, it is extremely slow to surrender it, and for many species that are being unsustainably exploited for a product, time is sadly running out.

We disembarked from the minibus, taking a moment to stretch muscles stiffened by the drive. Derik, having driven separately, was already at the boot of his car getting his equipment together when the owner of the farm came to greet us. Piet was a tall, broad-set man in his early fifties, wearing khaki shorts, a checked short-sleeved cotton shirt and a camo baseball cap. Addressing Derik initially in Afrikaans, he then turned to greet us in the warm, welcoming and friendly way to which South Africa had accustomed us. He briefly described his crocodile farm, and the reason for the animal’s relocation, then gratefully explained how necessary it was to have a team of people for this job. The crocodile in question was about fifty years old, and for many years had been the farm’s primary breeding stock, so the owner was keen to bring in a new gene pool and was therefore selling him to another crocodile farm.

The first step in the process would be to lasso a rope around the crocodile’s upper jaw. He would instinctively clamp down on this and start fighting the restraint. This was where our extra manpower was vital, since in a tug-of-war battle, 700 kg of prehistoric cunning would attempt to gain the predatory advantage by taking to the water, where the immense muscle power of his tail could be used to maximum effect. Conversely, our own objective was to keep him on land to maintain our modest advantage and allow Derik the opportunity to sedate him.

Crocodilian anaesthesia is still something of a mystery, since many drugs that work well in mammals, and are effective in other reptiles, are unpredictable or ineffectual in crocodiles. The doses required are often so large it makes them impractical to use. The induction time is at least five times longer than in mammals, but then the drug persists in the circulation for days, and sometimes longer than the reversal agent, which means a crocodile can re-anaesthetize the day after a procedure, a phenomenon known as ‘renarcotization’. So an owner can drain a dam of water on the day of a procedure, then refill it the following morning, only to find his crocodiles have drowned in the afternoon because they have renarcotized.

One class of drugs that does work effectively, and within predictable parameters, are the paralytic agents, the required doses of which are also practical and manageable. However, these drugs are solely muscle relaxants rather than anaesthetic agents, so are not suitable for any procedure that will cause pain, but are ideal for a job limited to an animal’s capture, transport and release. Gallamine was the preferred drug, since it relaxes the skeletal muscles well, but has no effect on the muscles that control breathing, which therefore promised a safe working environment for us without endangering the crocodile’s life. Furthermore, with the animal safely relocated, there would be no need to administer a reversal agent: the drug would wear off naturally after a few hours, and then the crocodile would be fully functional again.

Once injected, it would take about fifteen minutes for the Gallamine to take effect, and then we could claim control of the situation. The immense strength of the crocodile’s masseter (chewing) muscles – giving him 3,700 psi-worth of crushing power through the arcade of his eighty teeth – would be tamed by the Gallamine and then rendered ineffective by tightly taping his jaw closed. The 700 kg of raw, unfathomable muscular power would become nothing more than a limpless weight, and so one of the animal kingdom’s most effective killing machines would be temporarily tamed enough to be securely craned onto a truck, safely transported and subsequently released into his new home. That was the simple plan, anyway, though one, as with all wildlife work, fraught with a plethora of potential dangers.

As we strolled from the parked vehicles, equipped with all we would need for the task, we got our first detailed viewing of the adult enclosure. The dams were a murky brown colour, making it impossible to see what lay beneath, but a few crocodiles were visible just above the surface, though by far the majority of the inhabitants occupied the dusty, grassy bank, basking in the heat of the early morning sun. Stretched in every direction was a sea of the biggest crocodiles I had ever seen in my life, their dun, murky green bodies starkly contrasting against the sandy, rubicund soil on which they lay. Some were poised to enter the water, others were tucked against the concrete boundary wall; some had their mouths wide open, exposing every one of their gleaming white teeth, others had their jaws tightly closed; some faced the water, others the wall. The one thing that united them all was their absolutely motionless form, their glassy green eyes inert. It was easy to imagine that what I was seeing was a collection of statues, and yet, given even the slightest stimulus, their reaction would be lightning swift, and deadly.

It was then that the realization dawned on me that we would be deliberately entering this pen and wrestling with this 700-kg Nile crocodile, in an enclosure containing 119 other adults. To voluntarily put ourselves in such acute danger seemed utter madness, though I knew it was my ignorance of crocodilian behaviour that was elevating the danger factor in my mind. While accidents invariably happen when dealing with such dangerous animals, they are largely caused either by complacency or by ignorance of their behaviour. If we were to enter the enclosure, there was certainly a way to do it safely – but it still required an immense application of mind over matter.

One factor that would contribute to our safety was the chosen time of the capture. ‘Poikilothermic’ or cold-blooded creatures, as all reptiles are, rely on the heat of the sun to warm them up to regulate their metabolism, so any reptile is less active first thing in the morning than at the end of the day. That’s why a dog is more likely to be bitten by a snake on its morning walk than the evening one: in the morning a snake will be slower to move away from an inquisitive approaching dog and thus more likely to strike out in defence than slither off in escape, as it will tend to do later in the day.

A second factor was the day that had been chosen for the relocation. Adult crocodiles will usually only feed once a week, and feeding time for these animals had been the previous day, so they would be relatively sluggish, given the vast amount of energy it takes them to digest their meal – though their reaction time would still beat ours hands down. More significantly, though, they would not be hungry, and so, provided we didn’t interrupt their morning siesta, or accidently step on one, they would be content sunbathing rather than bother to chomp on the nearest passing leg.

This was all very well in theory, but looking across the enclosure, I could see no safe route through the sea of bodies that lined the ground, so someone would have to clear a path by gently encouraging them to move. I had no idea how easy that would be, but it was not a job for which I was going to volunteer.

One of the farm workers met us at the gate to the feeding gangway, unlocking it and ushering us through. Piet led the way, pointing to the bank on the far side of the dam, deep in conversation with Derik. Despite my frustrating ignorance of Afrikaans, it was clear that he was indicating the male crocodile we were there to move. As I focused in on the animal, it was almost as though he grew before my very eyes. While at first glance there seemed to be a uniformity to all the crocodiles in the enclosure, on closer inspection I noticed the wide range of their size and width. Without doubt, though, this boy was the biggest. Lying motionless, at an acute angle, facing away from the dam, jaws wide open, his teeth glinting in the morning sun, it was almost as though he were inviting us to catch him if we dared.

As Derik and Piet continued their conversation, another farm worker passed us by, carrying a 10-foot-long, 2-inch-wide black plastic pipe, then climbed over the gangway wall into the enclosure. He boldly proceeded to thrash the ground in front of any crocodile that lay in his path as he sought to create a safe passage to the crocodile in question from the gangway where we stood. I was convinced his method was a sure-fire way of ending up as an unexpected bonus meal. Remarkably, however, although they were none too happy for their morning basking to be so rudely interrupted – a displeasure they made perfectly clear in a series of wild snaps and hissing noises – they slowly moved away or took to the water. It was a remarkable insight into this man’s knowledge and understanding of crocodilian behaviour. After about ten minutes a path had been cleared, which he then proceeded to patrol.

Meanwhile, Piet was preparing a lasso from a 20-foot piece of industrial strapping, which he lightly fastened to a 6-foot pole. Task completed, he and another worker followed the first over the metre-high wall into the enclosure. Piet took the lead, approaching his quarry from the side. Our crocodile remained completely motionless as he eyed the potential threat. Standing at what seemed an insanely close distance, and well within striking range, Piet stretched out the primitive and clumsy contraption, attempting to lower it over the animal’s upper jaw. The crocodile was not so easily fooled, though, and as soon as he felt the contact of the lasso on his snout, snatched at it, ripping it from Piet’s hands and casting it aside, and then turned to face the water, his jaws almost shut. As if it wasn’t obvious enough that this was not part of the plan, Derik let out an Afrikaans expletive that even I could understand.

The situation was now delicately poised: at any moment the crocodile might take to the water, which would make catching him impossible. If that happened there were only two possible solutions: either to come back another day, or wait the three hours it took to drain the dam. In my experience, African wild-life work was full of wasted days, and a range of Plans B, C, D or Z. It was one of the reasons for the vast costs involved in operations like these. More than any domestic animal, wildlife requires immense patience.

With this particular job, even if we drained the dam, there was still no guarantee of success, since the crocodile might decide to stay where he was. If so, the human risk factor would be infinitely increased, since the algal slime at the bottom of these drained reservoirs would be treacherously slippery. To attempt to go into one in pursuit of an adult crocodile would be suicidal. I remembered a terrible story Cobus had once told me. He had been asked to remove 150 adult crocodiles from a farm by the owner’s wife, after her husband was killed attempting to clean a dam. He’d done the job thousands of times before, but on this occasion he slipped, and fell in, as the dam was draining. By the time the water had gone, so had most of him. Maybe coming back another day was the better option …

Fortunately, having repositioned himself, the crocodile now settled, apparently quite content to stay on the bank, showing no interest in the water. We still needed to wait for him to reopen his mouth, though, to allow Piet another attempt at lassoing his upper jaw. Giving the crocodile a chance to settle, and after reconstructing the lasso, Piet stepped back to watch him at a distance of a few metres.

It was probably ten minutes before the crocodile relaxed enough to slowly open his jaw. Piet allowed him another few minutes before slowly approaching his head for the second time. This time starting with the loop well in front of the snout, he ensured he was lined up with the upper jaw, and then in a quick movement brought the lasso into and over the animal’s mouth. The crocodile did the rest, snapping his jaw tightly shut and whipping his head and neck away from Piet in a movement that elicited all this creature’s trademark force. And that movement was exactly what was required to cause the loop of strap to tighten around his upper jaw: 4.6 metres and 700 kg of prehistoric muscle power was now caught. And he knew it.

The jaw-snap and neck-jerk was just the start of the unleashing of his fury at this unwelcome restraint. He started thrashing from side to side, deploying the immense power of his tail to create a full body movement. Backwards and forwards, side to side he went; the speed and strength with which he continued was terrifying to watch, and it was all Piet could do to hold on. The two farm workers were quick to lend added manpower, but the three of them were still no match for this creature who now, clearly dissatisfied with the progress he was making, decided to take the fight to his preferred hunting ground, and dashed into the water.

That immense, formidable tail, which had been such a powerful lever on the ground, now instantly became a colossal rudder that allowed him to repeatedly barrel-roll, snapping and thrashing as he went, with such massive force it was a wonder the strap held. The dam of water, serene and motionless just moments before, was now a violent, churning, chaotic storm. The crocodile’s power on land was exponentially increased in the water, so the task of maintaining any element of control over him was now utterly impossible.

With every roll, whip and thrash from the crocodile, the three men precariously holding on to the lasso, were dragged ever closer to the water’s edge, and in a flash the situation could have become extremely dangerous: the slightest loss of concentration, the slightest slip, and Piet and the others would be plunged into those primal waters. This was the critical moment we had been briefed about earlier, and before we could even register a conscious thought or verbalize the action required, we all responded instinctively and in unison, momentarily oblivious to the 119 other dangers within the enclosure. Scaling the metre-high wall, we sprinted to join the tug-of-war, grabbing on to a section of strapping that lay on the ground behind the three men. Three became four – five – six – but the still the crocodile dominated the contest. Seven – then eight – then nine – and finally, with ten bodies pulling against the crocodile, we were able to stabilize and hold fast against him. Like playing a fish on the end of a line, it was now a case of letting him tire himself out, so he could eventually be pulled back out of the water.

The storm he generated in the water made it impossible to see him, but the relentless pull on the taut strap left us in no doubt as to his power. As seconds turned into minutes, it seemed like an eternity, and still he showed no signs of fatigue. The thought occurred to me that maybe we would tire first; how would that play out? I tried to shake the image out of my head.

After what must have been twenty minutes of us holding fast, heels dug into the grassy bank, sweat dripping from every brow, and fingers numb from holding the strap so tightly, we got our first sense of his ebbing strength as we felt a shift of momentum away from, rather than towards the dam. Over the course of a further few minutes, step by step, little by little, inch by inch, we found ourselves retreating from the dam edge, gradually pulling our enormous catch onto the shore.

Once landed, he seemed to have given up the fight entirely, but our job was still far from complete. With the rest of us still holding fast, Derik peeled off to grab his pole syringe and draw up the Gallamine to inject into the crocodile.

One of the characteristics of reptiles is the presence of scales, from the soft, slimy covering of a snake to the hard, bony shell of a tortoise. Crocodiles have a bit of a mixture, with softer tissue on their underside and hard bony plates or ‘scutes’ over their back and flanks. These scutes complicate the procedure of administering an injection, since they are so strong that a needle will simple break off or bend if it makes contact with too much force. It is therefore esssential to insert the needle between these scutes, allowing it to penetrate through this outer layer into the underlying muscle, for the drug to be safely delivered into the body. The best location to do this is at the base of the tail, just where it joins the body, where there is more of a gap between these bony plates, and a larger injection site to aim for. This is also the greatest area of concentrated muscle in the animal’s body, and that is the tissue we want the drug to enter, since muscle has a rich blood supply, and thereby facilitates the speedy absorption of the drug.

Derik returned with the 6-foot pole syringe – a simple light metal pole with a heavy-duty plastic syringe and needle attached, allowing the safe injection of a dangerous animal from a pole-length away. He wasted no time injecting the Gallamine, the crocodile responding with a final, violent thrash of his tail – and then we settled down to wait for the fifteen minutes of the final countdown. The test to ensure the efficacy of the drug was to push down gently on the crocodile’s upper jaw: if it had worked, the crocodile would struggle to reopen his mouth; if it hadn’t … We made sure to give the head end a wide berth.

After ten long minutes, Derik gently touched the crocodile’s nose with a long stick: no response. Then, applying greater force, he tried to push the jaw shut – and in an instant the crocodile responded, snapping up at the stick and crunching it to a pulp. We obviously had longer to wait.

Five minutes later, the same graduated provocation from Derik met no response. Gingerly removing the stick from the top of the nose, he brought it to the front of the snout, gently tapping at the exposed gleaming canines: still nothing. The Gallamine was working, it seemed. A few of us relaxed our hold on the strap to ready ourselves for the final phase. What we needed to do now was loop another lasso around both the top and bottom jaw, which we would then hold fast, and with the jaw tightly secured, Derik would tape the mouth shut with four or five rounds of industrial-strength gaffer tape. Even to approach the jaws of this monster crocodile required immense trust in the science and pharmacology of our profession. It is one thing to read about a drug in a book, to know how it works, what receptors it acts on, and the effect this causes in the body, but – believe me – to put yourself in harm’s way on the basis of that knowledge requires colossal faith the first time you do it. This wasn’t Derik’s first time, and so without a moment’s hesitation, as we held the animal down, he rapidly secured the lasso and applied the tape, circling the jaw multiple times to ensure its total restraint.

Now we were in complete control. Releasing the strap that had taken up our energies for over half an hour, our focus now became the securing of his legs so they wouldn’t get damaged in the move, and then the larger task of lifting him onto a stretcher. The transport vehicle was a truck with a large crane attached. With the crocodile safely secured on the stretcher, we signalled to the truck driver to lower the crane, and within moments 700 kg of Nile crocodile were being hoisted through the air and lowered onto the truck. With the animal safely contained, the driver set off on the two-hour journey to his new home, and, after bidding Piet and his team farewell, we followed him on his way in our minibus.

We successfully and very easily offloaded him at his destination, the Gallamine still flooding his system to give the necessary muscular relaxation to allow us to work safely. It would be another few hours before the effects wore off, and then it would be time for him to explore his new environment. As we drove away, I felt it would take far longer for me to process the amazing experience I had gone through that day. It was another successful job well done, but I felt completely wrung out, both physically and emotionally. I had definitely stepped out of my comfort zone with this one. I had certainly learnt a lot about crocodiles’ behaviour, and how to interact with them, but I tried not to think about the range of possible disasters that had all been averted – rather too narrowly, I couldn’t help but think.

I still can’t quite decide if the day had gone so well because of luck or skill.

Crocodiles: fast facts

Crocodylus niloticus: The Nile crocodile

Distribution: Widespread throughout sub-Saharan Africa.

Names: A male is called a ‘bull’, a female a ‘cow’, and the young a ‘hatchling’. A group of crocodiles is called a ‘float’.

Life span: 70–100 years.

Habitat: It is the largest freshwater predator in Africa, inhabiting freshwater lakes, rivers, freshwater swamps, coastal estuaries and mangrove swamps.

Diet: Their staple diet is fish, but they will scavenge carrion and as ambush predators will attack anything unfortunate enough to cross their path, including wildebeest crossing the Mara river during their ‘great migration’. Adults can survive a year without eating.

Incubation: 90 days, laying 25–80 eggs over a 2-month period.

Weight: About 11 inches long, weighing about 70 grams, on hatching, reaching 2–5 metres and weighing anything from 220 and 700 kg as adults.

Growth: Hatchlings grow to about 1.2 metres by 2 years, when they naturally leave the nest. By 4 years they are about 2 metres long and at this size they are much less susceptible to predation or cannibalization. They reach sexual maturity at 12–16 years, depending on their health, size and weight, and will continue to grow through their life.

Body temperature: Like all reptiles, crocodiles are ‘poikilothermic’. Their ideal temperature range for basking, allowing optimum performance in the water, is between 18.8 and 29.2 °C.

Interesting fact: The Nile crocodile has temperature-dependent sex determination: if the average temperature during the middle third of their incubation period falls outside the range 31.7–34.5 °C, their offspring will be female, if within, male.

Conservation: In 1971 all 23 species of crocodilians were considered ‘endangered’ or ‘threatened’, leading to the foundation of the Crocodile Specialist Group (CSG). Crocodile numbers have since undergone the most dramatic improvement in conservation status of any group of vertebrates, with 7 species remaining endangered, 8 no longer considered endangered, and the remainder sufficiently abundant to support well-regulated annual egg harvests. The key to this success is the cooperation of companies involved in every facet of the international reptile skin and leather trade. Today the crocodilian skin industry views conservation as an investment in the future, with many companies contributing to conservation projects and actively curtailing illegal trade. While the work of the CSG has been extraordinary, they continue to strive to bring all crocodile species off the endangered list. See: www.iucncsg.org.