Iguanas: fast facts
Iguana iguana: The green iguana
Distribution: Originally found in Central and Southern America, from Southern Mexico to Central Brazil, the Dominican Republic, Paraguay, Bolivia and the Caribbean.
Names: A male is called a ‘bull’, a female a ‘cow’, and the young a ‘hatching’. A group of iguanas is called a ‘slaughter’.
Life span: 10–12 years.
Habitat: Iguanas are diurnal, arboreal rainforest dwellers, often found near water.
Diet: They are naturally herbivorous, eating leaves and some fruit in the wild; in captivity, kale, turnip, mustard or dandelion greens suffice.
Incubation: 90–120 days, laying anything from 20 to 71 eggs.
Growth: Hatchlings are about 3 inches long, weighing about 90 grams at birth, growing rapidly for the first 3 years when they reach sexual maturity. Growth then drops off dramatically, but they can continue to grow all their life and can reach up to 6 feet in length and weigh 9 kg.
Body temperature: Like all reptiles, green iguanas are ‘poikilothermic’, meaning they can’t regulate their own body temperature. Their temperature gradient in captivity should be 26.6–34.9 °C.
Interesting facts: In the aftermath of Hurricane Luis in 1995, several uprooted trees drifted over 200 miles across the Caribbean from Guadeloupe to Anguilla. These trees were found to be carrying about a dozen green iguanas, which subsequently started to colonize the island. Releases, either deliberate or accidental, from the pet trade have led to their classification as an invasive species in Texas, Florida and Hawaii.
Conservation: They are the most popular reptile pet in the USA despite being quite difficult to properly care for, and vast numbers will die within their first year. Their global population is unknown, but about 800,000 were imported into the USA in 1995. They are not considered an endangered species by the IUCN, but they are listed in the Convention on International Trade in Endangered Species of Wild Flora and Fauna, which recommends control of their trade. The major concern is the diminishing of wild populations to furnish the pet trade, and the massive welfare issues involved in it. Trade in wildlife is the second largest illegal trade in the world after drugs, with an estimated value of $323 billion in global imports of all animals in 2009. TRAFFIC is a global wildlife-trade-monitoring network that works in the context of biodiversity, conservation and sustainable development. See: www.traffic.org.
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 woul
d 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 coul
d 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 Travelling Vet Page 23
