By Paul Donovan
If you like your reptiles big, they don’t come much bigger than the Nile Crocodile, Crocodylus niloticus. This behemoth of a reptile is one of the 24 representatives of the order Crocodilia, and gives us a tantalising glimpse into what their long gone prehistoric ancestors were like.
Of course ‘modern day’ crocodilians pale in insignificance when compared to their prehistoric ancestors. One can only imagine ambling down to the river during the cretaceous era (Not as though the forebears of humans were around then), to see a crocodile called Sarcosuchus imperator lounging on the banks. That would certainly have been an impressive sight, given this is the largest crocodilian to have ever basked in the earth’s sun at 40ft, and tipping the scales at 17,500lbs. Its nearest living relative is the Saltwater Crocodile Crocodylus porosus.
Elite Amongst the Elite
With 200 million years of evolution beneath their bony scales (65 million of which resembled as they do today) and with the ability to learn, crocodilians are the animal kingdom’s equivalent of the Army Special Forces. With their aptitude to watch the habits of a potential victim without being spotted, creep up on it with silent stealth, and then unleash an amazing amount of power as it ambushes its quarry, often launching half its body from the water, it is a sight you will never forget. These giants of the reptilian world are true apex predators in anyones’ book.
In Botswana, the local name for the Nile crocodile is ‘Kwena’ whose origins refer to its teeth, of which a Nile croc has between 60 and 68. There are two types of teeth, those at the front of the mouth are large and conical and used for grasping prey and tearing flesh, while those of the rear five rows, or so, are smaller and used for crushing bone – which a crocodile has no trouble doing. They are capable of snapping the thigh bone of a large ungulate in half as if it were a twig. And when you hear that crunching sound, it makes you thank yourself that it’s not your leg!
Although I have worked with Niles in several zoological collections in the UK, I never really appreciated them as much as I do now; I think that goes for most reptiles, actually. To see and have the opportunity to work with individuals in a more natural environment, gives you a totally different perspective on their biology and natural history. There is something about keeping them in captivity which takes away part of their persona.
With an average length of between 4 and 5m, and tipping the scales at 400kg, the Nile Crocodile is by far the largest reptile on the African continent. Reports of 6m giants weighing 900 kgs are not unheard of, although many of the true giants have long been poached for their skins, so encounters with such colossal individuals is less of an occurrence nowadays.
Ability to learn
Reptiles are often perceived as not being the most intelligent of animals, but crocodilians are an exception to this rule. Perhaps it has something to do with the fact that they are more closely related to birds than snakes and lizards (they split from other evolving reptiles around the Triassic era some 200 million years ago) and as well as having a 4-chambered heart in common with birds, they also have quite a well-developed brain, albeit a small one.
I remember the very first zoo I worked in over 40 years ago, where I looked after two small Nile croc’s measuring about a metre in length. They were new arrivals, like me, and over a period of time we built up a ‘trust’. I could go into their enclosure to clean it while being in close proximity to them. They would even allow me to lift their tails to sweep beneath them without flying around the enclosure like some demented beast. This was totally the opposite to when I was off, and my superior had to do the cleaning; he said they were totally “scatty”.
When I moved to Botswana, 15 years back, I had the chance to work with a big individual; when I say ‘big’, I mean in the region of 3m. It lived in a rather neglected enclosure, and was thrown the occasional scrawny (feather-less) dead chicken: several of which I found rotting in the water. It was not in the best of health. It was emaciated, and its teeth showed signs of inadequate calcium intake – they had a glazed appearance about them.
A change of diet, therefore, was called for, so I bought a load of Tilapia from the local fishermen. To show you how ignorant the people looking after him were, when I came back with the fish, they asked me “should we de-head and bone them for you?” They also informed me that they were the ones who “plucked the chickens before feeding them to the croc”. When I asked “why” they had a rather bemused look on their faces. What shamed them even more, the crocodile was being housed inside a nature reserve (whose name I will withhold as it’s a shocking place), and the people looking after him were so-called wildlife rehabilitators’ with years of experience!…Still they had a lot to learn about crocodiles.
These wildlife rehabilitators informed me that the croc was a reluctant feeder and only ate 3 or four chickens a year… No wonder he was thin. But then, when just lobbing its food into the stinking pond it was living in, was it any wonder!? My task now was how do I get this reluctant, emaciated crocodile to feed?
Just throwing the fish in, they would end up floating on the surface and rotting like the chickens; not only a waste of time, but also money. What I needed to try and do was bring out its hunting instinct again. Over the course of several patient weeks, by splashing the water at the edge of the pool with a stick, I ‘trained’ the croc to associate this with food. Every time he responded to this by coming over, I gave him a fish.
In the space of twelve months, this poor undernourished, neglected crocodile transformed into an impressive animal. If the croc was near the surface or basking on the bank, and I shouted its name (I called him Charlie), it would also respond by diving back into the water and coming to the edge of the bank ready to be fed. Something else I began to appreciate was just what sort of bite they have. When you are close to a big individual, and it snaps its jaws closed, I can tell you, the hairs on the back of your neck stand to attention.
Just how much power in this bite was shown when one of the celebs from the Hungarian reality TV show I was involved in some years back, was told to “shove this bite meter in that crocodile’s mouth!” We attached the meter to a length of rope. The first attempt failed: the croc grabbed the rope pulling the three people holding it along the ground towards the water’s edge before they had the common sense to let it go. With shaking hands they threw it a second time. Success, the croc grabbed it. When we managed to retrieve it, my 3m croc unleashed a biting force of 1,702 pounds per square inch! A large individual could easily double that, which equates to something like, laying on the floor with a crane crushing your chest.
Crocs and Humans
It is hard to put a figure on it, but some of the more reputable studies into crocodile attacks in Africa suggest that the Nile Crocodile kills several hundred people a year. One crocodile researcher I spoke to some years back, said this figure could actually be as high as 1000 people. This is significantly higher than any other crocodile species (including the infamous Saltwater crocodile, Crocodylus porosus). One of the reasons for this is that Nile croc’s and humans live in close proximity to one another. Fishermen regularly fall victim, as do local farmers.
Of course, many thousands of tourists travel to Africa each year in search of adventure and once in a lifetime holidays, and a number of these also fall victim. One of the popular excursions is to take a leisurely Mokoro (dugout canoe) trip down a waterway as a way of getting really close to nature. But these tranquil rivers are not all they seem. These shallow, unstable floating canoes carved out tree trunks (although many are made out of fibreglass nowadays) often get tipped over by hippo’s; and if getting attacked by a hippo weren’t enough, you may have to contend with the crocodiles.
Several years ago, I lived in Maun, often regarded as the gateway to the Okavango Delta. While there, the local paper carried a story of a rogue hippo capsizing a Mokoro with two German tourists in it. The husband managed to swim to the bank unscathed. Sadly, a croc grabbed hold of his wife’s leg, and took the lower half off. Personally, you wouldn’t get me in one of those Mokoros for love or money now!
An interesting piece of research that has come out from those studying Nile crocodile attacks, is that most attacks can be attributed to individuals of 3m plus in length. This is probably at the point where they change their diet from predominantly fish based, to a more ‘meat’ based intake. And of course, they do not differentiate between a tasty Zebra having a drink at the water’s edge, any more than they do a fisherman casting his net, or a lady doing her washing. A three metre Nile croc, is capable of overpowering just about any animal that offers itself unwittingly as a target.
In Case of Emergency…
There are two accepted ways of escaping the bite of a crocodile, should you inadvertently find one attached to one of your extremities. Fortunately, I have never had to practice either. The first is to poke it in the eye. The second, is a bit more extreme, and involves “sticking your arm as far down the crocodile’s throat as possible”. This opens the flap of skin at the rear of the throat that forms a valve closing off the windpipe, thus preventing the croc from drowning while it’s ripping chunks of flesh off a carcass, or holding its quarry beneath the water to drown it. As soon as it feels water entering the lungs, it will release its grip on you.
Sometimes I wonder just who comes up with these ‘how to get yourself out of the worst case scenarios’. Have they actually tried them, or are they just built on theory? It’s like being told to “stand still and casually step to one side when you can see the whites of a charging rhino’s eyes”. Yea right! I was charged by a rhino once, and trust me, I was behind the nearest tree long before it ever got that close.
An attack by a croc is a frenzied, terrifying experience unlike that of any other animal. You not only have to contend with being incapacitated in a vice-like grip, but being drowned at the same time. While this is all going on, you then, according to the “free yourself rules”, now have to thrust a good arm down the croc’s throat. Although it defies logic, sometimes the illogical can work. I suppose, in times of desperation, you will try just about anything.
On the move
Rain is a fickle thing in some parts of Africa, and during periods when the rains are absent, many of the rivers populated by crocodiles begin to dry up. While many individuals may remain, in the hope that the rains arrive soon, the vast majority leave and go in search of greener pastures; or perhaps that should be wetter ones?
Niles have been known to travel several kilometres across the parched landscape in search of water. The vast majority may succumb to this alien environment, while the lucky few that do find water, can often find themselves in, how shall we say….. unfamiliar surroundings.
Croc’s in the garden
I lived on the outskirts of Gaborone (Botswana’s capital), and the nearest river to us was the Notwane river, a good 15 minute drive away. The river forms an unofficial border between Botswana and South Africa, and in some places is shallow enough to wade across – which illegal immigrants regularly do. The river is home to some nice sized croc’s that can often be seen basking on the river banks. 2013 was a terrible year, as Mother Nature was not kind to us at all; we suffered terribly at the hands of drought, with rivers and reservoirs running almost bone-dry. As the waterways began to dry up, the crocodiles began to embark on journeys to find new places of residence. Some of the smaller of these displaced individuals found their way (rather bewilderingly to some residents) into urban gardens, crossing thick thorny bush, and at least one major road in the process.
I had several call outs to rescue displaced individuals who have found their way into garden ponds or swimming pools. The swimming pool ones I managed to relocate, but the others in the ponds (which are small lakes in some cases maintained by strong boreholes), I usually said to the property owner “why move it, leave it there: not everyone can boast to having a crocodile at the bottom of their garden”. Most of these individuals are only a metre/metre and a half in length, so are unlikely to do any harm to anyone, other than perhaps take the occasional dog. Thankfully, I was never called out to deal with one of the real big boys, so am not sure where they went, although I suspect they may have excavated tunnels in the embankments somewhere along the rivers length to aestivate during the oppressive heat and drought.
In some areas of their distribution, individuals have been known to dig tunnels up to 6m (20′) deep where they then sit out adverse weather in much more favourable conditions. Such periods of enforced dormancy may extend for several months.
Large gape
As well as having a powerful bite, the Nile crocodile also has a pretty wide gape. As it’s about to ambush its quarry, an adult Nile crocodile can open its mouth almost a metre to accommodate even the largest aspect of an animal’s body. The power of the bite, and the gape of the jaws, coupled with their immense strength, will enable a large crocodile to overpower an adult buffalo.
Did you know
During January 2013, a crocodile farm on the Limpopo River bordering South Africa and Botswana was flooded during heavy rains. 15,000 crocodiles escaped, half of which were never recaptured….
Brought to you by Reptiles Express
