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Dangerous reptiles – precautions and avoidance
By Cleve Cheney
< Figure 1: Arboreal snakes include vine or twig snakes (top), green mambas (middle) and boomslang (bottom).
Hunting often takes place in remote areas far away from medical help. You don't want to be bitten by a venomous snake under these conditions – in the case of some snakes, such as neurotoxic cobras and mambas, you may not be able to get to professional medical care in time, making your chances of survival slim. It is wise, therefore, to be on the lookout for snakes and to avoid them as far as possible.
South Africa has 138 snake species. Of these 60 are non-venomous, 43 mildly venomous and 35 extremely venomous. Snake venom is of four types. Neurotoxic venom acts on the nervous system and causes death through respiratory arrest when the respiratory muscles (diaphragm and intercostal muscles) cease to function. Cytotoxic venom destroys tissue – this is referred to as necrosis. Haemotoxic venom interferes with the blood clotting mechanism and causes serious and life-threatening internal haemorrhaging (bleeding), and cardiotoxic venom ultimately results in heart failure.
Cobras and mambas have neurotoxic venom, the adder group cytotoxic venom, boomslang and vine or twig snake haemotoxic venom and the gaboon adder a mixture of cytotoxic and cardiotoxic venom. Mozambique spitting cobras also have a combination of venoms – in this case of the cytotoxic and neurotoxic variety.
There is a difference between snakebite and envenomation. A bite by a venomous snake does not necessarily mean that they have injected venom. Snakes have the ability to regulate the amount of venom they inject and a bite can range across the spectrum from a "dry" bite, when no venom is injected, to a full-on bite, when a maximum volume of venom is injected into the victim. Only when venom has been injected do we speak of envenomation.
> Figure 2: Examples of terrestrial snakes: puff adder (top left), rinkhals (top right), snouted cobra (bottom left) and black mamba (bottom right).
The symptoms and effects of being bitten by a venomous snake – even a highly venomous species – may thus vary, according to the volume of venom injected, from almost no effects (a "dry" bite), to severe effects, which in some species can lead to death within as little as 20 minutes (mambas and cobras). The effects of venom also depend on the venom to victim body mass ratio. Young children will normally have more venom per unit of body mass as opposed to adults and will therefore show more serious effects resulting from envenomation. Old folk and sick people also react more vigorously to envenomation when compared to a healthy adult.
< Figure 3: Terrestrial snakes will often retreat to underground burrows left), and love to shelter under rocks and logs (right).
A question often asked is, "How long will a person take to die after being bitten by a venomous snake?" This is a difficult question to answer because again it will depend on the quantity of venom injected, the type of venom, the site of the bite and the particulars of the victim (young/old/healthy/sick/body mass, etc). As a rough guideline and assuming a significant quantity of venom injected into a part of the body that has a good blood supply one can work on the following time frames in terms of having to get a patient to expert medical care:
> Figure 4: Puff adders when stood on in game paths account for most snakebites in South Africa (top). Many bites occur when people collect and pick up firewood or rocks (bottom).
- Envenomation by mambas (black or green) or cobras – 20 to 90 minutes.
- Puff adder and other species of the adder group – within hours.
- Boomslang and vine (twig) snakes – within hours.
- Although boomslang are shy and not aggressive, and bites from this species uncommon, their venom is considered to be the most toxic. However, the venom works relatively slowly and there is ample time to get a person to a hospital. There should be a minimum of delay, however. Treatment in a hospital consists of injections of vitamin K, blood transfusions and a specific antidote which is only issued on confirmation of envenomation by this species.
- Cobra venom is considered more potent than mamba venom but the effects of mamba envenomation are generally more severe because larger quantities are injected.
- The bites of non-venomous species such as mole snakes, house snakes and pythons, for example, should also be treated by qualified medical personnel as serious infection and tetanus is always a possibility. Large pythons can inflict serious bites and can be dangerous as large specimens are quite capable of killing a human by constriction.
- Crocodiles are capable of causing serious injury or death and kill many people in Africa each year. Large "leguaans" (monitors) can inflict painful bites.
< Figure 5: One of the signs that will indicate the possible presence of snakes is shed skin (top left and right and bottom right). When shedding the eye has a layer of opaque skin covering it and the snake is effectively blind until this skin is shed. Being "blind" makes the snake very nervous and it will readily strike out if it feels threatened.
With this as a background let us now look at how a hunter can avoid dangerous reptiles. The old adage of "prevention is better than cure" is most appropriate in this context.
Know where they are likely to be found
> Figure 6: Snakes will leave tracks on suitable substrates. You will often find them across bush tracks and game paths or in open sandy spots where snakes will sun themselves.
Different species of snakes prefer different habitats. Arboreal snakes such as boomslang, green mambas and twig snakes will more often than not be found in trees (figure 1). Terrestrial snakes prefer the ground and can be found on footpaths, under rocks and logs, and anywhere in the veld. They will also retreat to underground burrows to hibernate or to lay eggs (figures 2 and 3). Venomous snakes in this group will include black mambas, cobras and puff adders. Most bites in South Africa can be attributed to puff adders that like to bask in game and foot paths and are often stood on. Bites often occur when people collect firewood or pick up rocks (figure 4). Rock monitors can be found in similar habitats to terrestrial snakes, but may also be found in trees as well.
Snakes are frequently found in garages and storerooms – especially where stock feed or food is kept which will attract mice and rats. The latter in turn attract the snakes, which feed on them.
Some snakes prefer a water habitat and this of course is where we can also expect to find crocodiles and water monitors.
Bow-hunting hides which provide warmth and shelter may also provide a suitable place for snakes to stay.
Know their sign
< Figure 7: Black mamba scat (left) and crocodile scat (right).
In snakes and monitors this may include shed skin (figure 5) or tracks on suitable substrate (figure 6). Snake and crocodile scat can warn you of the presence of these creatures (figure 7). They may also puff and hiss as a warning when they feel threatened. Crocodile leave drag marks on sandbanks and excavations where they make nests for eggs (figure 8). Be on the lookout for these signs as you will be forewarned of the presence of dangerous reptiles and can be on your guard.
Know how to identify them
> Figure 8: Crocodile sign – tail drag marks, tracks and nest excavations.
Learn to identify snakes in the area you are going to hunt. Study their habits, where they are likely to be found and whether they are venomous or not. Such knowledge places you at a distinct advantage.
Know how they are likely to react
When a snake feels threatened it is most likely to respond by trying to get away. If you block its avenue of escape, it may hiss or puff to warn you and may raise its head off the ground. In the case of cobras the hood may be inflated to make the snake look bigger in its attempt to intimidate, it may strike out and hit you with its head without biting, it may actually bite but inject no venom (a dry bite) or if it feels threatened enough may bite and inject venom.
When are reptiles aggressive
Reptiles are aggressive when they are hunting and are attempting to catch prey. Because humans are too big a prey for most snakes they will generally not attempt to bite because they do not regard us as prey. This, however, is different in the case of crocodiles, which are notorious man killers and most definitely regard humans as potential prey (figure 9).
Snakes are aggressive when they feel threatened. Most snakebites occur when people are attempting to play with, work with, catch or kill snakes and the snake fears for its life (figure 10). If you disturb snakes intentionally or otherwise they are far more likely to bite.
Some species such as black mambas can be aggressive when mating or when guarding a nest. Snakes are often very nervous when sloughing (shedding their skin) because a thin layer of skin is also shed from the eyes and the eyes are opaque during this time. The snake is effectively blind and will strike out at anything that comes close to it (figure 5).
Precautions to take
• Keep a lookout for snake sign which will forewarn you of their presence.
• Listen for warning hisses or puffing.
• Be very careful when entering storerooms where food is stored. Exercise vigilance when picking up or moving boxes, sacks, drums or containers in store rooms/garages /workshops as snakes frequently shelter in or under these objects. Snakes will also enter these rooms to shelter or hibernate when it gets cold.
• Be very careful when picking up firewood or rocks – snakes often shelter under them.
• Step onto logs or rocks not over them. Snakes sheltering under these objects may not be seen – especially on the side opposite to your approach. Stepping over may cause you • to step onto a snake or close enough to elicit an aggressive response.
• Leave snakes alone. It is exceptional for snakes to attack without provocation. If you see a snake in the veld and recognize it as venomous, give it a wide berth. If you approach • too close or wilfully disturb, tease or attempt to catch or kill the snake you increase the chance of being bitten significantly. Never attempt to handle a snake unless you are absolutely sure it is non-venomous, even one that appears dead, as some snakes can play dead (rinkhals and shield-nose cobras for example) – this is referred to as thanatosis.
• Be on your guard at night where there are outside lights. Lights attract insects, which attract frogs, which are a favourite prey of snakes.
• Wear closed shoes and long trousers made of thick material or use gaiters. 80% of all snakebites occur below the knee.
• Be vigilant and keep your eyes and ears open when walking along footpaths or game paths as this is one of the favourite haunts of puff adders.
• Check bow-hunting hides carefully for snakes before entering them.
• Check bedding and especially sleeping bags before climbing into them.
• Don't approach too close to the edge of water where crocodiles may be present.
• Don't attempt to cross, walk or wade through rivers or water bodies where crocodiles may be present.
How to react if confronted by a dangerous/venomous reptile
If you encounter a snake heading towards you but still way out of striking range and there is enough time, move out of its way. Preventing it from trying to get away or blocking its path may illicit an aggressive response.
> Figure 9: Crocodiles are notorious man killers. Be on your guard when close to water.
If you find yourself close enough to be within striking range of a snake stand absolutely still. Movement at this stage may cause it to strike. It is very difficult to steel oneself to not move as one's natural inclination is to want to get away but in a situation like this standing absolutely still is the better option. Snake vision is reasonably good at close range but poor at longer distances.
>> Figure 10: Most people are bitten by snakes when they are interfered with in some way and feel threatened.
About the Author
Cleve Cheney, hunting and environmental editor of Africa’s Bowhunter is a very well known figure in bow hunting and in conservation circles in South Africa. Cleve Cheney has been in conservation for 27 years, of which 20 years were spent with the National Parks Board – most of it in the Kruger National Park. During the time spent in the Kruger National Park Cleve culled no less than 50 elephants with a rifle and he has hunted most African game during culling operations.
Cleve has also been an avid bow hunter for 22 years and he has an extensive technical knowledge on bows, arrows and broadheads. Cleve is also an accomplished bowyer and has built many recurves over the years. He began offering bowhunting education courses more than 15 years ago. Until recently, Cleve was a lecturer at the South African Wildlife College where was a lecturer and instructor. He has a diploma in Nature Conservations and a MA degree in animal Physiology. Over the years Cleve has written more than a hundred articles on tracking, hunting, survival skills, and bow and rifle hunting. He started an 18 month long professional hunters course at the SA Wildlife College where he trained the first group of professional hunters.
Cleve has trained many bow hunters and his educative articles on how to hunt African game, as well as many other articles on different aspects of archery bow hunting an bush skills has been published in Africa’s Bowhunter, Game and Hunt magazine, Universal Hunter and many other magazines. He has been the lead article writer for Africa’s Bowhunter for more than 14 years.
His book on tracking, The Comprehensive Guide to Tracking: In-depth information on how to track animals and humans alike, is probably the most in-depth study on this subject available. For those who want to learn more than the basics, this book is a treasure trove of tracking information, insights, methods, and knowledge. The book is divided into logical sections: teaching yourself to track; understanding wildlife behavior; identification of tracks and signs; gait patterns and pressure release; blood trailing; tracking specific animals; track, stalk, and approach; bird, reptile, and invertebrate sign; man tracking; and dangers in the bush.