Staying alive: the art of stealth and the role of colours and patterns in the lives of snakes
Text and photographs Pat McKrill
The value of colour in nature
Apart from having the ability to post a photo-shopped reincarnation of ourselves on FB, magically transforming a wrinkly 55 year-old human wreck into a wrinkle-free 30 year old Adonis, when it comes to deception, humans have got a long way to go before catching up with the animal kingdom. Apart from going red with embarrassment, or by holding your breath for 5 minutes, what’s your best attempt at changing colour without the aid of pots of make-up?
Boing! Sorry, next contestant please.
Sit down and watch a NatGeo clip showing a squid changing colour and disappearing, right before your eyes, without moving. Now that’s magic!
Just about every plant and creature in our wonderful natural world, relies to a greater extent upon the colour and/or shape of itself, to impact on its life and that of others. Colour, and not necessarily the bright and loud variety, can make something attractive to one, repulsive to another, it can make the wearer feel better about itself, and for many, it can most certainly help them to survive another day when used in the form of camouflage.
Mother of Pearl butterflies are master blenders.
Most colourful plants flaunt their beauty in order to attract the insects and birds that will help them to distribute their pollen, that which initiates the development of the seeds that will similarly be distributed, to germinate and provide more colourful plants – a fine example of symbiosis, with a touch of colour. Colours are sometimes critical in many a creature’s world, to a lesser extent perhaps, where the long-term relationships of some species might not necessarily suffer irreparably if the respective mates were not exactly oil paintings – those birds for example, who are not spectacularly coloured, such as the Spotted Thick Knee (Dikkop).
Long-term partners having a tiff. These Spotted Thick Knees (Dikkops) are a great example of how bland colouring can be an effective camouflage.
In the short-term relationships of many of the more competitive species that are less than faithful to last season’s spouse, colour becomes extremely important. Seasonal colour changes in nature have specific reasons – not always fashion related – but for some reason, snakes number amongst those that don’t get a look in when the new season’s colours are being dished out.
50 shades of grey
There will always be exceptions to the above. For example, the drably coloured blooms, some of which are predators, that although not appearing to have the same pulling power as the brightly coloured ones, can in fact do so pheromonally, drawing unsuspecting insects to their cunningly attractive but deadly table.
Snakes are not as colour-enhanced as many of the other things on this earth, and being mobile, they also can’t really use other means to attract their food to them as can the drab but deadly predatorial plants mentioned above. Snakes are a feared form of biological control, whose job requires them to remain as unobtrusive as possible, despite them having to get close to their prey in order to kill it, so if the odd blotch or stripe on a drab background helps to achieve that end, bring it on.
Puff adder in its comfort zone.
What follows is my take on how the snake, an extremely important balance element in nature, has had to adapt in a very different way altogether.
Maximum utilisation of available resources
All snakes are predators. With few exceptions, their prey is a moving target, meaning they have to hunt it and kill it using the art of deception to carry out their mission. The deception part is vital, in that the bulk of snakes prey upon animals that can move faster than they can, by flying, swimming or running away – except of course the slugs and snails upon which the well-known slug eater (Duberria lutrix) feeds. As I said, there’s an exception to every rule!
Python (Python natalensis), puff adders (Bitis arietans), vine snakes (Thelotornis capensis) and many other species are ambush-feeders which are dependent upon stealth and camouflage to hunt their prey from within its home territory. They locate the source, hide, and then wait for the food trolley to come to them.
A 3 metre python that the buck won’t see. A perfect example of how neutral colours and broken patterns can help an animal to hide.
A Puff adder in defensive mode. Few people or animals would notice this.
Snakes do not seem to rate colour as highly as do most other creatures and plants, and the closest a snake comes to changing colour might be when it sloughs the old skin and re-emerges in a bright new coat of shiny scales. Their primary focus is on getting through another day without being killed, and when it comes to procreation amongst snakes, it’s the girls who do the calling – pheromonally – when they’re ready. Snakes are solitary creatures, and a female in oestrus, would broadcast an almost secret pheromonal signal via the airwaves and on the ground, designed to attract male suitors of the same species. No fancy outfits or gaudy colours necessary there. Once the males have got the message – via their Jacobson’s organ* – they home in on the target, sometimes arriving in numbers from the surrounding terrain, to engage in a sort of arm-wrestling contest with other males to determine the winner, and the losers will have to come back next season. Again, no colour required there.
*A vomeronasal organ located in the roof of the mouth, helping them to gain important information in terms of their surrounds, food source, danger (predators, fire etc.) as well as the location of like species in the mating season.
When it comes to procuring their next meal, in addition to smell, snakes use their eyesight which ranges from good for the arboreal species, to poor for the tunnel dwellers, along with their highly developed ability to sense pressure variances and vibrations precipitated by proximal movement.
One only has to sit and watch a snake, slowly making its way along the top of the garden wall or crossing the open veld, oblivious of your presence, (yes, you can do this folks – without being killed – try it one day, you’ll be gobsmacked) and we can see the constant flicking in and out, of the forked tongue, downloading information as it goes. Whilst looking for food however, those whose trade is foraging above the ground – often in the open – the night adders, cobras, sand snakes, mambas etc. – will be exposed to predation by all manner of animals above ground, unless that is, they can blend in with their ever-changing surroundings.
Short snouted sand snake, head up, stalking lizards. The colour blend, irregular body shape and the patterning all helps the cause.
Although utilising their neutral colouration to camouflage themselves, with the exception of the Horned adder (Bitis caudalis), believed to use its dark-tipped tail as a lure for desert lizards, and the vine snakes, assumed to use their brightly coloured tongues as lures, as far as herpetologists can determine, snakes don’t generally display any colour that would suggest a need to attract other creatures – subtle regional colour differences excepted, their colours are relatively neutral. They’re certainly sensitive to movement, and waving a red flag at a snake, would elicit the same reaction from the snake as would waving a green flag – instant reaction to the movement – not the colour.
Whilst living in Mount Edgecombe, I was fortunate to be able to conduct an unplanned experiment with a green laser light. My intention in shining the light on the face brick wall next to our verandah, was to pinpoint for an interested observer, the presence of about 6 variegated/spotted bush snakes (Philothamnus semivariegatus) which had congregated over a relatively small area.
Spotted or variegated Bush snake wearing its gecko-hunting outfit.
I achieved my primary objective and more, because it also enabled me to study the responses of the snakes to light movement as opposed to body movement. The snakes – all males – had responded to a pheromonal signal emanating from a female hidden somewhere in the gutter area, and, as I’m sure some of you will understand, they were fairly keyed up. Some of them showed an immediate interest and darted towards the moving light which I assume they determined to be an interesting, possibly edible item. Not wishing to divert their primary focus, I turned off the light.
Since that experience, I have used different laser light colours, green, red and ultra violet to the same end, illustrating that once a snake becomes aware of unusual or unexpected movement, it will react accordingly, using the additional information provided by its other senses, to determine its next move. As predators, they are opportunists, and every movement has potential. Object unknown – investigate. Enemy – flee. Food item – hunt. Colour – who cares?
Advertising is for exhibitionists
I have to explain at this point, why I say that colour doesn’t play a significant part in the ‘advertising’ department in a snake’s life. Those who read my previous article on ‘what eats snakes’, will understand the creatures’ need to remain unobtrusive.
Puff adder exposed and looking for a place to hide.
Therefore it makes sense, that unless it’s elevated, a snake whose eyes are a mere few millimetres above the ground, will see little else apart from that which is in close proximity. Therefore it’s unlikely that a brightly coloured snake – or anything else for that matter – will catch their eye. Worldwide, in the natural habitat, there are very few brightly coloured snakes (I exclude those captive bred specimens which have been doctored genetically by breeders, to enhance colour features for the pet trade).
The few with brighter colours that we do have in the Highway area – some of the smaller and less venomous terrestrial species such as the garter (Elapsoidea) or harlequin (Homoroselaps) snakes – might be uncharacteristic and a wild guess suggests that these might have their relatively bright colours to ward off predators above ground* – an occasional habitat for them – but I can’t really think that it’s a primary requirement when it spends the bulk of its life in the unlit underworld, where any predator would need a good nose and a torch to find it.
*Common in the insect world and referred to as aposematic colouration, this is a colour combination – usually a mix of two or more colours, black, white, yellow, orange or red – that advertises danger to those who dare come near or try to eat you.
Aposematic colouring on these caterpillars helps them to avoid predation.
No matter which version you believe, of the origin of our world and its inhabitants, it’s a fair guess to say that most animals and plants got here long before us. Based on this assumption, I am in agreement with those who feel that any adaptations that have taken place over the millennia to all manner of flora and fauna since they arrived, have taken place for a purpose. In the snake world, it would certainly make sense that if a snake lived above the ground, apart from any fancy little additional stripes and blobs it might have, a base colour in the earthy colour range (black, brown, fawn or olive/grey) would be a sensible one to have – if it wanted to remain unobtrusive. The same would apply to those species – Boomslang (Dispholidus typus), bush snakes, green snakes and vine snakes for example – that live and hunt in the tree-line, where green, brown, or variations thereon might be a sensible choice (not that they have a choice).
Female Boomslang. A perfect colour and body shape camouflage combination.
In both cases, the base colouration is designed to camouflage them by allowing them to blend as much as possible, into the background, in order to avoid detection by their enemies. The addition of patterns would assist in breaking up the body shape.
There are approximately 160 different species of snake in South Africa, many of them are widely distributed, but in the greater scheme of things, no matter how acclimatised they might have become to the ever growing human intrusion and habitat destruction in their world, we must ask ourselves, in our lifetimes, how many have we ever come across by chance in the environment around us? I guess we’d probably say very few indeed, so when it comes to stealth, deception and staying alive, I reckon that’s pretty clever – don’t you?
About the author
Pat was born in the UK, educated and brought up in Rhodesia/Zimbabwe, and came to South Africa in 1983. He developed an early interest in the study of the behavioural aspects of insects and animals, rather than the deeper scientific side, and he’s worked with snakes for most of his life. Pat conducts educational walks and talks throughout SA and into neighbouring countries where snakes are grossly misunderstood and needlessly killed. He writes articles for a number of publications, and has written the book ‘Getting to Know the Neighbours’, which is all about understanding snake behaviour and is aimed at teaching others how to come to terms with them.