Will climate change change lives? Ask a snake.


Text Pat McKrill Photographs Pat McKrill, Charles Botha, Nick Evans, Marius du Plessis

Guesswork or reality?

It’s hard to ignore the noise and evidence associated with the subject of climate change. Leonie Joubert (Scorched) on a visit to Marion Island in 2003, talks of the island “being squeezed like a sponge by the fist of global warming”. Al Gore took some flak some time back with his movie about climate change, Inconvenient Truth, but judging by what we can now see, it’s possible that they were pretty much on track. There’s also a school of thought that says it’s going to get colder, and each has presented enough credible statistical evidence to prove its case, bringing to mind the saying attributed to Benjamin Disraeli, which goes something like “there are lies, there are damned lies, and then there are statistics”.

Not that anyone is necessarily lying, but either way, like Nostradamus, proponents will ultimately say, “we knew that would happen”. Back in the late 60s, a work colleague sold his home and moved his family of 4 into rented premises, telling workmates that the end of the world was nigh. He based this on a religious belief, but the difference now is that serious life-altering changes are indeed happening and becoming far more obvious.

Water, water everywhere, but…perhaps not

Consider the common resource that many of us take for granted; potable water. Since man stood upright, he’s been engineering the availability of water to suit his needs, for example, damming up water courses and draining wetlands. In doing so, he has often forced other creatures and plants on the planet to adapt accordingly. Besides utilising that which has been available to them via rainfall, rivers and natural catchments, reptiles directly affected by these changes have in many cases, adapted to the human interventions.

Eastern green snake at the bird bath.

Photo: Charles Botha

Apart from fossilised evidence and historical records, we still have a limited knowledge of what was living on the planet at the time of our arrival, and new plants and animals are being discovered every day. But we’re certainly not entirely sure what we’ve forced into extinction over the same period. Snakes were never top of man’s ‘must have’ list, and anyway, it’s highly unlikely that we considered a ‘slight change’ of habitat to be hurtful in any way. But it’s no longer slight. The recent and more regular radio reports on falling dam levels, melting icebergs and rising sea levels – all temperature related – warrant extreme concern.

The night adder’s diminishing hunting grounds.

In the beginning

For those of us who believe the scientists, the limbless version of the reptile has been around in various forms dating back over 100 million years.

Legless skink. An early fossorial relative.

Photo: Nick Evans

The more commonly known by us came into being later, after the Python came the vipers, about 60 odd million years back. Then came the colubrids – the either non-venomous, or mildly venomous (with the exception of our Boomslang and the Vine snake), followed by the elapids – the more dangerous front-fanged snakes such as the Cobra and Mamba, which started arriving from about 36 million years ago. (ref; Chris Mattison. The Encyclopedia of Snakes. 1995)

For as long as snakes have been on this earth, the various species have had to keep up, and adapt to the changes taking place in their lives, caused by amongst other things, continental drift and meteorite collisions. They adapted or died. Some of these evolutionary adaptations took place over a period of millions of years, and any species that couldn’t adapt to major changes in its circumstances over such a lengthy period, was probably destined to become extinct.

But then along came Hom.sap. who radically re-wrote the rules.

Change is not always as good as a holiday…

We’re told that 2019 was the hottest year ever recorded on earth. Considering the speed at which temperature increases are now taking place, along with the inevitable consequences on our water resources, one might think that many creatures and plants currently living in our environment, could battle to adapt or evolve radically enough in the time available to them, before this planet becomes uninhabitable.

But there’s a chance that snakes might be seen as luckier than most if this becomes a common trend. Apart from many other myths attributed to them, they’re anything but the slimy, gooey things people make them out to be. They don’t perspire in the accepted sense, and the bulk of the moisture they take in is utilised to their benefit. The limited un-utilised portion is passed out during defecation, in the form of a white uric acid paste, in appearance similar to that of our second national flower, gecko poo. Although not as dependent upon water as most of the flora and fauna on the planet, snakes still need liquids.

They obtain much of their necessary moisture from the food they consume, but that won’t suffice. The early morning dew on the ground, leaves and grass, will help for most, but the fish and frog eating snakes who are dependent upon water sources to provide their prey requirements, will need to start relocating as their traditional water sources diminish or disappear.

Even the Python, who often hunt from, or near to dams and rivers, will need to move. My assumptions and speculation expressed in this article apply to what I feel will happen in the future, long before the turn of this century. I’m hoping we’ll be able to control, or even eliminate the man-made causes of our environmental demise before then. One thing is for certain: we need to do something very quickly.

Water shortages will similarly adversely affect other prey animals of the snake, most of which are certainly more water dependent than the snake, and if they need to relocate to better watered areas, snakes, which weren’t created as long-distance travellers, will have to follow suit.

Guttural toad. Food item for night adder, herald and Moz. cobra.

Think if you will, as to why you get snakes around your home. They’re not estate agents looking for stock, they’re adaptive hunters, and you’re the drawcard, unwittingly providing food and shelter. Poor management of our resources, and the additional increases in ambient temperatures will certainly have an effect upon snake behaviour. Snakes in the more tropical regions have a heat tolerance of up to the mid 40 degrees c. thereafter they are in danger. They would be left with the following 3 scenarios, the first of which could be impossible:

  1. Physically evolve to cope with the temperature increases in the time available;
  2. Move to a cooler climate;
  3. Adapt their lives accordingly.

Are we living the frog in the pot of boiling water story?

I was recently working near the southern border of the Kruger Park, teaching people about snakes, and I was interested to find out what the snakes do up there where the climate is generally hotter than here in KZN, to make comparisons on coping behaviour. This was my second trip in two years, and it seemed to have got hotter. When day-to-day ambient temperatures are in the low to mid 40’s there’s little in the way of animal movement. They’re not mad. But an early morning walk along the dirt road adjacent to the fence bordering the Crocodile river, was a revelation. There was a busy mix of fresh animal spoor visible in the dust, ranging from birdlife, right through a diverse range of insect and furry animal tracks, topped off with some reptile spoor. Tortoise tracks, lizard foot and tail trails, and there amongst them, was a wide, flat line left by a transient Puff adder, probably looking for or returning from a handy ambush site.

It was a given. As the bulk of this spoor was not there late in the afternoon prior to my morning walk, most of this action had taken place after sundown, probably whilst I was supping a few cold ones around the braai pit – when the temperature had reached a more animal friendly level. I asked a long-retired ranger friend, what snake movement was like in his days, and as far as he was concerned, little had changed.

Because we have many of the same species here in KZN, I have to think that perhaps they are in fact already surreptitiously adapting. This led me to carry out an experiment here in Cato Ridge on the farm, which could have similar results wherever it’s carried out. I placed a control thermometer on a shaded pole on my west-facing verandah, to record the ambient temperature. I put 3 similar thermometers – all at a depth of 600mm – in arbitrary holes in the open veld where one would find snakes. There are 2 in termite holes, each connected to underground termite warrens, and one in the hollow trunk of about 1.5 metres in diameter, of an old tree in my garden.

Cavity filled tree. Equitable temperature will be a drawcard.

Could this be the ultimate residence.

The results are interesting: the exposed ambient thermometer records collected over a period of 4 weeks varied from a low of 6 degrees C to a high of 41 degrees C changing up or down in relation to the time of day or night. The ambient graph looks like a roller coaster ride. None of the three field-located thermometers registered anything lower than 18 degrees C or higher than 22 degrees C at any time. Their mean average was 21 degrees C – giving me an almost straight-line graph.

If I were a snake, I’d take option three of those I mentioned earlier: I’d start rearranging my life. There could still be time to do so, and provided my food resources remain much the same, I’d be able to cope. Below, I’m taking a broad spectrum look at who will need to do what.

Who will win the race against time?

The fossorial snakes – those that currently spend most of their lives underground – could probably stay where they are. Here in KZN, they’re represented by the likes of the Blind snakes, Stiletto snakes, Centipede eaters and Black snakes, along with the beautiful Harlequin snakes.

Fossorial Stiletto snake.

Photo: Nick Evans

Because of its habitat, the almost fossorial Spotted rock snake lives in a perfectly controlled temperature zone to which it’s become accustomed, and seemingly, this is unlikely to change much. The existing food resources such as termites, burrowing rodents, lizards, and other reptiles would also be unlikely to need to move.

Spotted rock snake.

Photo: Nick Evans

The terrestrial snakes who spend the bulk of their working lives atop the soil surface, are an interesting mixed bag.

The nocturnal hunters, amongst them, the House snakes, Heralds, and Egg-eaters should be able to remain as they are, probably adjusting to the warmer ambient temperatures at night. The diurnal species who operate in daylight, will have to adjust their hunting/foraging habits to suit the higher daytime temperatures. They might have to adjust their locality, particularly the various species of grass, bush and whip snakes that operate in the open, but as with all snakes, that will be dependent upon food source, which will have the same problem with the temperatures climbing. Included in this category, we’ll have the adders, Python, Black mamba and Cobras.

Short snouted sand snake. Terrestrial hunter.

Rural farmer meets a Stripe bellied sand snake.

Variable skinks will also need equitable temperatures.

A puff adder. Ambush feeders might have to adapt.

Building site resident. Juvenile python.

Mocambique spitting cobra. A frog eater of note.

The arboreals – the tree specialists. Included in this group are the Boomslang, Vine snake, and Green mamba. Because of changes – primarily deforestation – to their more specialised habitat in the tree canopy, they have had to make adaptations to the way in which they source their food.

Female boomslang. Queen of the Canopy.

Vine snake. Twig snake. Bird snake.

Photo: Marius du Plessis

Some members of the group seem to be more adaptable than most.

Unfortunately, not all.

Our Green mamba only lives in an ever-diminishing forest habitat close to our eastern coastline, which will eventually be affected by sea level rises. I’ve heard reports, and seen some of the evidence, of Boomslang and Vine snake being found in less forested areas – those that still attract their staple diet, nesting birds. An encouraging indication of their acute awareness of the changes in the environment.

Dietary staple for the arboreals.

Considering the fragile interdependence in our ecosystem, should temperatures continue to rise at the current rate, adaptation for many, could become a hill too far.

Author photo: Pat McKrill

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.

Learn more on his website, Snake Country.