OK, so steenbok are able to utilise vegetation that they normally don’t eat and to which they have had no previous exposure. They are not unique, many animals do just that. This could be put down to either opportunism or good fortune or an example of their resourcefulness, or as I suspect, a little of everything. Intriguing as this was, it was another aspect of this little antelope’s adaptability that interested me. I was fascinated by the fact that these two delicate little antelope, each a mere mouthful to a predator, were cruising the shallow edges of the dam, nibbling away, fully aware but apparently unconcerned that only a few metres away lay a large crocodile.
Despite a larder of carcasses stashed around the dam, this reptile appeared to be insatiable, taking every opportunity to secure more food. I guess this may be due to the same instinctive response that other predators, such as caracal and leopard, have demonstrated when they raid domestic stock pens. By responding instinctively and taking advantage of the easy pickings, they’re branded wanton killers because of the wasteful slaughter they inflict. The economic losses incurred can be substantial and so they are maligned and relentlessly persecuted by stock farmers.
On the other hand, nobody brands the crocodile at Hide Dam a wasteful killer, despite its stash of two impala and a warthog. No, we rather admire its automatic and unconscious instinct to save for a rainy day. This croc has virtually doubled in size in the last few years, giving us an indication of just how successful this predator is. I also believe it has the advantage of being able to lie comfortably and unchallenged in the centre of a dry season game magnet.
Given the probability that in their respective natural environments, steenbok and crocodiles would probably never cross paths as they occupy totally diverse habitats, how then do the steenbok avoid being taken? How do they know the safe flight distance from a predator they have never seen before? I may be assuming a lot here, but to see the confidence with which these little guys cruise the edge of the dam makes you realise there is clearly more to them than meets the eye. The next time you see one, spend some time admiring these little survivors, they deserve more than a quick glance.
Moving up a few notches on the scale of antelope I admire and respect, kudu have always occupied a special place in my heart; they’re proud without being arrogant; they melt away in front of you without making a rude exit; they are large yet maintain an unobtrusively low profile; and they’re like good house guests who live with you, but also allow you your space. So it goes without saying that nothing pains me more than to see such magnificent animals reduced to skin and bone. These majestic ‘grey ghosts’ of Africa, although extremely versatile, are not immune to drought, and as we’ve observed lately, have been utilising a wide range of vegetation to get by. Among the known variety of browse they select are the aggressive, invasive, alien and thought to be noxious cocklebur and then the indigenous, but not endemic, Aloe marlothi, and the local aloes which are eaten to destruction. The desiccated, dried-out leaves of the large-leafed rock fig Ficus abutifolia are picked up off the ground and eaten with apparent enjoyment. Three enormous kudu bulls had become quite used to my running routine over a period of weeks and as time passed, so their required flight distance decreased. One afternoon, they allowed me so close I could hear them crunching the dry fig leaves. It sounded as though someone had just offered the Pringles around.
I almost hesitate to report that since writing this, the lions have killed the biggest one of the three kudu behind the laundry near my office. Realistically, I must admit that this was probably due to him being older and slower than the other two.
This variation of diet can be understood to be an adaptive response to the drought. The question is, though, if they enjoy bitter dry vegetation, why don’t they eat the prickly pear cacti which, although classed as exotic and invasive vegetation, are relatively juicy and sweet? It is well documented that farmers in the Karoo have, in times of drought, fed their livestock on prickly pear leaves, and I know that a particular species of this plant is used to make tequila – which, I am told, has positive effects on humans. I suspect there may be a link between gut parasite loads, which we know tend to proliferate when an organism is under stress, and the relatively high intake of bitter and/or unpalatable vegetation at this time of the year. Could this be a conscious response for medicinal purposes? Or do these kudu know something we don’t?
If you come across a thin lion at the moment, it won’t be due to malnutrition, it is either sick or injured. There is just so much available to eat due to the weakened condition of many prey animals. Warthog, for example, which are usually tucked away in the relative safety of a cosy old aardvark burrow at sunset, have become crepuscular and are now often found feeding late into the evening. Their poor night vision and being out when most predators are active, is a deadly combination. It doesn’t come as any surprise, then, that the game census figures of September 2008 indicate a substantial drop in the warthog population, nearly 60 per cent down on last year’s numbers. On the other hand, they respond quite dramatically in good rainfall years, when their numbers can triple!
Initially, predators are not adversely affected during leaner periods; on the contrary, they make hay while the sun shines, taking advantage of higher than normal concentrations of prey on the seep lines and the riverine floodplain. Prey animals are also relatively easy to catch as they’re totally focused on finding enough to eat and therefore not as alert.
Then, as if this was not enough, as the season gets progressively drier, the energy value of available vegetation drops, resulting in physically weakened animals becoming more vulnerable to predation. But the big wheel turns, and as I’ve said, the prey species numbers crash in a drought and then when the rains arrive, the survivors spread themselves over a relatively big area.
The larger predators, particularly lion, now find it more difficult to secure enough food. Prides will set out to hunt, leaving young cubs behind, then when a kill is made, often after covering many kilometres, it is usually completely consumed, and nothing gets back to the cubs. This also adversely affects many of the sub-adults that are denied access to kills by the hierarchy of the pecking order. These inexperienced youngsters are then forced to move off and search for food on their own. This often takes them out of the reserve from where they hardly ever return.
A lioness nursing young cubs will apparently pass up larger prey species in preference to smaller prey which are hunted during the day – often uncharacteristically, in the heat of the day. Do they know the cubs are vulnerable to other predators and so adapt their hunting techniques, or is it that they cannot risk injury because they are the sole providers? One thing is for certain, there is no shortage of prey on the riverine habitat in the dry season, and so hunting forays do not take her far from her cubs and are usually brief. Hunting success in terms of their kills-to-attempts ratio also appears to be relatively higher, enthralling many privileged shareholders who sit on the decks of their lodges and witness these kills.
In drought conditions, animals will utilise whatever they can find wherever they can find it, in an effort to maximise their forage intake. They will frequent unfamiliar habitat or places that are mostly man-made and which under normal circumstances would be avoided. The railway line is a good example of something unnatural that instinctively animals don’t like. This is demonstrated by young animals that need considerable coaxing and encouragement to get them to walk across it. I’ve seen giraffe and kudu cows moving back across the tracks to feed juveniles who won’t cross despite their hunger for milk. For weeks, the youngsters refuse to follow their mothers across the granite chips upon which the sleepers are laid. Not only do I think the shiny metal tracks put them off, I’m convinced the coarse gravel stone bed is too loose and insecure for these ‘tenderfeet’. Until their hooves harden and they become accustomed to the tracks, all their instincts tell them this is not a natural part of their new world.
Another reason wildlife use this hazardous man-made habitat, particularly in the
dry season, has to do with finding enough food in times of scarcity. At the end of a reasonably good season most of the grass matures and then dries out, with the only green grass to be found being that growing in low-lying areas or seeplines. The railway line, on the other hand, in the same conditions, will always have some green grass throughout the winter months irrespective of topography. The sharp granite chips that make up the rail bed undergo a level of expansion and contraction that creates an ideal medium for condensation. The retention of moisture is facilitated in this mini rock pile. To add to this, every so often there is a little phosphoric acid spillage from the trains and this combination becomes ideal plant food. This ‘nourishment’ may be the reason why vegetative production along this otherwise ugly, unnatural blight on our reserve’s landscape is relatively good. The negative impact is that due to resource stress brought on by the prevailing dry conditions, animals, particularly the browsers, are attracted to this ‘danger zone’.
The danger to our wildlife from both the trains and heavy vehicles using this route is evident by the number of deaths we record in the dry months. To this end, every growing season, we employ a team of men to remove all palatable browse along the line, particularly in the cuttings. This vegetation control is necessarily confined to the section of the railway within our reserve’s boundaries. In a single week prior to me ‘getting the hump’ and placing more speed humps on a section of the rail road, we lost a sad list of two steenbok, two squirrels, two hornbills, a honey badger and an impala to speeding trucks. This was on the short section between the Sable Dam and Warthog Pan turn-offs. Only those animals seen or physically collected are recorded. Realistically, this figure could be much higher if we consider those that get away injured to die later, or those that have been scavenged by predators and we don’t find.
So, when you admire or curse these ‘tank traps’ as one of our shareholders refers to them (or ‘mumps’ – Mario’s bumps – as my editor calls them), know that they’re not there for decorative purposes. If I could put ‘mumps’ on the railway tracks themselves to slow the trains down, I would do that as well.
Baboons have responded to these adverse conditions with one aim, and that is survival, plain and simple. As part of their strategy, they have broken up into smaller, more effective foraging units ranging from single adult males to groups of large males numbering three to six individuals. Only the strongest females are seen with a dominant male. These groups seldom number more than 10 to 15, this being drastically down from the normal troop size of 40 to 60. Other signs of stress are that adult females are not coming into oestrus, pregnant females are not lactating, and mothers hang on to new-born babies who have died from starvation for a day or so before they drop them.
I have recently recorded cases of infanticide and cannibalism. In one instance, a baby already past the ‘black hair phase’ was the victim. A case of cannibalism was reported from a neighbouring property where the carcass of a dead baboon was stolen before it could be incinerated and was then eaten. In all the instances the perpetrators were large adult males. On another occasion, we found a number of dead baboons in one location at one time, which raised some concern as we suspected a virus might be responsible. We needed veterinary certification of our suspicions, but as Gerrit was bobbing about on a rubber duck in the Indian Ocean, the state vet was called in to carry out the autopsies. His examination revealed the cause of death to be starvation, a direct result of resource stress.
I suspect the reason baboons have taken so much strain this particular winter is more than likely the convergence of a number of inter-related factors:
the 1996 flood washed away a large percentage of riverine fruit trees and shrubs and recovery has been slow
the pylons for ‘our’ power lines have created roosting areas that are safe from predation, this in turn leading to an increase in numbers
supplementary winter feeding of at least two troops by a local rehabilitation centre has artificially maintained and promoted more numbers than the habitat can naturally sustain
the unfavourable rainfall pattern last summer resulted in low vegetative productivity
resource competition for fruit and fruit trees by elephant, whose feeding habits have resulted in the large-scale destruction of marula and knobthorn trees, both of which are important food sources for baboons
the change of their legal status from vermin to animals that require a permit before they can be hunted or captured, has contributed to an increase in their numbers
an increase in human activity in the area (builders, etc), which resulted in more waste being produced. This in turn provides more opportunity for baboons to scavenge dumps and garbage disposal units.
As you can see from the list above, which is far from exhaustive, our reserve presents its baboon scenario in a contradictory fashion. We have created a favourable environment which encourages a proliferation of their numbers which nature then ruthlessly culls.
Of all the herbivores on the reserve, wildebeest and zebra appear to be the least affected by the drought, particularly wildebeest, which have not only increased by 25 per cent this year, they all appear to be in good condition. I also suspect this unusually high increase can be attributed partially to us having benefited from some recruitment from the neighbouring Klaserie reserve. At the same time, who has ever seen a thin zebra? It seems they die before becoming emaciated. As desperate as things may seem to be, the reality is that not only are these dry spells regular occurrences, but they are a necessary process governing our ecosystem.
When you see a wild leopard feeding on a freshly killed impala a few metres away, you are privileged … privy to one of Africa’s most rewarding scenes. The antithesis of the drab, drought-stricken, apparently lifeless bush framing the scene, the leopard is vibrantly beautiful, alert and in the prime of its life – as was its prey until its final moments. It is difficult to understand how an animal so well-designed, so perfectly proportioned and in such superb condition could be the product of the surrounding bush, which to the naïve eye appears dead and unproductive. What you are seeing is the tip of the production pyramid, the top of the food chain.
It is this seemingly barren habitat that moulds the building blocks, making up the base of the pyramid, which itself is the product of millions of years of exposure and adaptation to adverse climatic conditions. Much like the dry spell we are experiencing now. The diversity of life that can be sustained by a system such as ours has proved to be rich enough to culminate in such rewarding sightings, over and over again. Many recent visitors who did not let the late winter appearance of the bush depress them, were rewarded with leopard viewing at Big Dam that would be hard to beat anywhere.
I end this chapter with a poem written by my daughter Eleana when she was 13. In her own way, she captures the essence of drought and its effects. Of course I am proud of her, she is my daughter. At the same time, I am humbled by her insight into the phenomenon of drought, something few people of her age, living in a First World environment, are exposed to, and who are possibly the poorer for it.
Drought
Disaster, death and worst of all – fear,
This is how we know that the end is near.
Animals suffer and starve from it,
We hate it with all our heart – we don’t like it a bit.
People concerned try and sort it out,
This painful, pitiful, merciless drought.
Of course we know that there is nothing we can do
Rain comes when it wants to, but then its drops are so few.
So we ask ourselves the question ‘Why?’
And gaze towards the cloudless sky.
The plants turn grey and shrink to the ground
There is no hope any where to be found.
All we can do is hope and pray
That rain will come soon some day,
The grass will be green again –
And the flowers will bloom
Let’s hope this all happens – v
ery, very soon…
Global Warming and Rainfall Patterns
February 2007 … revisited 2009
We now know that global warming is neither a Greenie scare tactic nor an unproven theory. Rather, it is a scientific fact that the globe is getting warmer and the world’s climate is changing as a result of greenhouse gas emissions. When the mercury shot up to 45ºC in December, evaporating what little moisture there was, withering the new growth of grass and turning it from green to blue grey, exacerbated by the total absence of rain in that critical month – well, I was convinced.
In my world this was a sure sign, the beginning of the end in this rain-driven environment. As the northern lowveld is already hot and semi-arid, the change in these two important limiting factors, namely more heat and less rain, would undoubtedly have a negative effect on the ecosystem. Although I was understandably depressed, before reaching for a double dose of Prozac and looking at retirement homes in Greenland, I was reminded of Christmas 1982, while working in Botswana’s Tuli Block.
The day was spent up to our chins in the lukewarm, but nonetheless relatively cool water of a concrete reservoir as the ambient temperature was hovering around 47ºC in the shade! The cicadas appeared to be the only creatures unaffected by the oppressive heat; it was almost as if, the hotter it got, the more intense their staccato song. It would be interesting to know at what ambient temperature they stop ‘zizzing’. Nothing else except them dared expend a single kilojoule of energy – even the emerald spotted wood doves were conspicuously quiet. A number of small birds of various species congregated on the concrete stoep floor of the main house, obviously the coolest spot they could find. I recall that the fork-tailed drongos and white helmet shrikes appeared to be particularly susceptible to the heat as many of them actually died. An African goshawk squatted on its long legs, undignified, open-beaked and wide-eyed, surrounded by dozens of panting and dying birds. Clearly focused on staying alive, it showed absolutely no interest in the other birds and they in turn were too stressed to care or move away.
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