HI, and welcome to my blog! I am a field guide in a private game reserve in South Africa and below you will find stories and pictures of my amazing job!

December 13, 2011

A Tall Story

The lowveld is home to one of the richest ecosystems, in terms of biodiversity, to be found on the African continent.  Perhaps the most unique and recognisable of these miracles of design is the giraffe.  If you take the big cats out of the equation, it is easily the animal that we, as guides, receive the most requests for.  In fact, a recent survey to establish people’s perception of what they considered the most iconic animal in Africa turned up surprising results:  the giraffe romped to victory by an overwhelming margin, eclipsing even the odds on favourite, the lion.  One can only marvel at the evolutionary adaptations that have enabled the tallest animal in the world to flourish.  Its elegant design means that it can feed on leaves that none other of its antelope relatives can.  Therefore, while the smaller antelope such as impala, kudu and, bushbuck compete for food at the lower levels, the imperious giraffe can happily browse at a relatively uncontested level.  Its only rival at this height is of course the elephant but their varied diet and penchant for grass during the wet season means that the competition is negligible.

4 Giraffes emmerge from the surrounding bush in a tangle of necks

               The giraffe’s unique design might enable it to dominate this ecological niche but it comes at a price.  The physiological adaptations in the circulatory system have had to evolve to combat the challenges of supplying and controlling the blood flow around such an unnaturally shaped body.  A common misconception is that the heart is unusually large to facilitate the pumping of the blood up the neck, to the brain.  Recent studies have shown that the heart is no bigger in size in relation to other animals.  In fact, all animals have a heart that weighs approximately 0.5% of their total body mass.  What the giraffe’s heart does possess however, are thicker walls, and it is here that the giraffe is able to generate the pressure needed to scale the heights of the neck to the brain.  The giraffe also possesses a remarkable network of valves at the base of the brain that can control the flow of blood.  This is imperative to avoid blacking out when bowing down to drink for example.  This organ, known as a ‘rete miribile’ counteracts the forces of gravity and ensures that the flow of blood remains regulated. 
               The list of other evolutionary adaptations are far too numerous to mention in the blog but suffice to say that the giraffe is probably one of nature’s most ambitious engineering products.  The lack of similar animals living anywhere in the world today is testament to that fact.  Its closest relative is the okapi of central Africa but this in itself is a very odd looking individual – a cross between a zebra, horse and giraffe, I encourage you to check it out!
A stretch of giraffe glide across the horizon

               For fear of lowering the worryingly intellectual tone of this blog (having just read it so far…), let’s be honest, the giraffe is just really really pretty!  The elegant structure we have discussed already, but let’s not forget their luscious lashes.  They are the envy of every model, but as with everything, they serve their purpose: the giraffe love both buffalo thorns and acacia trees.  Both are heavily armed with thorns and spines; and so while they may look like a fashion statement from a Vogue magazine, they in fact protect the eyes and allow the giraffe to feed more safely. 
               Beautiful and docile animals they may be, but when the chips are down, males are capable of delivering fearsome blows with their horns.  Officially termed ossicones, these protrusions are in fact only cartilage when born and take up to 5 years to fully fuse to the skull and turn to bone.  Calcium is deposited on the skull throughout a male’s lifetime and this manifests itself in the bald caps to the ossicones (and also lumps of boney material on the forehead and above the eyes.)  This allows for greater weight and therefore greater impact during fights.  The momentum generated from swinging such a long neck is huge and during a full bloodied exchange, the impact can be enough to knock an opponent off his feet!

Two young males engage in a mock sparring session

The ever present oxpeckers are displaced from the giraffes during the exchange

               Full on fights are rare to witness but often we are graced to see young males sparring with each other.  This behavior is essential in learning the techniques to one day challenge for mating rights.  The images of entwining necks that follow are as close to art that one can experience in the animal kingdom. Each move is easily countered by the opponent and the flexibility of the necks during these displays defy belief.  One cannot help but sit mouth agape at the beauteous movements of the ensuing ballet.  It is like watching the rehearsal for a fast paced martial arts movie scene where the participants practice in slow motion.

The oxpeckers scatter as they try to evade the swingng necks

After the fight, the youngsters rub necks as if to assure each other that are no hard feelings

Regardless of this element of violence within their society, to watch them glide through the bush with their gentle rocking motion remains one of life’s great experiences.  They are a true enigma of Africa – grossly out of proportion, yet wondrously elegant.  Men and women of all ages react with the same child-like delight and all tend to have a dopey smile on their face while they watch.  It reminds me of a baby being confronted with a colourful and musical mobile for the first time.  Merely watching them float from tree to tree as they browse brings with it a sense of relaxation – they are nature’s equivalent of a fish tank or lava lamp.  As a guide, one often doesn’t need to comment on their actions; and sometimes to say nothing is the best commentary of all.