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Nothing in the Kalahari goes unnoticed, least of all by its inhabitants. And as the young Camelthorn tree  (Acacia erioloba) begins to make headway, filling out its branches and trunk, all manner of creature decends upon its vicinity, eager to take up a piece of its prized real estate. Out here the Camelthorn tree could quite easily be considered a ‘key stone’ species (one which is seen as intricately linked into the relationships of several other species, and as such is considered vital to the continued well-being and survival of those dependant species).

First on the shopping list of species to take up residency might be a small not easily seen character. A member of the tick family, the Tampan tick. Curiously, this creature doesn’t like the hot weather, and so seeks out the cooler shaded spots under trees, where it positions itself a few centimetres below the surface. Here it sits and patiently waits for an unsuspecting mammal to find shelter out of the hot midday sun. Sensitive carbon dioxide receptors detect the respiratory activity of mammals, quickly alerting large numbers of these blood-suckers to surface. Once on a host, the ticks engorge themselves on an animals blood, with the animal totally oblivious to the attack. How? Nature has a way of evolving strategies. And this particular one involves a weak neurotoxin found in the saliva of the tick. What this does is deaden the flesh and nerves around the bite site, allowing the tick to drink till its belly is full. Remember this next time you’re looking for a shady tree to picnic under while in the Kalahari.

Swinging to the other extreme are the impressive sociable weavers (Philetairus socius). These amazing birds live together in large colonies within the support structure of the mature Camelthorn tree. Constantly bringing grasses to add to the nest, these apartment buildings of the bush can grow into massive conglomerations of savanna grass, sometimes consuming entire trees. Weighing up to 1 Ton (1000 kg), its not uncommon to have the thick branch of a Camelthorn break under the tremendous weight of the colony, especially after a heavy summer thunder shower. These colonies are home to several generations, with up to 300 birds living in a large colony.

Of course all their twittering and breeding doesn’t go unnoticed. The ever-resourceful Cape Cobra (Naja nivea) can sometimes be spotted tactfully moving from one nest hole to the next looking for chicks. This snake lays about 8 – 20 eggs in the summer, so it needs to find a good source of protein. And the sociable weavers who love to breed all year are perfect. By age one the bird is already feeding its siblings. That’s right…its brothers and sisters. Its called co-operative behaviour and is a survival mechanism to ensure species continuation. These birds are truly remarkable, and should a nest be robbed by a Boomslang/Tree snake (Dispholidus typus) or Cape Cobra, the birds will help feed their neighbours young, whilst they wait for the female to lay a new batch of eggs. These snakes can sometimes take up residence in the colony, raiding the nests daily. And one researcher recorded a period between September and April where a Boomslang repeatedly raided a specific nest under observation in which 8 broods had been eaten. For 7 months the parents had produced young, and every time the young had not lived long enough to be able to fly. The Honey badger has also been recorded digging into the nest from the top in order to reach the nesting chambers, leaving a telltale roof hole in the process.

There is however some protection afforded to these birds in the form of the Paper Wasp, who chooses to build its colony under the nest in the shade. Any threats to its nest and the wasp will attack. Furthermore, the Pygmy falcon (Polihierax semitorquatus, 19.5cm tall) also chooses one of the sociable weaver compartments in which to roost. And one can quickly spot this by standing under a weaver colony and looking for the telltale signs of white droppings at the falcons chosen compartment. A single pair of Pygmy falcons will either utilise a colony from the sociable weaver or the Redbilled Buffalo weavers (their nests are single grass nests with up to 20 nests in a tree). Then there is the roof top – the place above all the compartments where some larger birds find a roost. Owls, Eagles, Vultures and even Geese will make use of the comfortable platform. Whilst Lovebirds, Barbets, Tits and Finches have been recorded utilising the compartments underneath. So the weavers are afforded a certain degree of protection from these associated relationships.

The wonderful thing about the weavers nest is its ability to serve as a thermal regulator against the extreme Kalahari temperatures. Come winter the outside night temperatures can drop to below freezing, whilst inside the nest the temperature is kept at around 23°-25°C. This is partly the result of the birds huddling together (up to five per compartment), and also the insulating effects of the thatched grass architecture. The same could be said for the summer months when temperatures become too hot – things inside the colony tend to stay in the mid 20’s, with bird’s opting to retire to one per compartment.

The Camelthorn pod or fruit is quite hard and not easily broken, but two animals which favour this during the late winter months when food is scarce are the Gemsbok and Eland. In fact, this tree cannot really propogate without the help from these herbivores. And the timing of eating these seeds allows for a perfect synchronicity, for as the seeds pass through the digestive system and are softened, they exit the animal ready to be germinated in a steaming pile of dung. Just as the summer rains arrive.

This tree is a remarkable example of how a fragile system such as the Kalahari can survive and flourish even in the face of extremes. Where one species supports a myriad of lifeforms. And I’ve not even touched on the insect life found on this tree and the associated mammals who feed on them. On my night drives in the Kalahari, I would regularly spot Eagle owls, Striped Polecats, small-spotted Genet, Pearl-spotted owl and the occasional African Wild cat moving about its branches. Clearly these animals used the tree in their nightly foraging sorties. I can only think of how brilliant an example this tree is in highlighting the interconnectedness of life, and how each species is dependant on the other for its continued survival and well-being.