30 SWARA October – December 2007 Maps of Kitum Cave

1 Maps of Kitum Cave (1), Mackingeny Cave (2), sections of Kitum Cave (3), and sections of Mackingeny Cave (4). 30 SWARA October – December 2007 2 behaviour 3 Mount Elgon’s ‘elephant caves’ Joyce Lundberg and Donald McFarlane contemplate and map the extraordinary underground attractions of western Kenya’s Mount Elgon National Park. 4 SWARA October – December 2007 31 ne of Kenya’s least vis- that are far too busy eating the herbivore ited parks, the Mount equivalent of chocolate mousse to take Elgon National Park much notice of their potential fate. Oprotects a narrow band The salts are mainly mirabalite, of forest climbing the eastern flank sodium sulphate (commonly called of East Africa’s fifth highest mas- Glauber’s salt), which grows out sif, standing 4,321 metres (14,178 from the walls and can form curved crys- feet) above sea level (see map below). tals resembling pig’s tusks. The crystals are For most visitors, the Park’s principal licked off the wall by buffalos or scraped/ attraction rests in its suite of unique caves, gouged out by bushbuck and elephants. of which the Kitum and the Makingeny Buffalos cannot scrape the rock themselves, Caves are best known. Used by the Elgony so they eat mainly the leftover bits dropped people for centuries, the Elgon caves came by the elephants. The marks left by bush- to wider attention through the writings of buck teeth and elephant tusks are clearly Joseph Thomson (Through Masai Land, identifiable on the cave walls. 1885), and are thought to have been the These marks should not be confused inspiration too for H. Rider Haggard’s with the marks left by pick axes wielded by best-selling novel King Solomon’s Mines, humans who, until the late 1960s, removed also first published in 1885. sections of the salt-rich rock to feed to their The caves are often assumed to be lava cattle. The effect of all this salt mining (or tubes – pipe-like passages winding through ‘geophagy’) by animals and by humans lava flows – because they are in volcanic provides a clue as to the true origin of the rock. The rock is not lava, however, but caves. volcanic agglomerate: a mass of small and Places where elephants have been most large blocks of old solid lava ejected from active in their subterranean geophagy are an erupting volcano along with new fine- marked by substantial (elephant-sized!) un- The three stages of cave grained ash that binds it into a solid rock. dercuts in the sides of the caves from the formation. The eruptions felled large trees, the fossils floor up to tusk reach. This also happens to of which (or sometimes just trunk-shaped large blocks of rock that have fallen from holes) are still entombed in the rock. the roof – these become modified into The caves are not tube-shaped either; mushroom-shaped rocks on stalks which rather they have a central passage, semi-cir- eventually get so thin the blocks fall over. cular in cross section and opening out into Elephants are active throughout the dome-like chambers floored with piles of caves, even in the darkest inner recesses. collapsed rock slabs from the roof. Humans have also carved alcoves, but they So, if they are not lava tubes, then how remained closer to the light, so the alcoves did these caves form? they carved with their pick axes are not The caves have long been known to at- found deep inside the caves. People also cut tract elephants and other animals including neater roofs and sorted the material more buffalos, bushbuck, hyenas, leopards, and carefully than the elephants; they took the rock hyraxes. Over many years, Ian Red- ash rather than the large blocks of lava that mond observed the elephant activity within would be too hard for the cattle to eat. Hu- the caves. He and the BBC have fascinat- man mine sites can be identified from the ing film footage documenting night visits pick-axe marks, the rounded leftover lava made by animals to Kitum Cave (Natural blocks, and the flat ceilings. World: Elephant Cave; BBC/Animal World, Mining of salts by animals certainly UK, 2003, directed and produced by Van- provides an obvious means of creating essa Doyle/Berlowitz and Justine Evans). large alcoves in the walls. However, it turns The herbivores (elephants, buffalos, out that the caves are not quite so simple. bushbuck) enter the dangerous environ- The streams that flow down the mountain ments of the dark cave interiors to consume sometimes encounter bands of resistant salts that effloresce from the cave walls. The rock and form waterfalls. Each cave begins carnivores enter the cave to prey on animals as an initial cavity behind such a waterfall, 32 SWARA October – December 2007 the resistant band’s forming the roof and as the focal point for outbreaks of the the cavity’s forming in the less resistant deadly Marburg disease, a severe form of rock underneath. The salts crystallize out hemorrhagic fever caused by a filovirus in from the damp, bare rock of the cavity, the the Ebola family, recounted in rather sensa- elephants arrive, and the cavity is enlarged tionalised form in Richard Preston’s book, (Stage 1 in Diagram). The Hot Zone (1994). This mechanism alone does not seem Efforts to identify the vector of the vi- to be sufficient to form big caves. The big rus, undertaken in the cave in 1987, were caves all form along a band of impermeable unsuccessful, and thousands of people have green clay that traps water above it (called since visited Kitum Cave without suffer- a ‘perched’ water table), forcing ground ing ill effects. Nevertheless, recent research water to flow in a narrow zone in the rock elsewhere has identified the Ebola virus in above the clay and confining the majority Rousettus bats, so entering the bat roosts is of the evaporation to the rock surface, and inadvisable. It can also be unpleasant, as the The marks left by bushbuck teeth thus the efflorescing salts, to the zone above ceilings of the roost are covered in a living (left) and elephant tusks are clearly the clay. The ground-water flow, though mat of blood-sucking riduviid (bed-bug identifiable on the cave walls (bottom slow, inexorably saps away the band of family) Cimex bugs! In any case, exploring right). These should not be confused clay, causing continual undercutting of the the bat roosts is highly disruptive to the with the marks left by pick axes clay band (helped by small animals such as bats themselves. wielded by humans (top right). bushbuck). The rock immediately above the green clay then collapses (Stage 2), its pieces’ providing rich salty meals for herbivores, but unfortunately occasionally also trapping the eater – there are often bones to be found under rock falls. he animals can reach up only a few metres. Thus the cave should be wide and low. Since they are Thigh and dome-shaped, it is obvious that the main passages and chambers have been shaped by roof collapse (Stage 3). We might expect the collapsed pieces to remain in a pile in the passage, but here, while the end chambers are full of recently fallen slabs, the passages are clear of rock debris. It appears that, after some time, geophagy has effectively removed the blocks. An added effect of roof collapse is that it allows the animals to climb on top of the Mount Elgon’s underground elephants blocks to gain access to higher parts of the represent a unique aspect of elephant be- cave walls, resulting in the creation of new haviour that has been learned and passed alcoves at higher levels. down over countless generations. That We now have several mechanisms for chain was almost broken in the 1980s when creation of the caves. But this is not the intense poaching activity around the caves end of the story. More subtle, yet wide- decimated the herds. Today, the remaining spread, processes include the chemical elephants are threatened by the encroach- effects of the biological activity of the many ment of farming, which has moved ever thousands of bats that inhabit the interior higher up the mountain and now straddles domes – along with the acidic guano that the elephants’ migration route to the south piles up on the floor. as they move around the mountain. The ecology of the Mount Elgon caves Fortunately, the Kenya Wildlife Service is both diverse and complex. Besides ad- has assigned a full-time tracking unit to mitting the geophagous mammals and keep a close eye on the elephants and to Further Information their predators, the caves are roost sites intercede in any potential elephant-human A field guide to the caves, cave maps, and for colonies of tens of thousands of fruit- conflicts. While the Born Free Foundation a technical account of the geology and geo- eating ‘Egyptian’ flying fox bats (Rousettus in the UK is supporting and bearing morphology of the caves can be downloaded aegyptiacus) that play a vital role in much of the cost of the programme, the from < http://faculty.jsd.claremont.edu/ seed dispersal in the forest. Smaller continued survival of Mount Elgon’s dmcfarlane/MtElgon/index.htm >. colonies of insectivorous horseshoe remarkable salt-mining elephants Information on the Born Free Foundation’s work bats also live in the caves. Ominously, will depend on visitor interest and on Mount Elgon is posted on < http://www. Kitum Cave has twice been implicated charitable donations. bornfree.org.uk/elefriends/elgon.htm >. SWARA October – December 2007 33.

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