Deep in an underground cave, an African Savannah elephant is on an unusual mission. In total darkness, she’s digging out salty rocks from a 24 million-year-old volcano. This is the only place on earth where this exceptional behavior can be observed. On the border between Uganda and Kenya, Mount Elgon is an extinct volcano with a crater, that’s 20 kilometers wide. It was once Africa’s highest mountain far exceeding Kilimanjaro but millennia of erosion have reduced Its height to 4321 meters. On its forested eastern flank. Several groups of caves lead deep into the volcano. Elephants forage during the daylight hours in the thick groves of bamboo. As herbivores, They receive most of their nutrients through digested vegetation or water if these sources don’t meet their dietary requirements.
They supplement them by eating soil or rocks but the elephants here have taken this phenomenon one step further. When the sun goes down the animals make their way up the slopes of Mount Elgon. The track leads to a dark entrance. Behind the waterfall lies Ketum cave a 150 meter long 60 meters wide and up to a 10-meter high deposit of life-preserving salt.
At the cave entrance, large footprints are evidence of the elephant’s visit. Deep scratches on the walls and roof are the first signs they’ve been quarrying with the mineral-rich rock. But most of the activity takes place even deeper underground. At least a dozen elephants file into the cave. It is so narrow in places. They have to squeeze their bodies along the passage.
All the elephants are female some are pregnant while others have brought their offspring with them. Female elephants need large amounts of minerals during pregnancy and lactation and here they can find them in abundance. An elephant visit might last up to six hours but not all this time is spent mining rock finding their way through the cave takes time too. This young elephant navigates in total darkness using its trunk. It will take many visits for it to learn the intricate structure of the cave. The elephants can’t just lick the rock their tongues aren’t long enough instead they scrape the salty earth from the walls with their stuffy tusks and collect the mineral-rich sand in their mouths. The rocks are rich in Calcium Magnesium and Natrium. A study examining samples found, they contained more than 100 times the amount of Natrium per gram than the average level found in plants. These walls are examined for every last grain of mineral. At a steady 13.5 degrees celsius the air in the cave is the pleasant night on the mountain usually gets a lot colder than the constant temperature in the depths of the caves. Elephants have been visiting these caves for centuries possibly even millennia. Over time they’ve modified and enlarged the caves digging their way deeper and deeper into the mountain creating chambers. That can be up to four meters tall. After hours of salt mining, the elephants stop work and leave the cave. The route into the cave and the technique of scraping the walls are passed down from generation to generation. A a unique tradition that only exists here on mount Elgon