Psst!! Behind you!" It was a moment of high comedy and surging adrenaline.

We were on foot in the forest, trying to film a herd of Elgon elephants for an American television series Wild Things. The elephants had crossed the track moments before our arrival and all eyes were on the dense thicket from which the cracking sounds of elephants feeding were emanating....until one of the film crew noticed that we were looking the wrong way!

Not all of the herd had crossed the track. Behind us, a female and calf were standing nervously at the grassy verge. She had just plucked up the courage to cross when a big bull elephant emerged to do the same. He strode boldly into the middle of the track and faced us, "standing tall" - ears outstretched and head held high - just a few paces from where we were "standing small", feeling vulnerable as the cameraman caught the action.

Suddenly, the elephant's nerve broke and he turned tail and fled into the thicket, causing panic among the others, who we heard rushing away through the forest.

"It's so sad," I said to the camera, "that such magnificent animals are so terrified of people." The reason for their fear, of course, is the same reason that I became involved in the ivory debate back in the mid-1980s: poachers.

When I first visited the caves of Mt Elgon in 1980, elephant poaching was not a problem in the park. I came with a team of Operation Drake volunteers. They were building a tourist path to Kitum Cave so that human visitors would not have to enter the cave by the same route as the elephant and buffaloes.

We also monitored the cave for animal traffic and my imagination was fired by the thrill of crouching on a star-lit rock in the cave mouth, sensing elephant feeling their way into the blackness of Kitum's entrance chamber. Elephant rumbles are exciting enough from close quarters on a game drive - imagine how they feel reverberating around a cave in total darkness when there is no vehicle to offer a sense of security. I was hooked!

Since that first time, I have spent an accumulated six months or so living in several of Elgon's caves, studying, filming and photographing elephant, antelope, buffaloes and on one occasion even a colobus monkey.

The reason for this unusual troglodyte behaviour in otherwise normal forest animals is salt appetite. The walls of Elgon's caves are rich in minerals which the forest plants, growing in soils leached by the heavy rains, lack. This means that the herbivores must make up their dietary deficiency by finding another source of salts, especially the sodium ions that all animals need. I had samples analysed and found that the volcanic agglomerate from the caves contained more than 100 times the level of sodium in elephant food-plants. This confirmed that the caves are simply subterranean salt licks.

But why do the animals go deep into the dangerous dark zone, where there are deadly crevasses, possible rock-falls and the risk of being trapped by hyaenas or a leopard? It seems that the mineral rewards are greater further inside. The cave roof is home to thousands of tongue-clicking fruit bats. Recent research indicates that their droppings react with the rocks on the cave floor to form an even more mineral-rich crust. One of my most vivid memories is of fruit bats flying over elephants some 160 metres inside the mountain, lit only by my tiny pen-torch.

With or without the action of bat guano, the caves play an essential role in the ecology of the area. But how were they formed? They are cul-de-sacs, some of them huge, which do not fit the pattern of water-worn cave systems or the lava tubes seen on other East African volcanoes. Many have been enlarged by the picks and axes of the El Kony tribe, or Elgon Maasai. They used to dig out the rock for their cattle to lick and for trading with neighbouring cattle-keeping tribes (until the advent of commercial salt-lick blocks provided a better alternative). In times of war, the caves were used for women and children to take refuge in (along with their beloved cattle), and at least one cave outside the national park was still inhabited quite recently.

In 1982 I visited an old man and his wife there and was interested to note that beneath the years of soot on the cave walls were the clear signs of elephant tusk marks.

Although we refer to an exposure of mineral-rich earth or rock used by animals as a salt-lick, the fact is that elephants cannot lick. Their tongue is not long enough to reach around their trunk and tusks. Instead, they dig with their tusks, scoop with their trunk and grind the lumps with their massive molars before swallowing.

Over long periods of time, this behaviour might be described as erosion by elephant. At most natural, above-ground salt-licks, this can lead to fairly big holes being dug vertically downwards, or horizontally into a bank. In such cases, the roof of any overhang soon collapses with this "mining" activity. But the Mt Elgon caves are capped by a layer of impervious cooled lava - the very reason there are still soluble salts in the layer beneath. If the ancestors of today's elephants began digging at a mineral-rich cliff beneath the lip of the lava layer, any overhang would not have collapsed and a cave would have eventually formed.

Elephant are intelligent, social animals, whose knowledge of local habitat is learned at their mother's side. In effect they have a culture and the use of caves is a part of Elgon elephant culture.

Each new generation would have gone with their herd to the overhang which, decade by decade, grew deeper and deeper. The inevitable conclusion is that these are not just caves into which elephant happen to wander. They are elephant salt-mines, dug over thousands of years by the world's only troglodyte tuskers!

Scraping their tusks against a cave wall every few nights has its consequences for Elgon elephants. Most have short stumpy tusks because they are worn down as fast as they grow. Thus, when I began this work, they seemed unlikely targets for ivory poachers. Unfortunately, the price of ivory in the mid '80s rose to such a level that it was worth killing them, even for just a few kilogrammes of battered tusks.

Many of my study animals were killed in 1986/7 - some ambushed on their way into Kitum Cave. Imagine finding the rotting carcass of an individual you knew well, face sliced off with a chain saw for a speedy get-away. It is hard to describe my feelings, but my response was to launch the African Ele-Fund, an appeal that relies on the goodwill of other wildlife charities to channel 100 percent of every donation into practical elephant conservation projects (and does so to this day).

Two years later, in 1989, the Ele-Fund, along with Care for the Wild, WSPA and Born Free Foundation (then Zoo Check) launched the Elefriends campaign, which helped bring about the 1989 CITES* ban on international ivory trading.

As the market for ivory declined following the ban, so did the poaching - even in parks like Mt Elgon, which lies on Kenya's border with Uganda and suffers from cross-border raids by armed bandits. The villains didn't go away, however. They just turned their attention to robbery, rustling cattle and killing antelope and buffaloes for bushmeat.

By the time of our close encounter with the nervous bull last May, no elephants had been reported poached on Mt Elgon for several years. But it was clear from their fear of humans that the elephants had not forgotten.

Ian Redmond is a Wildlife Consultant specialising in apes and elephants. He is the founder and chairman of the Ape Alliance and the African Ele-Fund, and he enjoys guiding film crews and special interest tours.

Published in Travel Africa Edition Five: Autumn 1998. Text is subject to Worldwide Copyright (c)