The Elephant's Secret Sense: The Hidden Life of the Wild Herds of Africa

The Elephant's Secret Sense

Free Press

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LISTENING THROUGH LIMBS

Do not go where the path may lead, go instead where there is no path and leave a trail.

-- RALPH WALDO EMERSON

I always hate to leave Etosha, but it was early August and the winds were picking up. It was time to pack up the site and head north. Sitting in the back of my truck, I looked through my binoculars at the scrubby horizon dappled with giraffe necks, trying to work up the energy to get my equipment organized when I heard a thick, leathery, swishing sound right next to me. I looked up to see 100 tons of pachyderm pass by, almost tiptoeing, heads bobbing in their Nordic Track-style gait. It was Broken Ear and her family, a group of twenty elephants, headed purposefully toward the water.

I noted when Broken Ear arrived and watched as her family assembled around the water. Being the matriarch, Broken Ear occupied the outflow of the artesian well, which was controlled in the dry season to sustain the large number of animals that depended on it to get through this difficult period. The dominant elephant always got the bestwater.

Broken Ear took a few long draws, rolling up her trunk and placing the water far back in her mouth, head tipped up. A few splashes escaped back into the pool. The howling gusts of wind had stopped, so I could hear the intermittent trickling of water escaping thirsty mouths. They were returning to the waterhole after their visit had been cut short the day before by the arrival of another family group led by a very intolerant matriarch that I called Collar.

Once the little ones had had their fill, they started to play. Young elephants are just as mischievous as lion cubs, always testing their boundaries with adults and jockeying for rank with siblings and other relatives. They stood at the pan's edge, knee-high in water, and tipped over onto their sides to make as much contact with the mud as possible. Then they began to wallow, swatting at each other with their wet-noodle trunks. Their mouths were turned up in what seemed to me like smiles as they wailed and cavorted in the water. The mothers merely looked on and continued drinking.

Reluctant to break camp, I savored the moment. I jealously guarded my visits to this splendid waterhole that the Owambo people called Mushara, after a tree common to this sandy forested habitat, or sandveld, a large terminalia with papery magenta pods (Terminalia prunoides). Mushara is located in the eastern corner of Etosha National Park, Namibia, one of a few waterholes restricted to the public, with the added benefit of having a protected cement lookout, which provided me with a great vantage for my elephant studies. I had a few other favorite waterholes where I would sleep, either in the back of my truck or in a hide. But I had developed a special bond with Mushara because of its remoteness and the number of elephants visiting on a daily basis. As much as I enjoyed the isolation, I was conscious of its potentially negative effect on my preception of reality. I was looking forward to being clean again, having not been able to shower for more than a week, but I was also dragging my feet about leaving the tranquility.

I was not looking forward to returning to my life in the north of the country, the Caprivi, where, despite its remote location, an exhausted community game guard might knock at my door at any minute, having bicycled 12 miles in the heat to assuage the anger of his fellow villagers to report another incident of a crop-raiding elephant. I would miss the elephants of Mushara, which were more isolated from the threats of war and civilization, and head to a place where they were different animals altogether. Many elephants in the Caprivi were still reeling from a war-torn past, exposed to land mines, automatic weapons, and poaching, partly to feed the hungry Angolan soldiers for the last twenty years. And at Mushara, I, too, could be a different person.

I first came to Etosha National Park in 1992, contracted by the Namibian Ministry of Environment and Tourism to study elephant movements, demography, ecology, behavior, and interactions with humans. My partner, Tim, and I were stationed in the Caprivi region of Namibia. This "day job" allowed us to spend our winters in Etosha, where Tim would analyze the movement data he collected from nine elephants fitted with satellite and radio collars while I would have the luxury of focusing solely on elephant communication and behavior. I hoped to use that research to help farmers in the Caprivi to prevent elephants from raiding their crops, which sometimes amounted to a whole year's worth of food consumed in one fell swoop.

It was during these off-seasons of my initial three-year contract that I was able to spend countless hours by myself watching elephants at Mushara waterhole. I spent most of my time in the hide, a 10-foot-square cement bunker 33 feet from the water, with about 7 feet of its height buried in the ground and a pillbox slit facing the waterhole. It afforded a splendid view of elephants at close range but was very limited in terms of an overall picture of the negotiations made around the perimeter as to which herd was going to enter the clearing and when. But it allowed me to be closer to the action, and it was safe from lions or even a curious bull wanting to investigate the back of the truck. Once inside, however, I was committed for the night. It was me and my empty peanut butter jar, a makeshift but highly valued chamber pot in the bush.

I stayed in the dank bunker for as long as physically possible, usually about a week at a time. The isolation allowed me to reflect on the elephants' natural rhythms and to notice many behavioral patterns that had never been previously documented. These patterns formed the basis of my thinking for the next fifteen years of my career as a scientist. Eventually, once I learned to slow my own sense of time, adapting it to the deliberate, meditative pace of an elephant, I started to understand the patterns I had been observing.

Occasionally, Broken Ear would turn herself in a particular direction and freeze, sometimes with ears flat against her head and sometimes with ears held out, looking like a satellite dish, scanning the horizon. As she scanned, she seemed to cue the other adults to follow her lead. When she alerted the others to pay attention, they all oriented in the same direction, froze again, sometimes with ears flat, leaning forward, one front foot propped up on the toenails. Other times, they extended their ears, sometimes keeping toenail contact with the ground, sometimes lifting one front foot completely off the ground, swinging it front to back. It's not surprising that the matriarch would be wary at the waterhole and that she would be using her ears to try to detect any unusual sound, but what were these elephants doing with their feet?

I scanned the horizon and saw a large bull heading in on the southwest elephant trail, about a half mile away, ears fanning as he lumbered along. The vigilant cows shifted positions, several of them facing in the direction of the incoming bull. But their ears were not outstretched in a listening position. Could they have sensed his approach through the ground?

I became very familiar with this particular way that elephants seemed to be listening with their feet. My curiosity grew as I watched an elephant assume a position with its ears flat against its head, occasionally accompanied by leaning, with a foot lift or toenail contact. It was known that these animals used their ears like a parabola, scanning back and forth while remaining still to listen to low-frequency sounds from other distant elephants, but I had never read any studies describing an elephant's ears positioned flat against its head while freezing and listening.

Other scientists had thought that the leaning behavior was a resting position and foot swinging an act of indecisiveness. This is probably the case some of the time, but there were also some times where it appeared as if the elephants were actually using their feet to sense something in the ground. After seeing these behaviors, I would notice the arrival of a new herd or a lone bull or an approaching vehicle. When more than one elephant engaged in this freezing/leaning/shifting at the same time, it seemed as if the whole herd were using their feet to detect a signal.

I knew about the process of listening through limbs, which is found elsewhere in the natural world. Before signing on with the Namibian government, I had studied this phenomenon -- known scientifically as seismic communication -- in insects. In a sense, I was only going from the very small to the very large, having spent endless hours in a small soundproof chamber recording the seismic love songs of a unique group of Hawaiian planthoppers. It may be hard to understand my fascination, but I observed some extraordinary behaviors occurring on a little koa twig rigged to a gramophone stylus -- behaviors that seemed very similar to those of these elephants.

When I would play the female planthopper's seismic call through the twig, the male would immediately press its weight down and would sometimes even lift up a leg or two, then inch forward, responding with its own seismic call, then freeze again, "listening" and perhaps attempting to locate the dummy female. I never could have imagined it sitting in that booth, but these little planthoppers and their extraordinary songs handed me a hypothesis for elephants that was so unexpected and controversial, I found myself occupied with the challenge of proving it over the course of the next decade.

Since many other species are known to transmit their vocalizations either through the ground or some surface such as a plant, it was not a completely ridiculous proposition that elephants might do the same. Many scholars have described how insects and other arthropods communicate by striking the ground or by coupling their vocalizations with a substrate. Other more complex animals such as fish, amphibians, lizards, snakes, and even crocodiles exploit this form of communication, too. However, the only mammals in which the mechanism has been well documented are small rodents such as the blind mole rat, the kangaroo rat, and the golden mole (though there is evidence that elephant seals may also share this skill).

Seismic communication may sound complicated, but it simply means a sound wave used for communication that travels within the surface of the ground as opposed to the air. Although it seems stiff, the earth is actually elastic. Tossing a stone across its surface, for example, would cause it to ripple, just like the surface of water. These surface ripples can be imagined on a larger scale such as in the case of earthquakes.

On a much smaller scale, surface waves from the slightest bouncing up and down of a hungry spider at the edge of her trap become a dinner bell. Similarly, a plant stem supports the same types of waves for a lonely planthopper looking for a mate. I discovered that the earth also acts as a sounding board for the elephant. But I knew it was going to be difficult to be certain and then convince others in my field that a large terrestrial mammal might be communicating seismically.

The concept isn't all that different from a person putting an ear to the railroad tracks to listen for a distant train, literally keeping an ear to the ground. It was illustrated in the movie Dances with Wolves when Kevin Costner listened to the ground to feel the tremors from a stampede of distant tatonka or American bison, a technique used by Native Americans to prepare for a hunt. Or, for Lord of the Rings fans, Aragorn putting his head to the rock to listen for the distant thumping feet of the fearsome Urukai as they bore Merry and Pippin away to Isengard.

A student of a Native American tracker once told me that in order to feel the pressure waves from the heartbeats of their enemies, the Apaches would hold the hairs on the backs of their fingers up to the windows of their enemies' houses. That's pretty subtle stuff. However, maybe it is not so subtle a sense for those who have a real use for it. There are institutes for the hearing impaired, for example, with special wooden dance floors designed to facilitate the hearing of music through feet.

Since all primates have the ability to detect vibrations through specially adapted pressure receptors in the hands, feet, and lips, among other places, it's not at all surprising that we have the ability to detect vibrations. If we really paid attention, or perhaps if those vibrations were a more important source of our long-distance communication, we would doubtlessly be able to detect vibrations much more acutely. In a quieter era, low-frequency drums or instruments like the didgeridoo might very well have been an important means for sending a message to a distant receiver through the ground. For those who need this communication channel, such as the hearing impaired, the area of the brain that processes touch, the somatosensory cortex, can even take over the function of the auditory cortex, providing that much more area dedicated to vibration detection.

For the elephants in the wild, I was beginning to think that perhaps seismic signals played an important role in their complex communication repertoire. Perhaps they, too, had honed their skills at detecting vibrations to better interpret their world.

The looming bull came and went. He was old and in musth, with all the telltale signs of this hormonal state: a sappy secretion streamed from his temporal glands and he dribbled urine, which left a sheen of crusty green algae around his penis sheath. He did the rounds, searching for an estrus female. With each, he would test the cow's vulva with his trunk, inspect any urine patch in the sand, and roll his trunk tip to the back of his mouth to reach the duct leading to the vomeronasal organ, a special hormone-sensing structure that let him know if a female was in heat. With mouth wide open, he looked like a dirty old man, testing the tannins of the progesterone equivalent of red wine with his flehmen grimace. Nothing smelled interesting, so he sauntered off.

At this point, Broken Ear also decided it was time to leave. She stopped drinking and stepped away from the waterhole. She oriented toward her destination, emitted one long, low rumble, and waited there. Although two others rumbled in response, nobody appeared to make a move, and after standing still for about thirty seconds, she repeated her "let's go" rumble. After several of these rumbles, a few of the other cows finally decided to address this call to action and slowly lined up behind her. The group then meandered off to another foraging spot.

I watched Broken Ear and her family disappear into the tree line and then returned to my packing, occasionally scanning the horizon for possible new visitors. After coiling some wires and packing up my camera equipment, I watched a dust devil on the horizon and tried to decide whether it was going to blow through camp. While my eyes followed its course, I suddenly caught sight of a chalky gray mass lurking in the bush just beyond the waterhole clearing.

It was a new herd, consisting of a young matriarch and most likely her two younger sisters and their calves. They stood there for the better part of an hour, smelling the air with their trunks held high, mouths agape with anxiety, pitting thirst against caution. Could she have been waiting for Broken Ear to leave? I hadn't noticed that Broken Ear was not amenable to sharing her waterhole visits. Except for Collar, so named because she wore a satellite and radio collar as part of a movement study conducted by park researchers, elephants in this remote region of the park seemed to be accustomed to sharing their waterhole visits with at least one other herd. It was clear that no elephant wanted to contest Collar's challenges, not even by sneaking around to the overflow of the well that formed a flat pan of water.

Collar spent many of her visits simply holding off other elephants so that her family could have sole access to the water. Because of her tenacity, I often wondered how she managed to get enough to drink. And what had happened to her that she would view sharing as a threat when other herds appeared to have adapted to the routine? Another collared elephant in my more recent studies displayed similar behavior and became known as the "Collared Bitch" by my colleagues, who were most entertained by her defensiveness. Eventually, I decided that she needed a kinder name and began to call her Margaret Thatcher. It appeared that she was simply acting in the best interests of her family.

Seeing this new herd's reluctance to approach the water with a strange vehicle parked near the edge, I began to think that perhaps I was the cause for concern. At this point at the end of winter, most elephants in this lonely eastern region of the park would have seen the truck at some time during the season. Maybe these were stragglers from the west where all the natural pans had dried up.

They continued to wave their trunks high in the air as they stood in a tight cluster. I was upwind of them. An elephant, knowing the scent of humans, must have smelled me but probably did not see me. Otherwise, the matriarch would have shaken her head at me, objecting to my presence by flapping her large ears to make a loud cracking sound.

The herd finally got the courage to break out into the open in a hurried, stiff-bodied cluster, calves under bellies. A lingering dust plume hung in the still air behind them. Once they arrived at the waterhole, they spread out, rinsed the dust from their trunks with a scoop of water skimmed from the surface, and sprayed it out in front of them before starting to drink. It must have been a long time since they had had any water.

They were an unusually small group for this region of the park. The matriarch was relatively young, probably in her late twenties, judging by her overall appearance, height, skin condition, and the quality of her ears. Elephants are born with wrinkly skin and get even more wrinkled as they age. Their skin thins and gets more delicate, their hips and shoulders tend to show more, the temporal region just under their forehead sinks in, and some of the older cows even appear to grow longer rather than taller. Their ears get more frayed at the edges, some with large holes or slits. Some older matriarchs even have a "broken" or bent ear, where the cartilage at the top gets damaged over the course of up to sixty years of long-distance travels.

Although tusks are often used by researchers to identify individuals, they were a difficult characteristic in Etosha to count on, because a mineral deficiency in the soil caused them to break easily. None of the elephants there had very impressive tusks. Still, shape was helpful, particularly if one was missing or was unusually long or splayed.

As the afternoon began to slip away, I no longer had the energy for the tedious task of unearthing the buried microphone cables, packing up the rest of my gear, and getting ready to leave. Besides, I didn't like to be out walking around the waterhole alone in the late afternoon with so many lions in the area. Nor did I want to drive in the dark unless I absolutely had to. So it wasn't hard to convince myself to spend one more night at the site with the ever-enticing thought that another recording session would be the best yet.

It was an affliction of the occupation, wanting to record just one more breeding herd's vocal interaction as the elephants left the waterhole, or an aggressive encounter between a breeding herd and a rhino, or a lion roar, or an aggressive bout between two male rhinos. Perhaps this was the night that the hyenas would hunt down a kudu, loping around the waterhole with their demonic giggling after the terrified young buck. Or, if I was especially lucky, I might even record an elephant warning call that I could test out in the Caprivi farmers' fields to see if it would scare off crop-raiders. I had come to love recording the sounds of the African night, so it didn't take much convincing.

Often there was a sign just before something worth recording took place. If a jackal stumbled upon a lion, for example, it would rend the night with a sharp staccato barking that was very different from the normal undulating howls that jackals made in chorus. It was almost as if they were barking, "Lion! Lion! Lion! Ra, ra, ra. Lion! Lion! Lion!" Or, if you were vigilant and the lion was close by, you could hear a soft moan just before the lion initiated a full roaring session. There was enough of a gap between this noise and the real vocalization that I was usually able to turn the recorder on in time to capture a complete sequence of roars.

Having decided to stay, I turned my attention back to the waterhole. When the young matriarch began to leave, she stepped away from the water and rumbled softly. There was a return rumble and then another. From previous observations, I found that the time between the initiation of a "let's go" rumble and actual departure seemed to vary from moments to up to a half hour, depending on the herd's motivation level given a particular situation and what could only be attributed to the authority of the matriarch. This one was obviously more effective than Broken Ear at rallying the troops by getting a reply and a reaction so quickly. The rest of the herd reluctantly lined up behind her and slowly moved off in patchy single file, disappearing into the bush at the edge of the clearing.

The coordinated vocalizations that occurred during departure from a waterhole were very well synchronized, with little or no gap between them, as if the elephants were trying to create a single, continuous repeated call. I always took careful notes on these interactive calls during departure because I thought they might have some significance. Were the elephants specifically trying to create a longer signal, one that might be more easily detectable over long distances? And would it also facilitate better reception through the ground?

After this group left, I sat in the quiet late afternoon light, enjoying the stillness of the air and the waterhole with no animals present. I knew it wouldn't last though, so I didn't let myself linger too long before preparing for nightfall.

I packed up the back of my truck and prepared to descend into my nighttime recording station and sleeping quarters. While I was in the middle of settling in, two middle-aged bulls meandered in from opposite directions, both looking like they had come up from the southwest of the park. Elephants from that area were always easily identified because they were covered in a powdery white calcrete and looked like ghosts rising up from the horizon. Another sign that the season was changing -- the eles were on the move.

Because bulls typically spend a great deal of time at the waterhole, I had to make sure that I had finished preparing everything I could before they arrived or else I would be stuck for hours without my recording equipment. As these two approached, they saw me walking to and from the vehicle. I purposefully stood outside the hide until they reached the edge of the water. I wanted them to feel comfortable with my presence so that I could continue to finish burying the wires behind the hide. Since I wasn't observing bull interactions at the time, I wasn't worried about my effect on their behavior.

I was slowly recognizing a few of the bulls and started to feel like they were my custodians, their presence providing me with protection against the unknown in the darkness of the night. These silent giants became a great solace to me, particularly the older ones and one very distinctive-looking one with huge wide-splayed tusks and a gentle manner. I wasn't alone here. Even when I lay awake at 2:00 A.M. listening to their slow and contemplative drinking, I felt like somehow we were keeping each other company, like they knew I was awake, listening. And although I had never read about bulls emitting vocalizations in the context of leaving, sure enough, often when a few old bulls left the water at night, they made a long, low rumble, one starting the chorus and another ending it, as if to say goodbye to their mysterious companion, though I knew full well they were talking to each other.

The bulls usually released some flatulence prior to the rumble, so the "let's go" included a high-pitched clapping sound before the very low rumble, probably because of the energy required to emit this powerful low-frequency call. These bulls would emit several rumbles while heading off into the bush to spend the rest of the wee hours dozing and foraging. Or sometimes a single bull would call repeatedly into the silence, and sure enough, a herd would arrive at the waterhole a short while later. It was as if he were signaling that the coast was clear, or perhaps it was a musth rumble but at the time, I didn't really know the true nature of this call, just that it was correlated with the arrival of a family.

The bulls tolerated my presence, as long as I kept to the far side of the hide, but I moved more carefully now, knowing that at any moment they could decide to be less gracious about sharing their space with me. The bull elephant is the most powerful animal in the bush, the true king of the jungle. I wanted to foster the benevolent dictator side of the beasts, as I knew that a tyrant could lie dormant just below the surface.

After I finished setting up and closed myself into the hide, the bulls decided to leave. It was as if they were entertained by my presence and now the show was over. Before going, however, they slowly approached, sniffing around the narrow pillbox slit, and along the sand I had shoveled over the wires. In general, they were only this curious during my first visits to the site or if they sensed that something was different, like when I had to reconfigure my setup or leave the site. Any other time, they usually ignored me.

One bull inspected the rock cairn that protected my microphone while the other stuck his trunk just inside the slit to smell me. He was very tentative, not wanting to risk damage to his trunk. Inches away from me, two hairy, dripping lips hovered inquisitively and sniffed heavily, scanning back and forth like an alien in a B horror movie. I held my flashlight tightly, prepared to tap the prehensile periscope away if necessary.

I often felt that if I did not allow them to explore the equipment, they would become resentful of this intrusion on their space and take it out on the microphone. I was only a guest at their bar and bathhouse, after all. Perhaps an anthropomorphic sentiment for a scientist, but it seemed like the appropriate thing to do, and so far it worked. Sure enough, after satisfying their curiosity, the bulls sauntered off.

Eventually, more elephants arrived, this time the very large extended family led by Left Tusker. They approached the waterhole boldly, parading into the arena bathed in the peachy pink splendor of the setting sun. There were thirty-five individuals in this herd, most likely two bond units made up of several families, including a tiny baby that did not yet have control of its trunk. They all hurriedly lined up to drink, except for the little one, which swung its head, trying to get momentum into its dangling, flaccid appendage. Futilely trying to imitate the others in the dexterous use of their trunks, the little one seemed confused that this thing would do nothing but swing uselessly in front of its face. Meanwhile, the mother kept a very close watch, tucking the baby under her belly every time it tried to stray in the direction of a young cousin.

An elephant's trunk is an extraordinary organ, containing more than one hundred thousand muscles, giving it remarkable agility. The San, or bushmen, with whom we worked in the Caprivi call the trunk a hand, because it is so precise in its movements and its ability to grasp. However, this little one's "hand" was effectively a lifeless, hanging arm, paralyzed from the elbow down; the ability to control its limb would develop in another month or so. In the meantime, the baby kept pushing it forward by moving its head forward, causing a pendulum effect down the length of the trunk. In frustration, it would then start swinging the trunk in circles, whacking itself with its limp propeller.

It suckled a while with trunk hanging to the side, just next to its mother's front knee. (A nursing elephant is an incongruous sight because the mother's teats are located in the chest area. It always reminds me of the elephant's close relative, the dugong, whose head and voluptuous chest poking up through the long sea grass led to the tales of mermaids.) The baby then dropped to its knees, trying to reach the water by bouncing its head up and down to get its yo-yo to touch the surface. The poor thing finally reached just a little too far and kurplunk -- it fell like a rock into the trough, surfacing with a shockingly bloodcurdling scream.

The screaming engaged the emergency excavation crew, where aunts and sisters probed at the trough with stiff trunks, trying to scoop out the thrashing baby, while mother held the rubbernecking crowd of youngsters at bay. They eventually fished the baby out, and it stood soaking wet, sulking under its mother's belly.

Perhaps because of the baby, the herd was very anxious and wouldn't settle down after the unexpected dip. Herds are always especially wary when a new baby arrives, as it is particularly vulnerable to lion attacks. Once, in the Caprivi, we witnessed the aftermath of lions isolating a young bull out on the open floodplain in front of our hut. He had strayed just far enough from the herd to be in peril and paid the price that day with his life.

Most young bulls seemed to know the exact distance where they could feel safe from danger yet separated enough from the herd to seem liberated. This was especially evident when watching the arrival or departure of a herd at a waterhole. A preadolescent bull would often parade out in front and be the first to arrive at the water, sometimes demonstrating his dominance to the rest of the animal kingdom by chasing off all the other animals, even if only a flock of guinea fowl. He was also the last to leave, lagging just far enough behind to seem independent. But if he pushed it too far, he generally realized the error of his ways and panicked, running, trumpeting, and bellowing off after his family. Back in the security of the herd, he tucked in quietly, looking almost embarrassed, as if he had nothing to do with the previous scene. Herds seemed so familiar with this routine that they appeared unfazed by these riotous outbursts.

Once elephant bulls reach about age twelve, however, the matriarch and the other adult cows lose patience with these antics and unsolicited sexual advances. They kick the adolescent males out of the herd, where they are forced to develop new relationships with other bulls or roam on their own with other occasional companions. It was always clear who the dominant bulls were in these bachelor groups by the response of the other bulls at the waterhole. Upon their arrival, all the others would step backward some distance, clearing the way for the dominant male to have room at the head of the outflow, the freshest water. Once he got into position, the younger males would take their turn approaching him, placing their trunk in his mouth before repositioning themselves down the line. It was like watching mafiosi paying respects to the don. The older bulls, however, would just look on and drink, as if to pay their respects with a nod rather than the more supplicating action of the trunk greeting.

By the time the younger males are old enough to enter into the bull society, they are usually too big for lions to contend with unless they are sick. It's difficult to imagine that lions could penetrate a whole herd of breeding elephants to get to a baby, but at the end of my last field season at Mushara, we saw the possible remains of exactly that. Tim drove up from Okaukuejo late in the morning to help me pack up my site, and just as we were leaving, a young cow approached the water with something dangling between her legs. We watched as she waded into the water to wash herself, swinging her front leg back and forth between her hind legs to flush out the placenta. Her brow was wrinkled and her eyes turned down as if in great distress. If her baby was alive, there was no way she would have left it behind.

After washing herself, she slowly headed back into the bush. We tried to follow her, far enough behind so as not to upset her, but then the bush got too thick and we eventually gave up. We wanted to solve the mystery. Was she heading back to her dead baby? Did she fall behind the herd while giving birth and the baby was taken by lions? We would never know, although it wasn't normal for a herd to leave a birthing mother alone. Usually, the whole family made a circle around the mother and waited for the baby to be born; and a baby elephant is born to run, so there isn't much waiting around afterward.

The elephant herd at the waterhole was now radiant and almost cartoon pink in the light of the setting sun. But they were agitated. In fact, I had never seen a herd so nervous. I had settled into the bunker for the night and couldn't see behind me, so I couldn't tell what was upsetting them, but there was clearly something.

My suspicions were confirmed. A small herd of gemsbok (oryx) reached the edge of the clearing and remained there, stamping their feet and snorting in objection to something in the bush behind me. I wanted to lift the heavy iron hatch of the bunker to check, but it would have made too much noise and I did not want to scare the elephants. I set up my video camera on a tripod and let it run.

Finally, seemingly out of nowhere, the matriarch bellowed. It was a deep, low, urgent rumble, the most impressive call I had recorded to date. After three such calls, she turned and fled, leaving the rest of the herd screaming and trumpeting behind her, the little ones trying to keep up, tails straight out, trunks flying. Not much of a coordinated departure this time.

Several minutes later, they reached the edge of the clearing, and then the waterhole went silent again. The twilight filtered through the thick cloud of dust hovering about a meter above the ground. I sat there in awe, waiting for an explanation. The pan was now a brilliant red, too dark to film, so I turned off the video but left the tape recorder running.

Meanwhile, a covey of double-banded sand grouse trickled in and filled the edge of the flat pan, the spillover from the trough, stashing precious droplets in their feathers to take back to their nests. I sat and took in the still but melodious scene as more and more grouse spilled in. There was something else out there. The feeling was palpable.

If you are very focused, you can sometimes smell lion. It's a kind of thick, leathery smell, similar to a buffalo but more musty. I don't know whether I wanted to smell them or whether I really did, but I knew there must have been some lions sitting at the edge of the clearing behind me. I waited for something to happen as the grouse had their fill and left behind an unsettling silence.

The answer to the mystery was soon revealed with an overpowering roar that pounded on my chest and quickened my heart with each bellow. Then came a reply from the adjacent corner, and then a volley of heaving roars as the two cats approached the water. I got out our government-issue Zeiss low-light binoculars and scanned the area, waiting, frozen in my stance, marveling at how assaulted I felt by the tremendous pressure waves of their roars. The chorus crescendoed. I knew I would get a fantastic recording.

Suddenly there was silence again. Then I heard the telltale sign of a large predator at the waterhole: the slow beating of a weighty tongue as it laps at the surface of the water. I heard it off in the distance, and then there was another, even closer lapping. Finally, I could see them: two young males sporting barely respectable manes, but they were very large, and they meant business. I settled in, excited at the prospect of the amazing recording I would capture from this potentially active night. But eventually, overcome with the exhaustion of waiting, I passed out.

I awoke early the next morning to the sounds of vultures bickering at the waterhole. Groggy and stiff, I shielded my eyes from the blinding light of the outside world and peered through the slit. It was a gruesome sight. Vultures lined the water's edge, sticky with blood; more were perched in a tree at the edge of the clearing, and two marabou storks adorned an adjacent tree. There was not another animal in sight.

I climbed up the ladder of the bunker and carefully slid open the heavy manhole cover so as not to upset the resident geckos. Standing on top, scanning the clearing with my binoculars, I could see more vultures directly behind me. No sign of the lions but the remains of their dinner, a young male gemsbok, was plainly visible. At this point, the only thing left to identify him were his horns and the black and white socks still left on his ankles. The rest was bone.

Knowing that the lions must still be in the vicinity -- they wouldn't stray far from a kill or the water -- I did not want to pull in the wiring from the waterhole without the truck, so I started to pack up the other equipment. I carried a big stick as I walked over to the truck to bring it closer to the hide. Since I had not expected to stay another night, I hadn't charged all of my recorder batteries the day before and had to tap into the truck battery to record the lion roars. One turn of the ignition made it clear that the battery was dead. I took the solar panel out of the back of the truck, placed it at an angle on the hood using a rock, and attached the battery. Judging from the sound of the alternator, it would take a few hours to charge.

While waiting, I pulled up the wiring between the hide and the truck, keeping careful watch for the lions. They were probably resting their gorged stomachs in the shade at the edge of the clearing somewhere, so I took comfort in knowing that they wouldn't want to bother with me in that condition. I still kept an eye out as I packed up the rest of the equipment.

When the battery was fully charged, I put the last few bags into the back of the truck and the recording equipment in the front. I jotted down some last notes on recording improvements I could make for the following season. I wanted to see if the low-frequency, high-amplitude acoustic rumbles that elephants made were capable of moving through the ground as well, which might explain the curious behaviors I had been documenting.

I had a lot to learn about recording sound in the ground. I knew that seismologists used a geophone to measure earthquakes, which worked pretty much like a condenser microphone with a magnet and coil. The movement of the earth moved the magnet and coil, which generated a voltage that scaled with the strength of the signal. But how many geophones would I need and how expensive were they? And how would I amplify the signal? With very little access to lines of communication with the United States, it was going to be all the more difficult to develop a discourse with potential colleagues in a field about which I knew very little. I could see Mount Everest standing in front of me, but I was still excited about the possibilities.

I said my good-byes to Mushara and headed north, back to the Caprivi. It was a long eight-hour stretch with not much distraction to stay awake, other than the sudden shock of a herd of cattle sitting in the middle of the road while barreling toward them at 75 mph or a lone kudu leaping out in front of the truck. Needless to say, it was much safer to travel the country by daylight than by night, but that wasn't always possible.

And yet the eight hours was barely enough to transition from my solitude in the semidesert expanses of Etosha to the green and lush but tumultuous Caprivi. Our supervisor, Jo Tagg, liked to call the Caprivi "God's Country." And yet he'd say that survival there required "honing one's ironic distance," essentially meaning that you needed to get good at not letting anything affect you at any level.

The Caprivi had been a war zone not just between humans but between humans and nature, and farmers were pitted against the elephant in a battle for survival. The tragedy was that its striking beauty went unrecognized by those who could make a difference and was voraciously consumed by the rest.

Copyright © 2007 by Caitlin O'Connell

Continues...

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Excerpted from The Elephant's Secret Sense by Caitlin O'Connell Copyright © 2007 by Caitlin O'Connell. Excerpted by permission.
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