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The river is a maze of channel-ways and low islands and on almost every island a herd of elephants is feeding. On our way out to the nearest herd we passed a large group of water buffalo bedded down in the long grass. Except for the vicious hook of their jet-black horns they could have been a bunch of domestic cattle. "Don't let that fool you," said David, "they are mean and unpredictable." He was not the only one to caution us about approaching these wild bovines. They have a reputation for charging without warning or provocation.
David slid the skiff onto the muddy bank of an island only a stone's throw from where a group of elephants were feeding. They seemed oblivious to our presence until we crossed some invisible line that defined their space. If we got too close one of the largest in the group would turn and face us with ears spread and a stare that said "back off right now" and we didn't argue.
I counted 23 elephants on our island a mix of adults, juveniles and a few small calves and the groups on other islands appeared to be about the same size. Elephants are highly social, living in herds made up of a matriarch, her female offspring and their calves. In their early teens juvenile males leave the family herd and join groups of bachelor bulls. Females mature at about age 12, mate with the dominant bull from a bachelor group, and become the matriarchs of new family herds.
According to Wildlife Africa, each adult elephant consumes about 250 Kg (550 pounds) of food a day. As we watched them daintily plucking tufts of grass with their long flexible trunks and carefully shaking dirt from the roots before popping the morsel into their mouths I wondered how many hours it must take to pack in that amount of hay. In fact elephants eat almost continuously and just about any vegetable matter will do leaves, twigs, and bark as well as grass, reeds and roots. They start life with six sets of molars, but grinding up that volume of silage takes its toll. The last set is usually worn out after 50 or 60 years and, unable to feed, the animal dies of starvation.
As the sun dipped into a layer of clouds just above the horizon the herds abruptly stopped feeding and began making their way toward the river. It was as though someone had yelled "OK guys dinner's over, time to go home." In fact that may well have been what they were saying to one another as herd after herd left the islands and began wading ashore. We humans just can't hear them. The powerful infrasonic calls of elephants, their rumbles, grunts and purrs, are well below the threshold of human hearing. But recent research indicates that these low frequency sounds are how elephants talk to one another. Bioacoustic research by a Cornell group has discovered that elephants, like whales, can communicate over great distances and the same techniques and acoustic arrays used to study marine mammals are now being used to learn more about the language of elephants.