By Rhys Blakely, The Times of London
Africa’s elephants are alive to sensations that will for ever elude humans. They can sniff out food from miles away and use sounds below the range of our ears for long-distance communication.
A study now highlights another way that they make sense of the world — by reading vibrations transmitted through the earth. Researchers have shed new light on how wild African elephants decipher seismic activity, finding that they flee when it is caused by humans.
Conservationists say that the results show how human activity, such as the construction of new roads and seismic blasting for oil exploration, is likely to affect elephant herds.
Dr Beth Mortimer, of the University of Oxford, who led the research, said: “What this study shows is that human-generated seismic vibrations are relevant to elephants — they respond to them and they associate them with risk.”
Mortimer and researchers from Save the Elephants created three types of seismic activity and watched how elephants reacted in the Samburu and Buffalo Springs national reserves in Kenya.
They used three recordings. One included the sounds of the animals going about their usual business. Another contained white noise generated by a computer, using frequencies that are typical of human activities. A third combined the human and elephant sounds.
The tracks were played using a speaker partly buried in the earth. From where the elephants were standing, roughly 20 metres away, there would have been virtually no sound waves, but they were able to sense the tiny tremors that travelled through the earth.
When the animals sensed the human seismic activity they froze and scanned the horizon. They then fled. By contrast, there was no reaction for the elephant recordings. The findings touch on one of the most mysterious aspects of elephant life.
It is thought that they use seismic signals to communicate over distances of several miles. One theory is that bones in their legs and body transmit vibrations to the inner ear. They are also thought to use pressure sensors in their feet known as pacinian corpuscles.
Chris Thouless, of Save the Elephants, said that their senses “may detect other elephants, distant thunderstorms, and noises of human activities at great distances . . . but man-made noises may overwhelm the more subtle signals from the natural world”.