A DEVICE used to track enemy troop movements during the Vietnam war may give conservationists a better understanding of elephant behaviour.
Forest elephants, thought to be a different species from their kin on Africa鈥檚 savannahs, have been difficult to count because dense tree cover hides them from aerial surveys. Until now, the best estimates have come from counting dung balls, but this is labour-intensive and error-prone.
Jason Wood and his colleagues at Stanford University in California instead tried using a small seismic detector, or geophone, to track the rumble of elephant footfalls. The researchers buried a geophone near a waterhole in Etosha National Park in Namibia and recorded animals as they passed. When they analysed the recordings, they found they could distinguish elephant footsteps from those of other large mammals by a stronger low-frequency component to the rumble. They were also able to estimate the number of animals in a group from the total energy generated by their footfalls (Journal of Applied Ecology, vol 42, p 587).
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Geophones cost several thousand dollars each, so the systems will be expensive to implement. But Wood hopes they will reveal unprecedented details about the timing of elephant activity over days or months. 鈥淚t gives you a different insight into what that population is doing,鈥� he says.
