In the fight against poachers, deforestation, and habitat loss, conservationists have to constantly think outside the box – how to monitor and track the animals, how to stop poachers. They are willing to use any technology at their disposal.
An interdisciplinary team of biologists and geophysicists from Oxford University have come up with a novel way to “eavesdrop” on elephants, that actually makes a lot of sense: Track them using earthquake technology.
Elephants are the world's largest land animal, and like other behemoths – the blue whale and the T. rex, for example – are suspected of using low-frequency sounds to communicate over long distances.
The team realized that by using seismic technology usually used to measure earthquakes, they could detect and listen to the creatures’ vibrations through the ground. Their study, published in Current Biology, claims their findings add to the theory that elephants actually communicate through these ground vibrations.
"We were surprised by the size of the forces acting on the ground that were generated by elephants when they vocalize," said Dr Beth Mortimer, who led the study and represented the biologists in the team, in a statement.
"We found that the forces generated through elephant calls were comparable to the forces generated by a fast elephant walk. This means that elephant calls can travel significant distances through the ground and, in favorable conditions, further than the distance that calls travel through the air."
Elephants trumpet for many reasons, to signal distress or even playfulness, but many experts believe their rumbling is a more efficient form of communication, especially when in flat open terrain with little to interfere with the sound. These rumbles wouldn’t be heard by the human ear, coming in at around 20 hertz – the lowest end of the average human range – but would certainly be felt.
The researchers placed geophones in the ground in Kenya's Samburu National Reserve. Based on their seismic readings, the team estimated the vibrations could be felt through the ground 6.4 kilometers (4 miles) away and are created deliberately to communicate with any other elephant in that range.
The team also picked up the sound of elephants stamping, which can be heard up to 3.6 kilometers (2 miles) away, their model suggests. Not surprising considering they likened the sound to a sledgehammer.
They think that detecting the vibrations of a "panic run", when a group of animals picks up speed probably due to distress, could be an indicator that poachers are in the area, and detecting the vibrations could work as an early warning system. This could help identify when and where poachers are operating and let researchers know exactly where elephant herds are.
