Elephants Tell by Seismic Waves if You Are A Friend or Not

Elephants are not only the largest land mammals, but also the possessors of some amazing abilities, like that of infrasound communication over large areas.

We cannot hear them, but elephants located tens of kilometers away can.

In 2004, the behavioral ecologist Caitlin O'Connell-Rodwell of Stanford University in Palo Alto, California, found that African elephants can communicate between them from kilometers away through ground vibrations. Even if they produce the calls with their trunks, the sounds also go several kilometers along the surface of the ground, about the same distance as airborne sounds.

A new research shows that their communication system is even more complicated: elephants make the difference between good vibrations and bad in the case of low, rumbling alarm calls, focusing on the seismic waves made by known elephants while ignoring those of strangers.

O'Connell-Rodwell observed groups of Namibian elephants stopping, leaning forward onto their toes and pushing their trunks onto the ground, like a listening posture, many times before the arrival of another herd of elephants.

She discovered that wild elephants responded only to the ground vibrations, probably employing vibration-sensitive cells in their feet and trunks.

To see if the elephants know who's making the alarm calls, O'Connell-Rodwell recorded alarm calls shouted by elephants encountering lions in Kenya and Namibia. The alarm sounds were turned into seismic waves and played to Namibian elephants visiting a water hole. The elephants reacted quickly to the Namibian waves by freezing, huddling and leaving the area.

But in the case of the Kenyan calls, they seemed to detect them, as they sometimes paused and looked more alert, but the reaction was weak and in the case of synthesized sounds with similar frequency and duration, these were totally ignored.

O'Connell-Rodwell believes this is not a dialectal issue: the calls from the two distinct elephant populations were similar in frequency and duration.

"More likely, is that the elephants trust the calls from animals they know but not those of strangers." she said.

"That might help them avoid expending unnecessary energy responding to bogus calls." said behavioral ecologist Jan Randall of San Francisco State University in California, who investigates kangaroo rats that use foot drumming vibrations to communicate.