Elephants Alert Group to Human Presence with Unique Alarm Call [VIDEO]

Elephants trumpet a low, rumbling alarm call specifically when they detect approaching humans, according to new research from wildlife biologists working in Africa.

Working in northern Kenya, the research team studied a herd of wild elephants and how they reacted to the voices of approaching Samburu tribesmen, a local population. When a group of resting elephants were played a recording of the voices of the Samburu people, the the elephants reacted quickly, becoming vigilant and running away from the sound while making a low, rumbling noise. (Click here to watch a video of the elephants reacting and hear audio of the alarm call.)

After obtaining a recording of this low-pitched alarm call, the researchers played it back to a group of elephants and observed their reaction, which was similar to how they reacted to the recording of human voices. Some of the elephants even appeared to search for the threat indicated by the warning call, an act of vigilance the researchers said was remarkable.

Writing in the open-access journal PLOS One, Lucy King, a wildlife biologist with University of Oxford and the Save the Elephants non-profit, along with Joseph Soltis, a bioacoustics expert from Disney's Animal Kingdom and colleagues, report that elephants seeming to have a human-specific alarm call is similar to other evidence that elephants have a unique way of identifying and communicating the threat of killer bees.

"We concede the possibility that these alarm calls are simply a by-product of elephants running away, that is, just an emotional response to the threat that other elephants pick up on," King said in a news release from Oxford University.

"On the other hand, we think it is also possible that the rumble alarms are akin to words in human language, and that elephants voluntarily and purposefully make those alarm calls to warn others about specific threats," she said. "Our research results here show that African elephant alarm calls can differentiate between two types of threat and reflect the level of urgency of that threat."

The researchers pointed out that the human-threat alarm involved none of the head-shaking that was observed in elephants using their bee alarm, which the biologists say is significant because it shows there is a differentiation between the alarms.

King said that difference is pitch is equivalent to a change in vowel sounds in English words, such as the distinction between sounds of "boo" versus "bee."

"Elephants use similar vowel-like changes in their rumbles to differentiate the type of threat they experience, and so give specific warnings to other elephants who can decipher the sounds," she said.

Knowing more about what elephants are afraid can be used for conversation efforts, the researchers said. For instance, bee hives can be placed around cropland and other agricultural areas in an effort to keep elephants away.

"In this way, local farmers can protect their families and livelihoods without direct conflict with elephants, and they can harvest the honey too for extra income," King said. "Learning more about how elephants react to threats such as bees and humans will help us design strategies to reduce human-elephant conflict and protect people and elephants."