Researchers in Kenya used voice recordings.
Although elephants have been known throughout history for their impeccable memory, recent studies have shown that elephants are incredible listeners as well. African elephants that hear human voices can distinguish between different sexes, ages, and even ethnic groups, according to a new study published in the journal Proceedings of the National Academy of Sciences. Such keen ears are necessary when trying to survive in territory marked by human-elephant conflict. African elephants are the largest land animals on Earth and are considered a vulnerable species due to habitat loss and illegal hunting for their ivory tusks.
Researchers decided to play recordings of human voices for elephants at the Amboseli National Park in Kenya to see how they would respond. They heard voices from local Maasai men, a group that often herd cattle and come into conflict with elephants over access to water. Other voices were Kamba men (who are usually employees of the park), young boys and girls, and female Maasai speakers. The researchers then took a speaker, camouflaged it with a screen woven of palm fronds, and placed it about fifty metres away from where they expected wandering elephants to end up. All of them spoke the same phrase, “Look, look over there, a group of elephants is coming.”
When the elephants heard the male Maasai voices, they tended to gather together, smell the air with their trunks, and then move away. When they heard voices from the others, they did not move at all, or show any concerns.
“Their response to hearing Maasai men talking was to be alert, to move away, but not to run away in total fear,” Keith Lindsay said, who is a conservation biologist in the Amboseli Elephant Research Project.
The Kamba men speak a different language than the Maasai, so it is likely the elephants were picking up on the linguistic differences, rather than the underlying differences in their voices. However, the researchers thought of this as well, and remixed the voices to sound more like a women’s voice, but the animals were not fooled by it.
The project took two years to complete. They intentionally spaced out the sessions, so the elephants would not get used to the experiment.
When it comes to recognizing people, elephants may not be alone in this ability. Other research has suggested that wild bottlenose dolphins in Brazil have become so familiar with humans that they engage in cooperative hunting with artisanal fisherman.