WSB study: The sound of female elephants could drive away crop-raiding males

Image: A wild elephant forages in Sri Lanka. Sri Lankan elephants frequently raid crops, leading to violent conflicts with farmers. ©Amanda Perez, Smithsonian’s National Zoo

When a bull elephant decides to eat a farmer’s crops, no puny human voice is likely to change its mind. But the voices of female elephants are a different matter, according to a recent study in the Wildlife Society Bulletin. When male Asian elephants (Elephas maximus) in Sri Lanka heard recordings of female family groups, they abandoned their food and fled into the jungle. The findings suggest that farmers could use recordings to protect their crops, reducing violent clashes between elephants and humans.

“The take-home message is that it’s possible to use these vocalizations to basically scare an elephant away from a food source,” said Evan Bittner, an animal scientist at the University of Melbourne and senior author of the study, who is also the director of a nonprofit called “A Future with Elephants.” “It’s another method you can use for humane reduction of human-elephant conflicts.”

Human-elephant conflicts are a growing problem, says Bittner. Rising human populations are forcing endangered Asian elephants into shrinking patches of habitat, and hungry elephants often venture into farms for food. An elephant can destroy an entire crop in a matter of minutes, wiping out the only source of food and income for poor Sri Lankan farmers. Each year in Sri Lanka, about 161 elephants and 60 humans die in conflicts with each other.

Most of the crop-raiding elephants are adult males. Females and juveniles live in family groups, and they typically control the best habitat in the center of the forest, says Bittner. The solitary males are driven to the edges, unable to compete with the powerful matriarchal herds.

Bittner and his colleagues wondered whether they could take advantage of elephants’ social structure and vocal communication to control crop-raiding males. To find out, they fed piles of sugar cane, bananas and palm fronds to 22 male elephants in a Sri Lankan national park. While the elephants were eating, the researchers played four sounds: a lone female elephant, a group of females trumpeting during a territorial dispute, a chainsaw, and a swarm of Sri Lankan hornets (Vespa affinis affinis). The sounds were played in random order, with five minutes’ break in between to see how the elephants would react.

As expected, the elephants didn’t flee from the chainsaw, and only one left when it heard a lone female. Most also ignored the hornets, although two apparently remembered past encounters with the stinging insects, reacting with “a real shaking of the head and flapping of the ears,” says Bittner. But of the 17 males that heard the trumpeting of a matriarchal group, only six stood fast. Eleven retreated, not returning even after the sound had stopped.

“They just decide it’s not worth getting injured or getting in an argument or a fight with that big group,” says Bittner. “They leave the food and quickly flee away into the forest.”

Elephants would probably learn to ignore any recording if they heard the same one over and over, says Bittner. The researchers plan to test elephants’ reactions to a wide range of sounds, including aggressive males in the rutting state known as “musth.” Eventually, they hope to build up a library of recordings that farmers could switch up as needed.

The recordings won’t be a panacea for human-elephant conflict, Bittner warns. At best, they will be one tool in a larger strategy. Nevertheless, the new study suggests that sounds such as trumpeting females could serve as a cheap, non-violent elephant repellent.