East Africa’s elephants face few threats in their savanna home, aside from humans and lions. But the behemoths are terrified of African bees, and with good reason. An angry swarm can sting elephants around their eyes and inside their trunks and pierce the skin of young calves. Now, a new study shows that the pachyderms utter a distinctive rumble in response to the sound of bees, the first time an alarm call has been identified in elephants.
“It’s an important finding,” says Karen McComb a behavioral ecologist at the University of Sussex in the United Kingdom. “It not only provides the first demonstration that elephants use alarm calls but also shows that these may have very specific meanings.” Indeed, the study suggests that this alarm call isn’t just a generalized vocalization but means specifically, “Bees!” says Lucy King, a postgraduate zoologist at the University of Oxford in the United Kingdom and the study’s lead author.
Several other species, including primates and birds, make calls that warn others of danger. Because elephants also have an extensive repertoire of vocalizations, researchers have long suspected that certain calls have specific meanings. But it’s not easy for researchers to link the pachyderms’ calls—many of which are beyond the range of human hearing—to particular events. A few years ago, however, King and colleagues documented the fear elephants have of bees via a series of playback experiments: When they hear buzzing bees, the pachyderms turn and run away, shaking their heads while making a call that King terms the “bee rumble."
To find out if the bee rumble is an alarm call, King's team played the vocalization to 10 elephant families. Six of the herds fled, even though they had neither seen nor heard bees. In contrast, only two families moved away when the scientists played another rumble that lacked a key acoustical feature that they had identified in the bee rumbles, the team reports today in PLoS One.
It may be that elephants can subtly alter a call, simply by changing the position of their lips and tongues, just as humans do to produce different vowels, King says. If so, then elephants may also have warning calls to alert their fellows to humans and lions—much like Diana monkeys in West Africa can call out a leopard alarm or eagle alarm, depending on which predator they spot.
It will take further experiments to show that the bee rumble means bees to other elephants and is not a more general alarm call, says Robert Seyfarth, a biological anthropologist at the University of Pennsylvania. Nevertheless, he says, “the paper adds significantly to our knowledge of animal communication” because it adds elephants to a growing list of animals whose vocalizations are slowly being deciphered.