An elephant that makes truck sounds has researchers wondering if communication among these lumbering giants may be more sophisticated than they'd realized. The newly-demonstrated ability to imitate sounds earns elephants a place on the short list of animals capable of learning vocalizations.
Only a handful of animals are able to modify their calls based on their experience. Many male songbirds, for example, woo females using songs they learned as youths by imitating their fathers. Primates and marine mammals such as whales and dolphins are also vocal learners.
The first clue that elephants might be as well came from an adolescent female African elephant named Mlaika, who lives at a reserve in Tsavo, Kenya, says Joyce Poole, director of Elephant Voices, a research project headquartered in Norway. Poole visited Tsavo after hearing from colleagues that Mlaika was making strange sounds. Having studied elephant vocalizations for nearly 20 years, Poole expected that Mlaika's sounds would be something she'd heard before. Not so. "It was completely unelephantlike," she says. "It sounded like a foghorn or something."
It soon dawned on Poole that Mlaika's vocalizations resembled the sounds of trucks rolling down the nearby Nairobi-Mombassa highway. The truck sounds were sometimes audible from Mlaika's night stockade, and Mlaika only made the sound at night, Poole says. In the 24 March issue of Nature, she and colleagues present acoustic measurements showing that Mlaika's calls resemble recorded truck sounds far more than they do the calls of other African elephants. They report similar measurements for a male African elephant, Calimero, who lived with two Asian elephants at the Basel Zoo in Switzerland for 18 years. Calimero's chirp-like vocalizations resemble Asian elephant calls but are unlike any sounds normally made by African elephants. The authors say these are the first examples of vocal learning in a terrestrial mammal other than primates.
"The fact that elephants are capable of vocal imitation is extremely interesting because in mammals this is so rare," says Karen McComb, who studies mammal communication at the University of Sussex in the United Kingdom. She points out that studies of vocal learning in other species have suggested that individuals' calls become more similar as the animals form social bonds, which might help groups keep in touch or defend their turf. "There seems to be an advantage to being able to talk like your neighbors," she says. Whether elephants put their imitation skills to good use in the wild remains to be seen.