Elephants learn to imitate sounds that are not typical of their species, the first known example after humans of vocal learning in a non-primate terrestrial mammal. The discovery, reported in today's Nature, further supports the idea that vocal learning is important for maintaining individual social relationships among animals that separate and reunite over time, like dolphins and whales, some birds, and bats.
Researchers from the Amboseli Trust for Elephants in Kenya, the Woods Hole Oceanographic Institution and the University of Vienna studied sounds made by two African elephants, one living among semi-captive orphaned elephants and the other with two Asian elephants in a zoo. One imitated truck noises heard from a nearby highway, the other the chirps of another elephant species.
In both cases, the sounds were totally different from sounds made by other normal calf, adolescent and adult African elephants and very similar to recorded sounds that were common in the auditory environment of the subjects of this study. Spectrogram analyses of the audio frequency of the imitations were nearly perfect matches to the original sounds.
Mlaika, a ten-year-old adolescent female African elephant living in Kenya among a group of semi-captive orphans, mimicked noises she heard from trucks on a highway nearly two miles away. Her imitations of the trucks sounded much like recorded truck sounds and nothing like normal calls of African elephants. Mlaika did not appear to imitate particular trucks as she was hearing them, but rather seemed to use generalized truck sounds as the model for her imitation.
Calimero, a 23-year-old male African elephant who lived for 18 years with two female Asian elephants in a Swiss zoo, was a nearly perfect mimic for the chirp-like calls of his long-time zoo mates. The chirps are made by Asian elephants but not by African elephants. Calimero often mimicked the chirps but rarely made any other sounds.
"Many species with similar social systems as elephants use vocal imitation to maintain individual-specific relationships, "study co-author Stephanie Watwood of WHOI said. "Our study suggests that elephants may be using their vocal learning abilities in a similar manner, and opens a fascinating new area for research on how elephants use vocal learning."
Vocal learning is important because it enables an open communication system in which animals and humans develop new signals with shared associations. Recent playback experiments conducted by Karen McComb of Sussex University have shown that elephants can remember the calls of a large number of other elephants. The new findings suggest that elephants, like parrots, bats, and dolphins, may use vocal learning to develop new communication signals for maintaining complex individual-specific social relationships, study co-author Peter Tyack of WHOI said. Tyack has studied the social behavior and acoustics signals of marine mammals, especially dolphins and whales, for decades.
"It is exciting to see that African savannah elephants follow a pattern we've seen in other terrestrial and aquatic species capable of vocal learning, "Tyack said. "Vocal learning should also occur in other species where long-lived social bonds are based on individual relationships and where members of a group separate and reunite over time."
The study was funded by the Woods Hole Oceanographic Institution.
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