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.