From rumbles and roars, to barks and trumpets, elephants are quite the vocally expressive animals with complex vocal learning capabilities. Like humans, elephants are constantly communicating to each other using sophisticated communication networks, intricate vocal systems, and varying call sounds. But what might be the source of this variability? How do animals like elephants learn to produce these unique sounds in such extraordinary ranges? These are pivotal questions that researchers like Angela Stoeger, Anton Baotic, and Gunnar Heilman set out to explore throughout their research on vocal creativity and elephant sound production.
The researchers began to investigate these questions with five wild-born African savanna elephants: Jabu, Morula, Sawu, Mogli, and Drumbo. Jawu and Morula were studied in the Living with Elephants Foundation in Botswana, while Sawu, Mogli, and Drumbo were studied at Dresden Zoo in Germany. Vocalization behaviors were studied by presenting the elephants with a reward of food for encouragement of this behavior, a technique called positive reinforcement. The elephants were trained with positive reinforcement including additional verbal praise and patting that the elephants associated with receiving food after vocalization behavior was completed. In addition to visual observations, the researchers recorded vocalization call frequencies with microphones and sound pressure maps. Jabu, Morula, Sawu, Mogli, and Drumbo produced unique variations of sounds, ranging anywhere from high frequency sound (HFS) squeaks to low frequency throbbing sounds.
Jabu would push air out of his trunk, contracting its central muscles to produce a deep throbbing sound. Morula would also produce throbbing sounds but differently, using a lower muscle in the trunk. Mogli and Drumbo would lift their enormous trunks and abruptly produce oral bursts, softly releasing air in similar ways. And remarkably, Sawu would tilt his trunk slightly, slightly close her nasal tubes, and blow out HFS, producing some of the highest pitched calls documented in African elephants. This and the lower HFS produced by Jabu and Morula were the first reported elephant behaviors produced through sucking air inward. What made each of these vocalizations remarkable was that they were each uniquely generated by the elephants through continuous positive reinforcement and social interactions. These were just a few of the 625 vocalizations recorded and mapped by researchers that the five elephants made over fifteen years. Jabu, Morula, Sawu, Mogli, and Drumbo learned to make distinctive sounds in distinctive ways when positively reinforced; but what did this tell the researchers about vocal creativity and social learning? Intriguingly, these findings suggested that positive social interactions and reinforcement from others increased learning and vocalization creativity in elephants. These findings have implications for functional adaptations and open more questions as to how learned communicative behaviors work in wild elephant populations.
References.
Stoeger, A. S., Baotic, A., & Heilmann, G. (2021). Vocal Creativity in Elephant Sound Production. Biology, 10(8), 750. doi:10.3390/biology10080750
