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Giant otter, credit: Christina Mumm

Giant otters may have a vocal repertoire with 22 distinct vocalization types produced by adults and 11 neonate vocalization types, according to a study published in the open-access journal PLOS ONE by Christina Mumm and Mirjam Knörnschild from University of Ulm, Germany.

Giant otters, found in South America, are very social and frequently vocalizing animals. They live in groups that may vary, but generally include a reproductive pair and their offspring, born in different years. Individuals engage in shared group activities and hold different social roles, which provide a basis for complex and long-term relationships. To investigate the connection between vocalization and social complexity, the authors of this study recorded and analyzed the vocalizations of adult and neonate giant otters from wild and captive groups. They classified the adult vocalizations according to their acoustic structure, and described their main behavioral context. Additionally, they provided the first description of vocalizations uttered in babbling bouts of newborn giant otters, which the otters may use to practice for the full adult vocal repertoire.

Researchers found a vocal repertoire with 22 distinct vocalization types produced by adults and 11 vocalization types within the babbling bouts of the neonates. A comparison within the otter subfamily suggests a link between vocal and social complexity, with the giant otters possibly being the most socially and vocally complex subfamily species.