Giant otters hum, scream, say ‘hah’ and more

Underappreciated vocalists make 22 different calls as adults


OTTER SPEAK  Giant otters make a rich variety of sounds as they negotiate their social lives, says a new study analyzing their vocal repertoire.

Joachim S. Müller/Flickr (CC BY-NC-SA 2.0)

Guest post by Susan Milius

Giant otters deserve more scientific attention for their vocal repertoire. The South American mammals make 22 distinctive adult calls such as whistles, three kinds of screams and various hums, a new study finds.

Researchers recorded wild and captive animals. Adult giant otters often bark when greeting group members, and they give a short hum when emerging from water. A “hah” sound can be a warning or a sign of submission.

Weighing up to 34 kilograms, a bit more than a typical 10-year-old boy, giant otters (Pteronura brasiliensis) typically live in groups of three to nine. The other 12 otter species include solitary creatures as well as social ones. So otters offer an overlooked opportunity to test ideas about how social life affects complexity in vocal communication, say Christina Mumm  and Mirjam Knörnschild of the University of Ulm in Germany November 12 in PLOS ONE.

OTTER CHATTER  Video clips illustrate the some of the kinds of calls researchers have documented in otter groups.

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