Abstract # 13387 Poster # 85:

Scheduled for Thursday, August 22, 2019 06:00 PM-08:00 PM: (Alumni Lounge) Poster Presentation


THE CONTEXT OF NON-VOCAL SOUNDS IN WILD WESTERN GORILLAS (GORILLA GORILLA GORILLA): CHEST BEATING AND HAND CLAPPING

R. Salmi and M. Munoz
University of Georgia, Department of Anthropology, Athens, Georgia 30602, USA
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     Repetitive non-vocal sounds are intentional communicative signals present in humans as well as other animals. Gorillas produce two of the most well-known sounds: chest beating and hand clapping. Both signals have been well described in captive studies but only anecdotally in wild populations. Here we present the first systematic analysis of wild western gorilla chest beating (N=81) and hand clapping (N=87) to assess their behavioral context, their flexibility in use, and the age-sex classes that produce them. Data were collected at the Mondika Research Center, Republic of Congo, from a well-habituated gorilla group during two separate periods (Jun-Aug 2007; May 2009-June 2010). Our results show that both signals are highly context specific, with chest beating used only during display and/or play, and hand clapping used only during vigilance and/or play. Age-sex classes differed in signals’ production and use: immatures used both signals only when playing, the male used only chest beating and never hand clapped, while adult females used both signals more flexibly in two contexts instead of one. This study confirms previous anecdotal accounts of non-vocal sounds in western gorillas, and adds crucial information on their flexibility across age-sex categories. While chest beating has been described in both gorilla species, hand clapping as a way to communicate potential danger is unique to western gorilla, and it may represent a cultural trait so far overlooked.