1Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, 2Department of Anthropology, Stony Brook University
Thursday 11:45-12:00, Galleria South
Individually distinct vocalizations play an important role in animal communication, allowing call recipients to respond differentially based on caller identity. However, which of the many calls in a species’ repertoire should be individually recognizable is less apparent. One proposed explanation is that calls used over long distances (long calls) should be more individually distinct than close calls because visual cues are not available to identify the caller. An alternative explanation, based on function, proposes that close calls should be more recognizable because of their importance in social interactions. To examine this question we determine which of nine wild western gorilla calls, given over varying distances and used in differing contexts, were individually distinct. We recorded 2096 calls from 10 individual gorillas during focal follows conducted over 18 months at the Mondika Research Center, Republic of Congo. Acoustic analysis of calls yielded 20 acoustic parameters and we used discriminant function analysis of these parameters to test the proportion of calls that could be correctly assigned to their caller. Results indicated that all nine calls, including both long and close calls were individually distinct, although to varying degrees. Long calls (i.e. screams and long contact calls) and some common close calls (i.e. grunts, grumbles and hums) were highly individually distinct, whereas two other close calls, both used in a single context (i.e. mating and aggression), were less individually distinct. Therefore, both distance and function may have played a role in the evolution of call individuality in gorillas.
This study was funded by The Leakey Foundation, Primate Conservation Inc., Conservation International Primate Action Fund, Richard Leakey and Wildlife Direct, Stony Brook University.