Abstract # 212:

Scheduled for Friday, June 21, 2013 11:30 AM-11:45 AM: Session 26 (San Geronimo Ballroom B) Oral Presentation


PEACEFUL SILENT-BARED-TEETH DISPLAYS AS SUBORDINATION SIGNALS IN RHESUS MACAQUES (MACACA MULATTA)

B. A. Beisner and B. McCowan
University of California Davis, Department of Population Health & Reproduction, Davis, CA 95616, USA
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     The meaning of the silent-bared-teeth display (SBT) in pigtail macaques (Macaca nemestrina) is influenced by the signaling context such that in apparently peaceful contexts the SBT communicates subordination, a pattern of behavior, whereas in conflict contexts it communicates immediate submission (PNAS, 104: 1581-1586). However, the SBT in rhesus macaques has been argued to be a formal signal of subordination regardless of the context. Using multi-level GLMs (controlling for rank and ID), we evaluated dyadic-level grooming and aggression with respect to SBT usage across 16,274 dyads from seven captive rhesus groups at the CNRPC. Our results generally support the context-dependent nature of the signal but also reveal some important differences between pigtail and rhesus use of these signals. Peaceful SBTs in rhesus were often accompanied by withdrawal behavior (referred to here as peaceful SBT-leave), which influenced grooming, but not aggression, at the dyadic level. Severe aggression was less frequent among dyads using peaceful SBTs (regardless of withdrawal behavior) than those using conflict SBTs (peaceful vs. conflict SBT: b = -0.49, p < 0.0001). In contrast, grooming was more frequent among dyads using peaceful SBT-stay signals than those using peaceful SBT-leave signals or conflict SBTs (peaceful–stay vs. conflict: ?b = 0.3, p < 0.05) . These results suggest that only peaceful SBTs, not conflict SBTs, function as formal subordination signals in rhesus macaques.