Abstract # 110:

Scheduled for Friday, August 18, 2006 10:15 AM-10:30 AM: Session 10 (Regency East #2) Oral Presentation

Social contexts of reunion displays in wild capuchins, Cebus nigritus.

J. W. Lynch Alfaro
Washington State University, College Hall 208, Department of Anthropology, Center for Reproductive Biology, Pullman , WA 99164, USA
     Reintroduction of capuchins (Cebus apella) into their social group in captivity can evoke “reunion display” behavior, including hugs and “sirena” screams. One hypothesis is that reunion displays reaffirm social relationships, particularly in the context of social tension. Captive data suggest reunion displays are male-biased, and females never perform “sirena” screams. Here reunion displays in wild Brazilian black horned capuchins (Cebus nigritus) are analyzed for ecological and social contexts, behavioral components, and individuals involved. Out of 5325 activity scans, only four scans were recorded as “reunion hug”; on average, capuchins spent about 0.075% of their time hugging. The 66 reunion displays observed ad libitum with both members identified by sex included 42 male-male dyads, 17 male-female dyads, and seven female-female dyads. Dyads in reunion displays were significantly more likely to be male-male pairs compared to the expected random distribution based on group membership (Chi-squared= 121.07, df = 2, p < 0.001). In fact, at least one male participated in every display that included a “sirena”. Female-female pairs hugged but never screamed, and only the alpha male engaged in Sirena-Hug displays with females. Displays occurred: when individuals re-united after traveling out of contact; after intergroup encounters; or across different groups. Reunion displays were “socially contagious”, with multiple dyads performing displays in rapid succession after re-establishing contact. Male reunion displays may be honest advertisements of united alliances.