Two different ways to assess dominance relationships in black and gold howler monkeys (Alouatta caraya).

PEKER SM, OKLANDER LI, KOWALEWSKI M

Porto Alegre, BRASIL

Congreso; XI Congreso Brasileiro de Primatologia.; 2005

Sociedade Brasileira de Primatologia

Dominance hierarchies in multi-male groups are expected to play an important role in their reproductive success. Thus, agonistic interactions, intolerance and dominance hierarchies generally characterize the relationships between males in order to achieve fertilizations. Patterns of cooperative behavior in each species depend in part on its social structure. Dominance rank in several primate species had notable effects on the number of grooming sessions in which the individuals participated. The aim of this preliminary study was to compare the dominance relationships obtained by agonistic interactions with those obtained by a cooperative behavior: such as grooming. We followed one multi-male group of black and gold howler monkeys that inhabit the Brasilera Island (Chaco, Argentina 27°20´S, 58°40´W) for 15 days in January 2002. Group size was 10 individuals (3 adult males, 4 adult females, 3 juvenile males). Dominance rank among males was determined by dyadic interaction matrices made with data of dyadic displacement and agonistic interactions between adult males. Grooming bouts were recorded on an all-occurrences basis between all individuals of the group and were analyzed by X2. The interaction matrices reflect linear dominant hierarchies between adult males (ID Q=0.719, J=0.677. M=0.620). The pattern of grooming bouts given and received was different from random during the study (p<0.O5), the dominant male received higher frequencies of grooming from others members of the troop than did the others males (45.7%). These results showed the same dominance ranks either using the data of agonistic interactions or grooming bouts. This preliminary study reveals affiliative behaviors as a useful tool to describe the dominance relationships in a group. As cooperative and affiliative behaviors are more common than agonistic behaviors, they provide a better amount of data to determine dominant relationships in species where agonistic behaviors are rare.