MALE-MALE INTERACTIONS IN HETEROSEXUAL AND ALL-MALE WILD MOUNTAIN GORILLA GROUPS

Variation in male dispersal and behavior patterns are components of in traspecific differences in social systems. A comparison of male behavi or in different social settings can be useful for determining which be havioral mechanisms contribute to variability in social systems. Two h eterosexual multimale groups and one all-male group of mountain gorill as (Gorilla gorilla beringer) were observed for over 1100 h at the Kar isoke Research Centre, Rwanda. Data on proximity patterns, dominance r elationships, aggression, agonistic interventions, affiliation, and ho mosexual behavior were compared among the males in these soups to exam ine the influence of female presence, sex ratio, group size, and kinsh ip on male-male interactions. Males in the all-male group stayed close r together, affiliated more, exhibited more homosexual behavior, and w ere more aggressive toward each other than males in heterosexual group s. However, the males in heterosexual groups showed more wounding and more consistent dominance relationships. Kinship did nor influence mal e-male relationships in the all-male group. The males in the heterosex ual soups rarely interacted with one another; they may actively avoid dose proximity to reduce aggression. Results suggest that the variable social system of mountain gorillas may be more strongly influenced by demographic factors, male-female social relationships, and male-male competition for males than by any benefits of male-male relationships.