Effects of pair-bond and social context on male-female interactions in captive titi monkeys (Callicebus moloch, Primates : Cebidae)

In monogamous species, an abiding relationship between a specific adult mal e and a specific adult female is a defining feature of the social system. T he interactions between these individuals are influenced by many factors, i ncluding not only the history of their relationship (for example, developme nt of a mutual bond), but also the immediate effects of the prevailing soci al context (for example, presence and sex of extra-pair conspecifics). In t his study we examined the effects of an existing bond and of social context on interactions between adult heterosexual pairs of the monogamous titi mo nkeys (Callicebus moloch). Twelve adult males and 12 adult females were tes ted with their cagemates and with an unfamiliar partner of the opposite sex in five social contexts: (1) mated male-female pair; (2) unfamiliar pair; (3) single female; (4) single male; and (5) empty stimulus cage. Results sh ow that mated pairs were more affiliative than unfamiliar pairs and differe ntiated social contexts more sharply. Males were more responsive to context than females. Distance between mates was less and physical contact was mor e frequent in the presence of male-female pairs or a single male, than in t he presence of a single female or an empty cage. These findings suggest tha t the presence and sex of strangers have a stronger influence on male-femal e interactions when the pair has an existing relationship.