UC Davis

Communication reinforces vital social bonds across the animal kingdom. Some of the most rare and specialized social systems require similarly specialized communication. One of the rarest social organizations in the animal kingdom, especially amongst mammals, is monogamy. Monogamous mates rely on a variety of communication modalities to find and initiate a bond, maintain their bond, coordinate daily activity, raise offspring, avoid predation, and defend shared resources, among other behaviors . Understanding these communication signals, both their structure and function, is of utmost importance in order to fully understand closely bonded social species. Coppery titi monkeys (Plecturocebus cupreus) are monogamous, South American monkeys who form selective, enduring psychosocial emotion attachments, referred to as pair bonds. Titi monkeys must form and maintain long term relationships, coordinate biparental care, and maintain control over a shared territory. These pair-bonded monkeys provide the perfect model system in which to investigate a variety of communication modalities in relationship to the unique pair bond. At the California National Primate Research Center, I investigated three aspects of titi monkey communication. First, I assessed patterns of individual identity in the morning adult duet contributions and infant trill vocalizations of this species. Strong patterns of individuality exist in adult duets, such that individuals are identifiable based on vocalizations alone. Second, I assessed female titi monkey responses to a variety of vocal stimuli in a playback experiment. Female titi monkey responses depended more on their own pairing status and reproductive status than the content of the social vocalization, suggesting titi monkeys respond generally to any unfamiliar acoustic signal. Finally, I presented titi monkeys with paired faces of their mate and a stranger in order to test for a partner preference in looking behavior. I found little evidence of visual partner preference based on two dimensional, static photos of titi monkey faces. However, age and pair-bond tenure predicted individuals’ looking behavior in the eye tracking paradigm. In total, this body of work deepens our understanding of two key communication modalities¬––vocal and visual-––in the uniquely pair-bonded titi monkey.