Social context affects phee call production by nonreproductive common marmosets (Callithrix jacchus)

Common marmosets produce two variants of their long call (phee call) in different situations. Intergroup calls are produced in territorial situations, and intragroup separation calls are produced by marmosets isolated from group members. Marmoset groups frequently include postpubertal, nonreproductive members; their roles in the spontaneous production of territorial vocalizations is unclear. This study analyzed the production of home cage phee calls by nonreproductive, postpubertal marmosets while they were housed in their natal groups and after pairing with an opposite-sex conspecific. Additionally, the production of the separation phee call variant was assessed in both social conditions. The results indicated that the marmosets rarely produced home cage, or territorial, phee calls while they were natally housed. In contrast, both males and females produced the territorial phee call at a much higher rate as early as 4 days after pairing. Age-matched females remaining in their natal groups throughout the study produced home cage phee calls infrequently. Most marmosets produced separation phee calls at a high rate after separation from either their natal group or a partner, suggesting that the makeup of a social group has little effect on an animal's motivation to reunite with conspecifics. These results suggest that the social environment has an important influence on the production of territorial phee calls.