Context and sex differences exist in the acoustic structure of phee calls by newly-paired common marmosets (Callithrix jacchus)

Captive common marmosets of all ages robustly produce a "separation" phee c all during brief separations from their group. In contrast, a second struct ural variant, which may function as an intergroup call, is produced in the home cage primarily by the reproductive adults. A previous study found that postpubertal but nonreproductive offspring rarely produce phee calls when in the home cage with the natal group, yet these marmosets call frequently after pairing with an opposite-sex partner. The sudden increase in home cag e phee calls may indicate the rapid onset of intergroup calling. Alternativ ely, marmosets may be producing the separation phee variant as a result of separation from the natal group. The present study investigated whether phe e calls produced by recently paired individuals in the home cage were struc turally distinguishable from their calls recorded in a separation paradigm. We also tested whether sex differences, known to exist in the calls of mat ure adults, could be found in calls recorded from younger, nonreproductive animals separated from their natal groups. We analyzed 18 acoustic paramete rs of phee calls produced in the home cage after pairing and of calls produ ced during separation both from the natal group and from a new mate. Discri minant function analyses found that home cage calls were clearly discrimina ble from separation calls (average 91.7% correctly classified), indicating that the rapid increase in home cage phee call production shortly after pai ring is not a consequence of separation from the family group. Postpubertal marmosets appear to show a rapid behavioral adjustment to separation from their natal groups. Additionally, sex was clearly discriminable in calls re corded both before and after pairing (average 86.8% correctly classified). Like calls recorded from well-established paired marmosets, phee calls prod uced by recently paired, postpubertal marmosets are discriminable by contex t and sex. (C) 1999 Wiley-Liss, Inc.(dagger).