Call Convergence within Groups of Female Budgerigars ( Melopsittacus undulatus )

The budgerigar ( Melopsittacus undulatus ) is a promising model species for the study of adult vocal learning. To date, several studies have confirmed the existence of vocal plasticity and, more importantly, rapid imitation of contact calls by adult male budgerigars. Vocal learning has not been investigated in female budgerigars, however. Since one likely function of the contact call is to denote group affiliation, we tested the hypothesis that female budgerigars, when placed into groups, would develop a shared contact call. We recorded the contact call repertoires of eight adult female budgerigars that were unfamiliar with one another, then placed them into two groups. Each group was deprived of visual contact with other birds. Recording sessions continued for the subsequent 8 wks, and behavioral observations were also conducted during this time. Within 4–7 wks, females in both groups converged on a common call type. This rate of convergence is slower than that observed in prior experiments limited to male birds, and much slower than vocal imitation by male budgerigars paired with females. Therefore, while our study documents vocal plasticity in adult female budgerigars, it also suggests that female budgerigars learn new vocalizations more slowly than males do.