I investigated geographic variation in a parrot vocalization to obtain an understanding of cultural population differentiation and exchange between hybridizing taxa. The flight calls of Ringneck Parrots (Barnardius zonarius) were tape recorded in Western Australia within and outside the zone of overlap and hybridization between the Port Lincoln (B. z. zonarius) and Twenty-eight (B. z. semitorquatus) subspecies. Measured variables distinguished the Twenty-eight call from those in the overlap populations. Although birds in typical Twenty-eight plumage were present in the overlap zone, no Twenty-eight flight calls were found, suggesting convergence by immigrants. Populations within the hybrid zone also were acoustically differentiated as dialects associated with roosting areas. Observations on the social behavior of the birds indicated that this call functions in coordination of movements of the mated pair. Roost-specific dialects might aid pairs in finding each other in the event of separation during the day's foraging activity.