Hybrid zones and cultural traits of the Australian ringneck Platycercus zonarius

Two hybrid zones between subspecies of the Australian ringneck parrot (Psittacidae: Platycercus zonarius) were examined for morphological (plumage patterns) and cultural (learned contact flight calls) traits. Mensural traits and plumage patterns also were quantified in a study in the 1960s. My samples were taken from populations in the allopatric distributions of the parental taxa P. z. zonarius (Port Lincoln parrot), P. z. semitorquatus (twenty-eight parrot), and P. z. barnardi (Mallee ringneck) and within the hybrid zones. The two hybrid zones differed in the distribution of plumage patterns: (a) in the zonarius - semitorquatus zone of intergradation all sample locations comprised birds of both subspecies' plumage patterns as well as numerous birds in hybrid plumage and (b) in the zonarius - barnardi zone of intergradation all birds were in hybrid plumage. The cultural trait also differed in the two hybrid zones: the acoustic features of P. z. zonarius flight call predominated in the birds in the hybrid zone with P. z. semitorquatus, regardless of plumage displayed by the individuals; whereas in the P. z. zonarius - P. z. barnardi zone of hybridization the acoustic features of the P. z. barnardi flight call notes evidently have swamped out those of P. z. zonarius. The results on the cultural trait reject 'coexistence' and 'blending' models of cultural interchange but support a 'cultural dominance' model. Hypotheses are discussed concerning historical and behavioral means by which the patterns arise.