Sexual dimorphism in the shape of the primary wing and tail feathers of the sky blue parakeet (budgerigar), Melopsittacus undulatus (Shaw, 1805) (Psittaciformes: Psittacidae)

Difference between sexes was quantified in this study using outline based-geometric morphometric analysis on the shape of the primary wing and tail feathers of the sky blue strain of parakeet bird Melopsittacus undulatus (Shaw, 1805). Results of Discriminant Function Analysis (DFA) and Principal Component Analysis (PCA) utilizing the coefficients derived from Elliptic Fourier Analysis (EFA) consistently showed that sexual dimorphism is present in the said species with differences primarily explained by the variations in the tip and outline of the flight feathers. Females generally have slightly rounded tip and partially curved (inward) feather outline while males have feathers with slightly pointed tip and more or less straight feather outline. However, no difference between sexes was observed in the shape of tail feathers. It is suggested that based from this study, a more complete understanding and proper identification on the biological basis of the observed wing shape differences are needed which could be elemental in the proper and effective conservation of this species.