Structural Changes in the Main Rectrices of the Superb Lyrebird Menura novaehollandiae in the Development of the Filamentary Feathers

SummaryThe development of the tail plumage of the female and male Superb Lyrebird Menura novaehollandiae proceeds through a number of moults during which the feathers formed undergo structural changes. The number of barbs in successive 50 mm lengths of the main rectrices (plain and filamentary feathers) (designated ‘barb density’) were counted, starting at the distal end. As the bird grows older, the relevant barb densities decrease. The paper identifies the changes in structure of a feather during the growing process. The case histories of several identifiable subjects are given, illustrating the independent behaviour of the individual follicles within the tail plumage of particular birds and between different birds.