Moulting Sequences in the Development of Tail Plumage of the Superb Lyrebird, Menura novaehollandiae

Abstract

The tail of the superb lyrebird consists of 12 filamentary feathers flanked by two broad lyrates, distinguished by their pigmented bars, and two fine wire-like medians in the middle. The female's tail consists of 12 plain broadfeathers between two lyrates, which are less pigmented than those of the male, and two plain broad medians, all feathers being shorter than those of the male. The tail of the 1st-year lyrebird resembles that of the female, but the lyrates are shorter and only faintly barred. The transformation of the immature tail into the mature form proceeds through a series of annual moults, extending over 6-8 years, during which the three types of feathers change their respective forms. Each bird follows its own course and each follicle acts independently of the others during maturation, but becomes coordinated as the bird approaches maturity. Dimensions and weights are given for the various types of feathers and for complete tails, which are described and illustrated, along with moulting schedules for several birds. Data are given for the total rate of production of keratin in the entire tails and for individual follicles for birds of different ages. The role of the endocrine system in the maturation process is discussed.