Natal Downs and plumage changes in the Noisy Scrub-bird, Atrichornis clamosus (Passeriformes: Atrichornithidae)

Abstract

The newly hatched Noisy Scrub-bird chick has 60 to 81 natal downs distributed in three paired and two single dorsal pterylae. The downs are most numerous and longest on the capital and spinal tracts. The age of the chicks when the contour feather sheaths emerge and burst on the various regions of the body is described. Males and females show no differences in the natal downs or juvenal plumage. The first moult begins when the chick is 41 to 46 days old. The first basic plumage is like the adult female plumage except that the male has a faint grey pectoral band on the upper chest. The second moult takes place during the bird's second summer, through which it attains the second basic (definitive) plumage. The males differ mainly in having a black upper pectoral band. All plumages are described. The distribution of the 840 natal downs in five paired and four single pterylae (both dorsal and ventral) in one specimen of the Superb Lyrebird is described. The differences in the natal downs and subsequent plumages between the scrub-birds and lyrebirds are discussed.