Before gaining their final adult plumage, many birds pass through a subadult phase. In the case of this Paradise Riflebird, the subadult male is a dull brown, lacking the satin black and iridescent blue feathers of an adult male. Nonetheless, he practices his courtship dance with other males in an attempt to have it mastered by the time he molts and gains his adult plumage, which can take up to 5 years.
This video accompanies Chapter 4, Feathers and Plumages, Handbook of Bird Biology, 3rd Edition from the Cornell Lab of Ornithology and Wiley Publishing.
Recorded by Timothy G. Laman, Macaulay Library