Flying birds molt their feathers when they are old and worn because they inhibit flight performance, and the molt strategy is typically a sequential molt. Molting is thought to be unorganized in the first feathered dinosaurs because they had yet to evolve flight, so determining how molting evolved can lead to better understanding of flight origins.
Click here for original story, Research reveals earliest flight-related molting strategy in 150-million-year ancient bird
Source: Phys.org