The plumage: unique attribute of birds

Feathers are complex structures and characteristic for modern birds.
Feathers can have a range of functions — repelling water, serving for visual communication or camouflage, they can have thermoregulation properties or provide wings for flight. Feathers have a common basic structure of a hollow shaft with branches and sub-branches, but their final shape depends on their function.

Fully developed feathers are lifeless keratin structures that are subject to wear and tear and are replaced at regular intervals.