The barbs of powder feathers ​ — the only feathers that grow continuously and are never molted — ​ break down into a fine powder that is thought to help waterproof the bird’s plumage.
Puuderudusuled on ainsad suled, mis kasvavad lakkamatult ega vahetu kunagi. Nende udemed pudenevad peeneks pulbriks, mis aitavat kaasa sulestiku märgumatusele.