When new feathers first grow out they are protected by a keratin sheath which eventually is chewed off by the parrot. Keratin is the same material making up our hair and finger and toe nails.
New feathers are also called pin feathers or blood feathers. The pin feather has a blood supply flowing through it. If the pin feather is damaged, a bird can bleed heavily. As the pin feather grows longer, the blood supply is concentrated in only the base of the shaft, and the tip of the shaft encases the feather itself. As moulting birds preen, they remove the sheath, and the feather unfurls.