A Parrot's Tail

When molted feathers are replaced by new ones, the new feather grows out with a protective casing of hard tissue, not unlike a fingernail. This casing (and the growing feather) are itchy and the skin where it's emerging is a little tender. Eventually, however, the casing dries and is preened away, revealing the new feather curling underneath.

For some reason, Laka doesn't like to preen her tail feathers, and leaves the casings on for a lot longer than other feathers.

Just from normal activities, however, the casing gets knocked about and eventually unravels (as you see above) or splits and falls away - but, again, it's rare to see Laka working on loosening the feathers.

She's recently moulted her two longest tail feathers and the photos above show the new ones growing in.