Bald eagles have 7,000 feathers. Feathers consist of interlocking microscopic structures that are light, but very strong. Layers of feathers trap air to insulate birds against cold and protect them from rain.
Use of feathers permit.
Feathers are made of keratin and grow continuously, the same as an eagle's talons and beak. Feathers grow from follicles; if a feather follicle is damaged, the feather could possibly grow back incorrectly or it might not grow back at all.
Feathers grow quickly; during molting, the new feather pushes out and replaces the old one. Eagles molt in patches, taking almost half a year to replace feathers, starting with the head and working downward. Not all feathers are replaced in a given molt.