What are the types of feathers found on birds, and what are their purposes?

Contour feathers give the bird its outward form; those contour feathers that extend beyond the body are
used in flight and are called flight feathers. The small, soft feathers located under the contour feathers are
referred to as down feathers; their primary function is to conserve body heat. Short, hair-like feathers, called
filoplume feathers, are found over the bird's entire body. They play a key role in sensory function and serve
as insulation. They are believed to send information about how feathers need to be adjusted to keep them in
place during preening, display, and flight. These filoplume feathers appear as the hairs on chickens that have
been plucked of their contour and down feathers. Powder-down feathers have tips that break down as they
mature and release a talc-like powder that provides waterproofing and luster; these feathers are found on
parrots and cockatoos.