And of these thousands of feathers, there is a wide variation of shapes and sizes, depending on the functions they fulfill. Feathers which cover and help mould the shape of the bird are called tetrices . Those which are softest and closest to the skin are plumule feathers and those on the tail and wings which provide flight abilities are called quill or flight feathers. There is one further type, known as filoplume , which are hair-like and lie close to the skin. It is not known what function these provide.
Most feathers consist of the following parts.
The quill is the hard stem which actually joins the feather to the bird's skin. Extending out from the shaft close to the base is the fluff . Further along the shaft comes the web which is the main surface of the feather. The edge of the web is called the vane . The web consists of branch-like barbs which in turn are lined with barbules and troughs .