A feather is one of the growths covering a bird’s wings and body; it consists of a quill or central shaft with a flat leaf-like surface growing from it. It is also termed a “plume”, though this term is usually reserved for ostrich tail feathers; some authors would define a “plume” as a bunch of ostrich feathers, so it is best to be specific.
The feather is sometimes misblazoned a “quill” or a “quill pen”. Strictly speaking, the quill is the central shaft of the feather, and the quill pen is a quill with its end carved into a nib. These distinctions are often blurred in Society heraldry, and the terms are close to synonymous in practice. It is still best to use the correct term.
In mundane heraldry, the default feather is an ostrich plume, as in the “shield for peace” of Edward the Black Prince, c.1350 [HB 152]; the Society’s default feather is a more generic shape, such as a goose feather (as in the illustration). It is palewise by default, with the quill point to base.
Antoine de Breton bears: Quarterly gules and purpure, a feather bendwise Or.
Adelicia Marie d’Argent bears: Argent, a sheaf of three peacock feathers proper, tied Or.
Salina of the Dale bears: Gules, two merlin feathers in pile, points crossed in nombril point argent.