 Flight feathers ( <unk> <unk> ) are the long , stiff , asymmetrically shaped , but symmetrically paired pennaceous feathers on the wings or tail of a bird ; those on the wings are called remiges ( singular remex ) while those on the tail are called rectrices ( singular <unk> ) . The primary function of the flight feathers is to aid in the generation of both thrust and lift , thereby enabling flight . The flight feathers of some birds have evolved to perform additional functions , generally associated with territorial displays , courtship rituals or feeding methods . In some species , these feathers have developed into long showy plumes used in visual courtship displays , while in others they create a sound during display flights . Tiny serrations on the leading edge of their remiges help owls to fly silently ( and therefore hunt more successfully ) , while the extra @-@ stiff rectrices of woodpeckers help them to brace against tree trunks as they hammer . Even flightless birds still retain flight feathers , though sometimes in radically modified forms . 
