afterfeather-- grouse and pheasant; increases insulation.
contour feather (these include flight feathers)--can be amazingly modified.
down feather--increases insulation. Two kinds exist: natal = short calamus with long flexible barbs that don't interlock, gives protection; adult = has rachis, serves as insulation.
semiplume--intermediate between down and contour feather with no interlocking barbs, provides insulation.
filoplume--"hairs" on domestic fowl after plucking, has long rachis with small trace of vane at top. It is found on napes and backs of some passerines. The function is unclear. Sensory?
rictal bristles--along the edges of birds' beaks. May help in flycatching.
powder down--strangest of all feathers, these continually grow, breaking off to form talcum-like powder. The exact function is unknown. They occur singly or in patches and can be a taxonomic tool on herons (where may remove fish oil): bitterns = 2; typical herons = 3; Boat-billed Heron and some Tiger Herons = 4. Powder down also rarely occurs in passerines.
Bare-throated Tiger Heron