bird wings are similar anatomically to human arms, so one might use a low-poly human
model in which everything but the arms were invisible, then attach a set of primary feathers
to the back of an elongated human hand, attach a set of secondary feathers to the back of an
human fore-arm, then attach a set of tertiary feathers to the back of an human humeral joint
(called shoulder in poser).
it might work like a real bird wing without having to do the JPs, and the feathers
wouldn't be affected by said JPs.  I heard a rumour that the standard practice was to
provide bird models in two positions (wings folded and wings spread), which is somewhat
limiting when it comes to animation IMVHO.  perhaps they did it like that because they
erroneously included the feathers in the bend zones.