Hey Joe,
Very close to me is an area where 100's of Great Blues hang out. I've picked up their feathers as well and have experience exactly the same thing as you. To me they're unusable. I guess if the feathers are to the point of falling out they're past the point of usefulness for us and the heron. I've never seen a fresh carcass of one up close to see if the feathers are of a higher quality but am now curious. I believe I've seen old patterns that called for heron feathers so they must have gotten good feathers. Sorry to not be of more help.
Tom
