I understand. I was still thinking that using a mesh and water might be a faster way to get a lot of the feathers. That's the only alternative I can think of aside from picking them out of the poop.
If I collect them, I usually get them when I butcher, but you might try taking a mesh screen or something and putting the whole mess on it and spraying it with water until the poop is gone. You want to wash the feathers anyway. After they're washed and dried you want to put them in the freezer...