Re: Wild Duck Feathers..
I have many friends that bring me their bird carcass so I can pull feathers. I bag them in like kinds and place them in the freezer until I decide to dye a batch, sometimes they stay in there a couple years before use.
Freezing for a month or so from my understanding is long enough.
*Comments posted above are only my opinion. I may be right....ehhh.....I'm certain they're wrong. Take 'em for what they're worth.*