I’ve come to understand that Sandhill Crane Feathers are on the no-no list so disregard the previous inquiry.

of course any bird you can legally harvest, you can use its feathers for flies - you may not be able to sell the feathers or flies.

What do they taste like (the birds, not the feathers)?

Karstopo is right . They are really good .

Oh they are tasty a little teriyaki marinade and on the grill medium rare served with some bacon wrapped asparagus paired with an ice cold PBR it just don't get no better. Gonna have to go for them next year been a long while since I have shot one.

Wigeon flank is really good for those flies too it kinda pinkish though not very well marked. In all my years duck hunting I never shot a drake bluewing in full plumage always got them in the early season I bet that makes some good materials.

A bunch of smallish ducks have a blue speculum (wing bar); blue winged teal of course but also one of the most prevalent here in Texas the northern shoveler aka the grinning mallard. Shoveler hens are almost impossible to distinguish between a blue wing unless you look at the bill.
I like the green wing teal drakes as their flank is very similar to wood duck flank and makes awesome split wings on smallish traditional catskill style flies like a ginger quill or quill gordons tied below a #14. I think for what you have been tying the gadwall and pintail flank would be the best especially pintail. Pintail also eat good too as their tiny little bills are designed more for grains much like wigeon. I don't care for the gadwall on the eating side because they will take a fair amount of animal matter and even badger diving ducks for whatever they dredge off the bottom.

I have a mess of duck feathers if you ever run out.

Don't know how they taste, but they sure like the taste of peanuts.