I have such a struggle trying to translate fluffed/puffed feathers onto wings for drawing! Do you have any suggestions?
I'd say practice first by trying to look at the shapes and shadows of fluffy birds when they puff up and how messy they look.
When birds get all puffed up, each feather raises up across the coverts and around the mantle and collar so that air can be trapped in the soft down beneath, but they still follow the contours of the body.
Then its a mess-around time of finding what fits your style better but I'd say the 2 extremes of it are simple messy lines vs heavy shadows and high detail. Having a ragged edge also gives a more fluffy appearence.
Rough lines that just follow where the edge of the wing is can be good for giving a fluffy appearance, where as heavy shadows beneath the lower edges of the feathers can accentuate how fluffed up and lifted they are.
With both styles, you don't have to draw every feather or even draw the feather line drawn right up to the edge of the layer above or below it, and you can give the impression of fluffiness just from line weights alone. Smaller wings will have comparatively bigger feathers so may have less shadows to draw where as big wings have smaller contour feathers so may require more linework and shading.
