To some extent we have to move from Realism to Impressionism.
You could chose to carve in real feathers. In my swan, however, I've chosen to be more like a painter and imply them, mainly because when I look at swans I see a sort of scuptural form in the bod: the feathers all merge together and individually carved feathers are hard to see.
So, think of yourself as a painter. The surface of the swan is your canvas.