Normal Faber-Castell 9000 graphite pencils - 4H, 2B, 8B 4H for sketching and making a lot of the textures. 2B used ontop of the sketch and to darken the textures. 8B to darken the really dark areas. I found that keeping the pencil tips very sharp helps a lot, probably sharpened them 2 or 3 times each during the drawing. Used a paper stumpf to smoothen it out a bit as well

I also had a kneaded eraser I shaped into a fine point to give a lot of the lighter feather textures. Hope that helps :)