one of the sneaky places I have found a rare feather is in
the 'bathroom'. It was a bit hard to spot because it blended in quite well and that was the only time I ever saw a feather appear there. I have found them just all over the place. I even tried using light and springy potion to grab that green feather that appears on the alchemy lab back wall! LOL. After a tech upgrade, I saw it and thought it was a real one that I could pick up.