First time chicken mom here. My girls seem to be losing quite a few feathers. They are about 12-13 weeks old. Not very visible on their bodies, other than I notice a few gaps on their wings & tails where feathers once were. The coop, run, and yard look like someone had a pillow fight. They aren't pecking each other and they aren't eating the feathers. I feed them starter/grower feed that's always available (coop AND run), feed them scraps of protein, fruits, and veggies, and have chick grit available. They free range for about 2 hours a day. Is this just a stage? Or am I doing something wrong?