i have 7 bantams in various breeds, three are most likely cochins and they are all missing feathers on their shoulder blades (where the bony part of their wing bends). they are 5 weeks old and in a fairly large brooder box with 7- 5 week old standard chicks. they do have an outdoor space during the day...it is actually our garden box that we will be planting soon. anyway, i never see any fighting or problems among the flock. some roost while they sleep but many like to cuddle up together. these three are always in a sleeping heap of chicks...is it possible that the feathers are just being worn off? why would it just be these three? is this common? i haven't made any changes to their habitat yet but i don't want to be negligent if this is a problem.