I have some 4 week old baby EE chicks and I noticed one that started picking at the fluffy feathers (not the ones coming in) and now it seems like they are all doing it. It looks neurotic. I don't know if they are bored or if it is an actual deficiency of some sort. I give them chicken starter (non-medicated now but I had started with medicated but I just don't like that brand of the medicated that I had them on) with the appropriate amount of protein. They have access to water. I thought about trying to put vinegar in the water but haven't done that yet. Their poo looks great. One of them gets a little aggressive with the others but not enough to hurt and she is in on the picking at feathers too. Any suggestions? It can't be totally normal because I never noticed this with any of my other baby chicks.