I recently began raising 4 chickens and all seemed well last night when I put them to bed and today I found one dead in the coop. There are no obvious signs as to what happened but they all looked healthy and were eating and drinking well. I have a suspicion that one of the larger birds may have done the other in??? She is now following the other two around (who are quite a bit smaller) and occasionally pecking at them. What should I do next?