Feather plucker or mites/lice?

[BeetleChick]

I have 2 - 6 week welsummers and 5 - 5 week ameraucanas/eastr eggers. They are in a little tikes playhouse. One of the welsummers walks up to another chick and plucks her, now 5 out of 6 are missing feathers down tge center of their back and around their tails. They are very skittish, here's a picture.

The plucker

 

[gander007]

Sounds like they need more room ...

I have had several over the years who just enjoy plucking others
and it is a pain because it makes it hard to sell a chicken with
out feathers or feathers missing and other chicks who only pluck
when roosting and it can be a nasty habit for some and the only
sure way I have found is to separate them in different cages and
this can be a time consuming task ... I have even tried putting on
bad tasting medicine but the chicks just peck elsewhere ....