CANNIBALISM - what is going on?

History:

I have a mixed "teenage" flock of 8wk olds that, until this past weekend, were brooded in my horse trailer.  Once they were fully feathered out, I moved them to a grow-out pen.  Flock composition and feed didn't change (medicated chick feed), except for the lone silkie that typically lives in that pen (and it just occured to me, as I write this, that she may be the problem).  Anyway...now, they are picking out the tails (and literally, the innards) of several chicks/day...and, obviously, killing them.  I lost two today alone.  I can't keep losing them like this!  It's only been 5 days since I moved them out there...didn't have this problem at all in the horse trailer.  What is going on?  Should I remove the silkie and see if she's the problem, or if she's at least starting the problem?  Or have I likely raised a group of cannibals?

I should add...I removed some of the more valuable birds from the group when this started, and put them back in the horse trailer...and they are fine.  No cannibalism there.

What gives???

None of them are injured to start with...but I have had it before where they will start to pick at one, and then it starts to bleed, and then they peck it to death.  But, I can't for the life of me figure out why they would be doing this now :(  If it was a matter of overcrowding (they have more room than before), or poor feed (feed hasn't changed), I would understand.  But why, when there is now more to do, and everythign else has stayed the same, are they suddenly killing each other???

They are all the same age.  And, from the time when I check on them in the morning (when I would blu-kote if I needed to, but no one is bleeding), and when I get home at night, they've killed at least one chick.  So...I don't get the chance to stop the pecking.  I just don't know why its starting...unless the silkie is perpetuating it.  I'm going to pull her out tomorrow and see if that helps.