Possibly.Ok.....I'm also thinking boredom.
I recently measured the chicken run and did the math with my current flock and it turns out that each bird has 16.5 sq footage of space. What could be wrong?
Cannibalism doesn't care about space.... What started it is the question. I'd question the feed first. Go up to the highest protein level grain as possible. I'd have them on layer pellets by now, though some wouldn't agree.