What causes this and what can I do? I came home to find my favorite chick pecked to death tonight. We just placed them in their new coop 2 days ago. It is 6 times bigger than what they were in before. I have/had 26 total. They are 4 weeks old. It appears that the black sex links are pecking the new hampshire reds. Their new coop is 80 sq ft and has 2 roosting bars. They did this before when they were about 2 wks old. Is it the breed?