Chickens have a social hierarchy — it's literally a pecking order — yet chicken cannibalism is not an uncommon occurrence. Chickens have been known to peck, tear, and even consume the skin, tissue, and organs of others in a flock.
Although cannibalism among chickens (and other types of poultry) is more common in certain breeds, the aggressive behavior can also be limited and controlled via preventative measures. These include giving chickens plenty of space to avoid overcrowding, making sure water and food resources are available, and giving chickens a way to avoid too much sunlight. (Chickens should get a maximum 16 hours of light, artificial or otherwise, per day.)
As cannibalism is a learned behavior for chickens, it can spread through a flock.