The damage one chicken can inflict on another is unbelievable. This past spring, when I placed two pullets in the with the rainbow flock, the rooster immediate exerted his dominance by pecking both birds. I watched as he struck each on the head with his beak. One was immediately rendered unconscious and didn't regain consciousness for several minutes. When she did she was unable to walk or even hold herself upright. My first instinct was to finish the job the rooster had started but instead I place her in another cage. For over a week I had to use props to hold her in an upright position and hold both food and water within her reach. During that time she manage to wear her tail feathers off so that she now resembles a rumpless araucuna. While she has regained full mobility and is an excellent layer I am convinced that she suffer brain damage from the rooster's welcoming greeting and it even affected her vocalization as she now sounds like a goose with a sore throat.