Table 3.

Behavioral ethogram ¹.

Behavior	Description
Feather Pecking	One bird pecking at feathers of another bird can be (a) gentle peck (nibbling or gentle pecking in which feathers are not removed or pulled) or (b) severe peck (vigorous pecking to feathers in which feathers are often pulled, broken, or removed).
Threat	One bird standing with its neck erect and hackle feathers raised in front of another bird.
Aggressive pecking	Forceful downward pecks directed at the head or neck of other birds
Threat Kick	One bird forcefully extending one or both legs such that the foot strikes another bird.

¹ Modified from Hu et al. [178].