Behavior and behavioral needs.

An understanding of behavior is important in any consideration of poultry welfare. Behavior is a good indicator of states of suffering such as fear, frustration, and pain. It might also be possible to use social interactions as indicators of welfare. The possibility of using "luxury" behavior, such as play and exploratory behavior, as an indicator of positive emotional states, requires investigation. Important welfare consequences arise from the fact that some behavior may be so strongly motivated as to constitute a "need". A behavioral need will arise in the case of behavior, such as nesting, that is controlled largely by internal factors, because these factors will be present no matter what type of environment is provided. Behavior triggered largely by external stimuli, such as responses to predators, will not give rise to a need if the external factors can be removed from the environment. Dustbathing is an example of behavior controlled by complex interactions between internal and external factors; the extent to which this constitutes a need is still being debated. If a behavioral need arises, then it is important that the environment provided allows it to be performed without damage to the performer or other birds. It should also be remembered that birds may need to perform behavior, including appetitive as well as consummatory elements, although the functional consequences of these are no longer required for survival. Finally, the performance of certain behavior leads to an increase in health or physical condition that improves welfare later in life.