Animal behaviour refers to the physical expression of bodily movements that result from an internal drive or motivation. A motivation is caused by a real or perceived need and performance of a behaviour that leads to this need being met will ordinarily reduce the motivation to perform the behaviour, at least temporarily. Behaviour is therefore the intervening step between the identification of a need and the satisfaction of that need. The behaviour performed at any given moment is often the outcome of many different motivations, some of which compete (for example the motivations to feed and to hide from predators). Behavioural expression can become extremely complex and dynamic especially where behaviour controls the interactions between individuals