Because members of a population have a common niche, there is a strong potential for conflict. Agonistic behavior is displayed when there is a contest that will determine which competitor gains access to a particular resource—for example, food or a mate. The encounter involves both threatening and submissive behavior, and may also involve tests of strength. More often, the contestants engage in threat displays that make them look large or fierce, usually through exaggerated posturing and vocalizations. Eventually one animal will stop threatening and end with a display of submission or appeasement, in effect calling an end to the fight.

Much agonistic behavior includes ritual activity so that serious harm does not occur to either combatant. In many circumstances, escalated violence over ownership of a mate or commodity is less an adaptive behavior than it is an exchange of signals, whether threatening or submissive. The agonistic signals...