TARGETS AND TACTICS - THE ANALYSIS OF MOMENT-TO-MOMENT DECISION-MAKING IN ANIMAL COMBAT

Even though injury and death are more common consequences of fighting among animals than once believed, they are still relatively infrequent . Modern evolutionary models of animal combat have emphasized that giv en the threat of retaliation, animals only escalate to more injurious fighting if the benefits outweigh the costs, and then only if threat a nd bluff fail to achieve the goal. Such models stress the role of comm unication as to whether animals decide to escalate or not. An alternat ive view is that failure to produce injury or death arises from the ne utralization of one animal's attack by another's defense. That is, att ack and defense end in a stalemate that may be misinterpreted by outsi de observers as an absence of injury producing behavior. As attack typ ically involves the biting or striking of specific body targets, movem ents and postures occurring during combat need to be analyzed with res pect to their role in gaining or averting such contact. For example, i n the combat of muroid rodents the attacker targets the lower dorsum a nd flanks (low threshold) or face (high threshold), whereas a defender may defensively launch counterstrikes against the attacker's face. Tw o combat tactics (supine defense and lateral attack) typically present in the fighting of muroid rodents are analyzed in detail to illustrat e how targets constrain the movements of combatants. Such a functional analysis of combat assumes that the movements and postures performed are related to their role in the attack and defense of targets. Deviat ions from such a strict functional interpretation reveal some of the o ther factors that may constrain the combatants' behavior. For example, body morphology and the aggressiveness of the opponent are shown to b e important in deciding the type of combat tactic to use and how it is performed. Finally, movements and postures that are neutral or even c ounterproductive for attack and defense may be revealed as communicato ry. This approach provides a means of analyzing behavior during the '' heat of combat'' that is typically not dealt with in traditional evolu tionary models. (C) 1997 Wiley-Liss, Inc.