INITIATION AND OUTCOME OF AGONISTIC CONTESTS IN MALE FORM-I CAMBARUS-ROBUSTUS GIRARD, 1852 CRAYFISH (DECAPODA, CAMBARIDAE)

During agonistic contests between size-matched Cambarus robustus crayf ish males of breeding form, the eventual winners and losers initiated approximately the same number of fights. However, winners and losers d iffered in the frequencies and types of initiation behaviours used. Th e losers used almost exclusively the more subtle Ambivalent Contact in itiation behaviours, whereas the winners used primarily the aggressive Lunge and Claws Raised initiation behaviours. The eventual losers ini tiated the vast majority (81.5%) of the very first fights in the overa ll agonistic contests. The type of initiation behaviours used by these crayfish from the beginning of the agonistic contests allows us to pr edict the eventual status (dominant or subordinate) of each of the two combatants. Furthermore, the frequency of the Lunge initiation behavi ours used by the winners is significantly and negatively correlated wi th the total time spent fighting. As the dominant-subordinate relation ship between the two combatants of each pair becomes established, ther e is a reduction in both the number and the duration of fights.