BODY-SIZE AND AGONISTIC EXPERIENCE AFFECT DOMINANCE AND MATING SUCCESS IN MALE COPPERHEADS

Fighting behaviour in adult male copperheads, Agkistrodon contortrix ( Serpentes, Viperidae), was investigated in the laboratory to assess th e relative importance of body size and type of agonistic experience as determinants of dominance and mating success. Seven experiments were conducted. In each experiment, trials were run using two adult males a nd one female in a large arena. The first experiment tested the influe nce of body size. All males tested had no recent fighting experience f or 6-12 months, and one male of each pair was 8-10% longer in snout-ve nt length and had greater mass. In all cases, larger males won fights and were first to locate, court and guard females; thus, larger snout- vent length was an important determinant of fighting success and prior ity of access to potential mates. Males with either winning or losing experience from the first experiment were used in six subsequent exper iments on the relative importance of snout-vent length and agonistic e xperience in attaining dominance and mating success. Losing experience had a greater effect than snout-vent length on subsequent fighting su ccess and gaining priority of access to females. Winning experience, i n contrast, did not increase the probability of winning subsequent fig hts; however, winners appeared more excitable and none deferred from c hallenges of other males. The asymmetry in effects of single experienc es of victory and defeat is consistent with studies on other vertebrat es and supports the hypothesis that losing lights in males negatively affects behaviour directly related to their fitness. (C) 1997 The Asso ciation for the Study of Animal Behaviour.