FIGHTING DYNAMICS OF MALE COPPERHEADS, AGKISTRODON CONTORTRIX (SERPENTES, VIPERIDAE) - STRESS-INDUCED INHIBITION OF SEXUAL-BEHAVIOR IN LOSERS

Adult male copperheads (Agkistrodon contortrix) fight for priority of access to females during the mating periods in spring and late summer. During fights, one male abruptly quits and retreats, and the other ch ases in pursuit. One male thus emerges as the winner and the other as the loser. Reversal of this outcome does not occur during the time of observation (30 min) nor in 24 hr postfight trials. In all cases, winn ers gain priority of access to females. Losers, in contrast, do not pu rsue females nor gain access to them, even when winners are removed fr om the arena. In this study, courtship performance of male A. contortr ix was studied in the laboratory using subjects with either winning or losing experience from staged fights. All males used first were teste d with a single female to determine courtship performance prior to the agonistic trials. From these tests, each male was given a single cour tship score of 0 (no courtship) to 3 (most intense courtship). Only ma les receiving a score of 2-3 were used in the initial agonistic trials . All staged fights were conducted in a large arena and involved two m ales and one female. Following fights, winners and losers were tested again for courtship performance. In trials conducted at 24 hr and 7 da ys postfight, only losers were tested. It was found that prefight cour tship scores were not significantly different between winners and lose rs. At 30 min postfight, most losers showed complete suppression of co urtship behavior (score 0). Winners, in contrast, showed equivalent or an increase in their courtship scores. At 24 hr postfight, courtship scores of losers remained significantly lower than their prefight scor es. At 7 days postfight, courtship scores of losers were not significa ntly different from their original prefight scores. Fighting behavior in free-ranging A. contortrix represents a potentially significant cos t to losers if it is associated with loss of reproductive opportunitie s. Recent evidence from hormonal studies indicates that inhibition of courtship and fighting behavior in male A. contortrix is stress-induce d. (C) 1996 Wiley-Liss, Inc.