HEAD LIFTING BY FEMALE COPPERHEADS, AGKISTRODON CONTORTRIX, DURING COURTSHIP - POTENTIAL MATE CHOICE

Male copperheads fight for priority of access to females in the mating seasons. Fighting behaviour or combat is characterized by a prominent vertical posture (the challenge display) and a high degree of physica l contact. During courtship, females frequently show a vertical postur e similar to the initial stages of the challenge display of males (hea d lifting). To test whether head lifting influences the behaviour of c ourting males, three experiments were conducted. The first experiment recorded the frequency of head lifting in females during courtship and responses of males with no recent social experience to head lifting. Head lifting was frequently shown by females during courtship, and mal es typically responded to it by giving challenge displays. The second experiment tested responses of males that recently lost fights to head lifting. In trials where courtship occurred, head lifting repelled ma les in the same manner observed during subordination. The third experi ment tested responses of males that recently won fights to head liftin g. In these trials, males frequently challenged females that head-lift ed. In all cases where males challenged females that head-lifted, figh ting never occurred and all males resumed courtship. Previous work and results of this study show that head lifting is not a signal of non-r eceptivity, because females show receptivity (e.g, cloacal gaping) and will mate. The present results show that males of differing dominance status responded differently to head lifting. We suggest that head li fting is a mechanism of female choice involving intraspecific sexual m imicry. (C) 1996 The Association for the Study of Animal Behaviour