Aggressive behaviour and social dominance in the six-lined racerunner (Cnemidophorus sexlineatus)

Abstract

Field and experimental studies on the lizard Cnemidorphorus sexlineatus (six-lined racerunner) were made on marked populations in Oklahoma. Aggressive chases, followed often by biting, were common in both field and confined populations. As a means of testing dominance, as indicated by aggressive activity, seven groups of racerunners were confined in simulated natural habitats both indoors and outdoors. In any particular encounter between two individual lizards, the pursuer was recorded as dominant and the pursued as subordinate in social rank. Each group had one or two individuals which were more aggressive and accounted for over one half of the recorded encounters. Males were usually dominant over females, and the smallest lizards were the most subordinate. Dominant lizards were more active over longer periods of time. A peculiar submissive posture was observed occasionally in subordinates. The retreat behaviour of the female was sometimes different from that of the male. In the field, aggressive behaviour could not be directly related to possible territoriality. Courtship display was not apparent for this species and the chase and retreat behaviour may be a necessary part of sex recognition and attraction.