Ownership influences the outcome of male-male contests in the scincid lizard, Niveoscincus microlepidotus

Male snow skinks (Niveoscincus microlepidotus) in the Tasmanian highlands have broadly overlapping home ranges, and fight vigorously (often with substantial damage to one or both participants) upon encountering another adult male. We observed 32 male-male contests, involving at least 49 different males, during a five-year field study near the summit of Mount Wellington. Bouts involving similar-sized lizards typically continued for longer than bouts involving a greater size disparity between the combatants. Resident males won 72% of all bouts, despite a lack of any significant difference between residents and intruders in body sizes, relative head sizes or body condition. Thus, prior residency of a site appears to be the major determinant of success in male-male rivalry.