Androgen Concentrations and Behavior of Frillneck Lizards (Chlamydosaurus kingii)

We observed adult-like display behavior in newly hatched frillneck lizards, Chlamydosaurus kingii, including hand waving and erection of the frill. Hatchlings were placed together in groups of four for a week at a time and a measure of dominance was scored with respect to gaining access to a basking site. In most cases, the hatchlings were ordered non-randomly with respect to the optimum basking site, suggesting a hierarchy among the lizards. Plasma androgen concentrations were measured in hatchlings and lizards of both sexes of age classes ranging from hatchlings to three or more years old. Hatchling dominance was not related to plasma androgen concentrations, sex, or body size, but there was a positive correlation between dominance and mass gained over the six weeks of observations. Plasma androgen concentrations were low in all age and sex groups except adult males three or more years old, although two-year-old males had slightly elevated concentrations. A few (8%) two year old males had scars, presumably from intraspecific fights, but many (46%) males three or more years old had scars. No females or males younger than two years old were scarred.