ASYNCHRONOUS SEASONAL ACTIVITY OF MALE AND FEMALE SLEEPY LIZARDS, TILIQUA-RUGOSA

An eight-year survey of a population of the sleepy lizard, Tiliqua rugosa, near Mt. Mary in South Australia, resulted in 10,771 random encounters of active adult lizards. Among this sample there was a significant change from a male bias in spring samples to a female bias in summer samples. This change coincided with the end of the period when males were paired with females. It appeared that the change resulted from a relatively larger decline in male than in female activity after mating. A similar trend was found in direct observations of the time active and distance moved per day of lizards in pairs at Mt. Mary, and of male and female lizards at another site near Tickera (also in South Australia). Males were more active than females in the spring before mating occurred. Females became more active than males in the summer, after mating. This asymmetry in seasonal activity patterns may be a component of the asymmetrical distribution of reproductive costs.