We studied the activity patterns of two species of viviparous lizards co-occurring in a harsh sub-alpine environment. Activity patterns were studied over the active period, October to March, to investigate differences between an alpine specialist species, Niveoscincus microlepidotus, and a lowland generalist species, N. metallicus, at its altitudinal limit. Distinct differences were found in emergence and retreat times, behavior during the day, activity between the seasons, and total activity over the summer period. Loglinear modeling clearly showed a relationship between sex, season and the behavior of the lizards. Niveoscincus microlepidotus exhibited more variable behavior than N. metallicus, with a capacity to shift from bimodal to unimodal diel activity. Diel and seasonal activity in N. microlepidotus was greatly extended, largely through the use of thigmothermy to supplement shuttling heliothermy.