Thermal biology of a viviparous lizard with temperature-dependant sex determination

1.Eulamprus tytmpanum can attain mean selected temperatures achieved in the laboratory under field conditions, but the proportion of time at that temperature is restricted under natural conditions.2.Females actively thermoregulate in the field, although the efficiency of thermoregulation is restricted by environmental constraints.3.Gravid females in more favourable habitats in the period encompassing the middle third of development (the assumed sex determining period) select higher temperatures, with lower variance and have greater thermoregulatory efficiency than during the rest of pregnancy, thus thermoregulating more precisely during this period.