Behaviour is at the forefront of the organisms - environment relationship and thus should play a central role in an organisms’ ability to respond to environmental change over short time scales and is likely to underpin species climate change responses. Despite this, relatively few studies take the potential for behavioural plasticity into account when studying the effects of current climate change. We tested the capacity for a high and low altitude population of two widespread and two highland-restricted species of a cool climate lizard genus, Niveoscincus, to respond to variation in basking opportunity through changes in basking time and selected body temperature under controlled laboratory conditions. Both widespread and highland Niveoscincus species responded to variation in the thermal environment through changes in the time spent basking. Behavioural responses translated into different effects on body temperature at the species level. Both widespread species reduced body temperatures when exposed to high basking opportunity whereas highland species maintained consistently high body temperatures despite exposure to divergent thermal conditions. Plastic behavioural and body temperature responses to the thermal environment will at least partially mitigate the impact of changing temperatures on these species. Our study exemplifies the importance of incorporating the potential for population and species-level differences in behaviour when examining responses to climate change.