Thermal Relations of Some Australian Skinks (Sauria: Scincidae)

Abstract

Preferred body temperature (PBT) was measured in 19 species of Australian skinks of the genera Ctenotus, Egernia, Eremiascincus, Hemiergis, Leiolopisma, Sphenomorphus and Tiliqua. Field-active body temperature (FBT) and critical thermal minimum (CTMin) and maximum (CTMax) were also measured for some species. PBT ranged from 17.6 C in H. decresciensis (diurnal measurement) to 35.6 C in C. regius but was intragenerically conservative. PBT was greater in the evening than during the day in nocturnally-active species (Eremiascincus, Hemiergis). Feeding state did not affect PBT of T. rugosa. FBT was very similar to PBT for most species. CTMin ranged from 3.5 C in T. rugosa to 11.4 C in C. taeniolatus and CTMax ranged from 38.6 C in H. decresciensis to 45.5 C in C. uber. Limits of thermal tolerance were examined in relation to PBT. CTMax is positively correlated with PBT with a slope of 0.426 C CTMas/1.0 C PBT (significantly different from 1.0). CTMin is independent of PBT and averages 5.5 C. These correlations hold if FBT is substituted for PBT. Thermal tolerance range is not constant among these species and critical thermal limits do not parallel PBT or FBT.