Thermal ecology and structural habitat use of two sympatric lizards (Carlia vivax and Lygisaurus foliorum) in subtropical Australia

Abstract

The thermal ecology and structural habitat use of two closely related sympatric lizards, Carlia vivax (de Vis) and Lygisaurus foliorum de Vis, were examined in an open sclerophyll forest in subtropical Australia. Comparable mean body temperatures (Tb) and habitat temperatures (Thab) at the point of capture were recorded for both species. However, sex-related differences in the thermal variables for C. vivax, with females displaying higher temperatures than males, resulted in some significant differences in Tb and Thab between the species. Variation in T b, and Thab within and between species was unrelated to time of capture. The difference in Thab within C. vivax suggested that females were selecting warmer thermal environments than males. Both C. vivax and L.foliorum used most structural features of their habitat randomly as indicated by a similarity in canopy, shrub, ground, log and litter cover and litter depth between habitat surveys and random surveys. However, C. vivax displayed a preference for ground vegetation (height <1 m) and litter cover with significantly higher cover recorded where these lizards were captured compared with random surveys. There was no effect of sex on structural habitat used by either species. Thus, the warmer thermal environments selected by female C. vivax may differ from those selected by males in sun/shade patterns or additional habitat features not measured in the present study. Significant associations between specific habitat features and Tb matched broad habitat descriptions for C. vivax and L.foliorum. This suggests that thermal considerations have direct interactions with the structural habitat preferences of these species. The significant association between Tb and ground cover for C. vivax corresponded with the non-random use of ground cover by this species, whereas L.foliorum utilized all structural features randomly, despite an association between Tb and litter cover. The relative abundance or scarcity of individual structural habitat features may influence whether an association between those features and Tb is reflected in non-random patterns of habitat use.