Activity and Thermal Biology of the Sand-Swimming Skink Neoseps reynoldsi: Diel and Seasonal Patterns

Abstract

Body temperatures selected by skinks were measured using a laboratory thermal gradient; observations were made seven times during the diel cycle. Neoseps reynoldsi individuals exhibited significant diel variation in selected body temperature with highs of 31-32 C and lows of 28-29 C during both spring and winter. The length of time lizards selected relatively high temperatures was longer in spring than winter. In spring, lizards exhibited two periods of activity, in the morning and the evening. Lizards selected the highest temperatures when they were active in the evening and the lowest temperatures when they were active in the morning. In winter, lizards were active during the day. Because lizards did not alter their selected body temperature seasonally, activity during both spring and winter corresponded largely to daylight hours when subsurface temperatures were similar to selected body temperatures. Diel patterns of activity and selected body temperature of N. reynoldsi individuals were similar to those of an unrelated African sand-swimming skink, Sphenops sepsoides. These observations suggest that sand-swimming skinks may be convergent in activity patterns and thermal biology as well as in morphology.