Facultative Climbing in Two Widespread Skink Species Found Along the East Coast of Australia

Many primarily ground-dwelling vertebrates are known to occasionally climb trees and other vertical structures. This includes, although is relatively rarely reported among, terrestrial reptiles. The functions of facultative climbing or scansoriality are generally poorly known, although the reasons for doing so may include foraging, thermoregulation, access to favourable nesting sites and predator avoidance. The garden skink (Lampropholis guichenoti) and weasel skink (Saproscincus mustelinus) are native to Australia, widely recognised as terrestrial species that shelter and forage among leaf litter and ground debris, with the former species previously regarded as rarely or not ascending more than 30 cm from the ground. However, in spring 2017, summer 2018 and summer 2025, three L. guichenoti were recorded climbing to heights of 164 cm, 287 cm and 125 cm, respectively. These observations demonstrate that although it may be uncommon, L. guichenoti is at least capable of climbing to substantially greater heights than had previously been reported. Although basking behaviour was observed in all instances, the possible reasons for facultative climbing by this species otherwise remain largely unknown. Two observations were also made of S. mustelinus having climbed to heights of 92 cm and 203 cm in 2022 and 2023 respectively. This species is known to regulate its body temperature primarily through thigmothermy among terrestrial microhabitats such as decomposing litter and woody debris, and in both instances of this species climbing, similar microhabitats were available at the heights the individuals were observed. The observations presented here highlight the value of publishing observational notes on previously unreported behaviours expressed by species that may otherwise be commonly encountered or well understood.