is most popular. Sensation and perception Hearing Their hearing can be measured at the round window as cochlear microphonics and summating potential (of the cochlea), and compound action potential and single-fibre responses (of the auditory nerve). These indicate a best hearing range near 1000 Hz. Earlier reports that their hearing sensitivity varied with the season have been shown to be an artefact of the seasonally varying sensitivity to anesthetics. Single-unit recordings from the auditory nerve show both spontaneous and nonspontaneous responses. Tuning curves show peak sensitivity between 200 Hz and 4.5 kHz. The absolute sensitivity is quite high, with some thresholds at 6 db sound pressure level, very close to human best sensitivity. Olfaction The sense of smell is crucial for this species avoidance behaviours. Living in bush lands that are so prone to fire means skinks have to easily be able to detect smoke. During studies, it was proven that T. rugosa engaged in more active behaviour such as pacing and tongue flicking in the presence of smoke. Scientists have concluded that fires are detected by their olfactory senses. Visual perception It has been discovered that bobtail lizards maintain the ability to navigate home when displaced from their home range. This remarkable ability is due to visual cues from light polarisation and ferromagnetic detection, forming a sort of "celestial compass" that provides the lizard a sense of direction when coming back home. However, this ability only persists until about 800 metres out of the home range, and further displacement distances means the skink is too far away to navigate. Conservation status Under the IUCN Red List, Tiliqua rugosa is categorised as Least Concern. Its population is stable and for the most part there are no significant threats. However, the subspecies T. r. konowi, located on Rottnest island, is considered Vulnerable. References Further reading Reptiles of Western Australia Pets in Australia Reptiles described in 1825 Taxa named by John Edward Gray Skinks of Australia Tiliqua