Otago Schist lizard habitat

Rock outcrops provide distinct physical resources for biological species that depend on them for persistence in terrestrial environments. This paper synthesises existing and new information to characterise and quantify geological features of tor outcrops in Otago Schist that host indigenous rock-dwelling lizards. The highest grade of metamorphism and structural reconstitution of schist, Textural Zone (TZ) 4, dominates regional lizard distribution, with some spillover into less well-foliated TZ 3 schist. Quartz lineations, abundant cross-cutting quartz veins, and joints are favourable for making ridges of protruding tors in TZ 4 landscape. The principal lizard habitat is in narrow (<6 cm), recessed (up to 30 cm), wedge-shaped pelitic schist cavities eroded beneath relatively erosion-resistant psammitic schist layers. Both schist lithologies provide basking surfaces for lizards but surface temperatures were highest on pelitic schist during experimental sun heating. The lithological controls on tor outcrop morphology provide explanatory and predictive data for habitat carrying capacity of lizards across Otago, although differences may exist between Caples and Torlesse Terrane schists in refuge density. This information can be integrated into conservation initiatives to preserve and enhance lizard populations.