Effect of a scrub fire on a population of Southern Alps geckos in the Mackenzie Basin

Little is known about the impacts of fire on New Zealand’s lizard fauna. Anecdotal evidence suggests that the direct impact of fire and subsequent loss of habitat are drastically negative for arboreal and grassland species. The impact of fire on saxicolous (ground-dwelling) species is less understood and difficult to presume given we understand little about the protective nature of rocky refugia and species’ reliance on fire-susceptible habitat. In September 2023 a large scrub fire burnt through Pukaki Scientific Reserve (Mackenzie Basin, South Island), which is home to a population of Woodworthia “Southern Alps” geckos. Having completed sampling for geckos in the reserve prior to the fire and at a similar nearby reserve that remained unburnt, we investigated the impact of the fire on the gecko population by conducting systematic searching pre- and post-event. We employed a simple Before After Control Impact study design to control for unmeasured variation. We report a decrease in the catch per unit effort of geckos at the fire-affected site and provide evidence of direct mortality from fire. More work is needed to fully quantify the lasting impacts of drastic habitat loss on the gecko population, especially considering projected increases in wildfire frequency.