Spatial prioritisation of survey and management efforts for a threatened pygopodid in south-western New South Wales

Determining species' distributions is challenging for cryptic species that are difficult to detect using standard techniques. The mallee worm-lizard (Aprasia inaurita Kluge, 1974) is a cryptic reptile in the family Pygopodidae, listed as Endangered in New South Wales. We modelled the species' potential distribution (Maxent) to improve understanding of the species' distribution and surveyed potential habitat in the Scotia Mallee region (an area with suitable habitat) from 2018 to 2022, with pitfall traps and artificial refuges (terracotta roof tiles). We completed 11 587 pitfall trap-nights and 3200 tile checks over eight monitoring sessions. Over this period, we detected six vertebrate species (all lizards) using roof tiles and 40 species with pitfall traps, but no mallee worm-lizards. Evaluation of existing records of the mallee worm-lizard from NSW suggested that the state constitutes the north-eastern edge of its continental range, with the species apparently present in low numbers across a wide swathe of south-western NSW. Most records were located within or near to spinifex or porcupine grass (Triodia spp.) communities, on private land. Species distribution modelling provided outputs that are useful for spatial prioritisation of conservation efforts for the species, with region-wide maps showing that much of the Scotia Mallee study area contains potentially suitable habitat for the mallee worm-lizard. However, habitat suitability scores for individual cells in this area were low, in some instances, because of high maximum summer temperatures and soil available water capacity. We anticipate that increasing temperatures associated with climate change may further reduce the suitability of habitat in this area in the future. Cryptic reptiles can be difficult to detect using traditional trapping methods and their distributions not well understood as a result. We deployed terracotta roof tiles as artificial shelters to see if they would be used by the threatened and secretive mallee worm-lizard (Aprasia inaurita) and developed a map of potential habitat for the species across south-western NSW, which can be used to guide future survey and conservation efforts. Photograph by Helen P. Waudby.