Artificial Waterbodies: A Valuable Source of eDNA for Detecting Threatened Birds

Environmental DNA (eDNA) has transformed biodiversity monitoring, especially in aquatic environments; yet, its application in terrestrial habitats remains limited. In arid regions, artificial waterbodies, such as farm dams and water troughs, serve as essential resources for wildlife and offer a promising but underutilised opportunity for eDNA-based detection. Here, we designed and validated a highly sensitive, species-specific quantitative PCR (qPCR) assay to detect the nationally threatened southern squatter pigeon (Geophaps scripta scripta). We validated the qPCR assay in the field by successfully detecting the target species at extremely low DNA concentrations (1 × 10⁻⁷ ng/μL; r² = 0.992) using both active syringe and passive filtration methods across multiple farm dams and water troughs on a 20,000-ha cattle property in northern Australia. To complement eDNA analysis, we also undertook standardised 20-min, 2-ha bird surveys at these sites. Positive detections were recorded at both trough and dam sites during the austral tropical dry season. Notably, whilst eDNA detections and visual bird counts aligned in terms of the number of occupied sites, their exact locations did not always coincide, highlighting the complementary nature of these two monitoring techniques. This assay represents a significant advancement in the conservation of this threatened ground-nesting species, demonstrating that eDNA sampling at artificial waterpoints is a viable tool for monitoring terrestrial fauna in remote, semi-arid landscapes.