Comparison of camera trapping, visual stakeouts and eDNA surveys for detection of platypuses (Ornithorhynchus anatinus) in north-eastern New South Wales

The platypus (Ornithorhynchus anatinus) is a unique monotreme mammal from eastern Australia which can be difficult to study due to its semiaquatic lifestyle and nocturnal nature. Understanding which methods are most effective for studying this elusive species is key to optimising conservation actions. We compared the effectiveness of detecting platypuses using eDNA surveys with qPCR and metabarcoding analysis, camera trapping and visual stakeouts in waterways across the New England Tablelands and quantified activity patterns to optimise survey design. Out of ten survey sites, eDNA surveys with qPCR analysis, camera trapping and visual stakeouts were all effective, detecting platypuses at eight, seven and six sites, respectively. The least effective method was eDNA surveys using metabarcoding, which detected platypuses at only three sites. Camera traps showed platypuses were most active immediately after sunrise and just before sunset. For occupancy surveys, eDNA sampling using qPCR analysis is the most effective method; however, camera trapping and visual stakeouts were also useful, particularly in providing additional data on platypus behaviour.