Where are my dragon scats? Victorian grassland earless dragon scat persistence and detection dog-handler team search efficiency

Abstract

Context Reptile species are declining globally, but low detection success is a challenge for reptile monitoring. The Victorian grassland earless dragon (Tympanocryptis pinguicolla; VGED) is the most imperilled reptile in Australia and faces immediate threats from habitat destruction. Detecting VGED is challenging; however, detection dog teams present a promising method. Aims We aimed to (1) determine whether detection dog-handler teams would be a feasible survey method for VGED scat, and (2) measure VGED scat persistence within the environment. Methods Two experienced detection dogs were trained on VGED scat (originally captive sourced, then wild sourced) and assessed on their sensitivity and precision in odour line ups. One dog was then assessed across 21 single-blind area searches for novel captive VGED scat. Concurrently, a scat persistence study occurred using 44 captive scats in the following two treatments: (1) exposed scats and (2) contained scats. These samples were placed within VGED habitat for 50 days and monitored for persistence. Key results Both dogs achieved 100% sensitivity and precision detecting defrosted and fresh captive-VGED scat. However, both dogs failed to spontaneously generalise to wild-sourced scats, requiring a second or third presentation. During search assessments, the detection dog had a sensitivity of 72.9% for captive scats and confirmed species presence in 81.3% of sites. Average time to first detection was 3 min and 30 s; however, this varied amongn search locations (P = 0.01). In the scat persistence study, 36% of the exposed scats persisted less than 24 h and only two remained to Day 50. Conclusions Detection dogs can be highly specific and sensitive to both fresh and degraded VGED scat. However, considering the high rate at which wild scats are degraded and the search intensity required to detect them with dogs, we suggest that VGED scat detection dogs are also trained to detect live dragons, to maximise data collection and chance of detecting VGED presence. Implications Our research supports future involvement of detection dog teams in reptile surveys, while highlighting important considerations when employing dog teams, including access to training samples and survey design.