Dragon detectives: citizen science confirms photo-ID as an effective tool for monitoring an endangered reptile

Context: Among amphibians and reptiles, traditional methods of capture-mark-recapture (CMR) have relied on artificial marking techniques (in particular, toe clipping), which has raised concerns because it may impact climbing ability, survival, and behaviour. A potential alternative involves the exploitation of natural biometric identifiers that are already present, including scale configuration or colour patterns. These natural markers can be applied in photo-based CMR, which has several advantages over artificial markers, including reduced costs, the reduction of harm or stress, and the potential for public participation in conservation and research. Aim: Our aim was to test the feasibility of applying citizen science in the manual visual identification of the endangered Monaro grassland earless dragon (Tympanocryptis osbornei) using dorsal pattern as a natural marker. Methods: We collected photographs of dorsal patterns of wild T. osbornei individuals using a smartphone device under field conditions. We subsequently recruited participants anonymously from the public using social media to complete an online survey, in which they were asked to correctly match these field-captured images of individuals from small image pools, mimicking the process of detecting recapture events. Key results: Participants were able to successfully detect recapture events from small image pools based solely on a comparison of dorsal patterns. High consensus was reached on all matches included in the online survey, with the majority vote among participants representing the correct matching of individuals on all occasions. Conclusion: Our results indicate that there is sufficient intra-specific variability and temporal stability in dorsal patterning for it to be used as a reliable natural marker for identifying T. osbornei at the individual level. Implications: Our findings suggest that photo-CMR could be applied to other agamids with similar dorsal patterns, making it a potentially valuable tool and an alternative to artificial marking for monitoring wild populations of Australian lizards in the future.