Traditional methods for identifying individual amphibians in capture-markrecapture (CMR) studies have been primarily confined to post-metamorphic stages, using artificial markers that come with a variety of limitations. An alternative that may open CMR studies to earlier life stages involves the use of a species' natural external markers in photo-based identification. In this study, we investigated whether it was possible to distinguish tadpoles of the threatened green and golden bell frog (Litoria aurea) at the individual level based on tail venation patterns. We collected photographs of the tails of captive-raised tadpoles using a smartphone over a 4-week period. This photo-library was used to create an electronic survey where participants were asked to detect matches for query tadpoles from small image pools. We found that most participants agreed on a match for each query, with perfect consensus achieved for most queries (83%). We detected a 14% decline in perfect consensus when participants were asked to match images of tadpoles separated by longer time intervals, suggesting that it is more difficult to visually identify recapture events of L. aurea tadpoles over extended periods due to changes to tail appearance. However, consensus was obtained by participants for all queries, with all matches verified as being correct by the primary researcher. The strength of agreement among participants with no prior experience in matching tadpole tails suggests that there is sufficient inter-individual variation in this feature for individuals to be manually identified. We thus propose that photo-identification is likely to be a valid, non-invasive technique that can be used for short-term studies on tadpole populations that display tail venation. This offers an alternative to artificial markers that may not allow for individual identification, while also opening up tadpole monitoring programmes to citizen scientists who can be recruited online to process image data from home.

Individuals within amphibian populations are commonly identified using artificial marking techniques, such as toe clipping and microchipping. However, many species in this group may be strong candidates for visual identification from photographs given intraspecific variability in skin features. We investigated the potential for dorsal skin patterns to be used as natural markers for the photo‐identification of both juveniles and adults of the green and golden bell frog (Litoria aurea). This is a threatened species that has come under intense population monitoring using capture‐mark‐recapture procedures primarily involving the use of artificial markers, with no apparent investigation of the potential for natural markers to be used instead. We collected photographs of marked individuals to determine the level of intraspecific variability in dorsal patterning within a population. This photo‐database was subsequently used to create an online survey in which participants were asked to match separate images of query frogs from small image pools by comparing dorsal patterns. Photographs were taken on a smartphone device under field conditions to test whether this technique could be applied to the study of wild populations with little cost or expertise required. We showed that dorsal patterns are clear and distinct among L. aurea individuals and easily visualised from field‐acquired images to detect recapture events by eye with a low error rate. While an overwhelming majority of adults possessed dorsal patterning that can be easily distinguished by eye, juveniles often showed a complete absence of patterning, suggesting that photo‐identification may be more effective for adult stages. Nevertheless, we highlight the feasibility of collecting visual information on the natural markings of a threatened anuran, providing evidence that it may be used as a supplementary form of identification alongside more traditional techniques, highlighting a potential direction for the future monitoring of this species.

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