Computer-aided pattern recognition of large reptiles as a noninvasive application to identify individuals

For large species, the capture and handling of individuals in capture-mark-recapture studies introduces nonhuman animal welfare issues associated with handling, physical marking, and possible wounding due to tag loss. The use of photographic identification for these species offers an alternative and less invasive marking technique. This study investigated the opportunity offered by photo identification to individually mark individuals of a large reptile, the perentie (Varanus giganteus), in Australia and therefore avoid the stress of physically capturing and handling. Photographs submitted by a remotely located community were first validated to confirm whether perenties could be individually identified from their spots electronically using a computer program. Computer-aided selection of unique patterns was found to be appropriate for the identification of individuals and confirmed 38 individuals during the sampling period. The value of this approach is 2-fold: There is a benefit to animal welfare in that handling an animal is not required to capture him or her, thus reducing capture-related stress; and confirmation that photo identification of distinctive patterns of the perentie is valid and offers a useful option to identify individuals of this large species.