Can you identify a numbat by its stripes? Optimising identification of individuals of a threatened mammal from camera trap images

Camera trap images have been used to identify individual mammals that have unique pelage patterning, but details on how identification was achieved are often omitted, limiting reproducibility. Developing standardised frameworks for individual identification of mammals would greatly enhance rigour and consistency. The numbat ( Myrmecobius fasciatus ) is one such species where individual identification has been conducted, but details on how this was done were limited. Using images from four camera trap surveys conducted on an agricultural property in southwestern Australia, this study assessed the extent of variation and reliability of pelage features, and the extent to which putative individuals can be reidentified over time in the numbat. We also examined how individual identification can be used to track numbat movements and site fidelity relative to den logs in remnant vegetation. We successfully identified individual numbats using 16 phenotypic variables. Left and right flank stripe number and dorsal stripe patterning exhibited the greatest inter-individual variation and were consistently discernible in a high proportion of images. Putative individuals could be redetected after 2.5 years, providing circumstantial evidence of pelage pattern stability in adult numbats. We further demonstrated that distinct groups of individuals preferentially used different remnant vegetation patches and den logs. Our results explicitly define features best used for identification of individual numbats and highlight the importance of remnant vegetation and high den log availability for sustaining diverse numbat populations. This research illustrates the importance of developing systematic frameworks for establishing photo identification as a tool for examining mammal ecology.