Performance of visual vs. software-assisted photo-identification in mark-recapture studies: a case study examining different life stages of the Pacific Horned Frog (Ceratophrys stolzmanni)

What is it about?

The use of morphological features for the identification of individuals, like taking pictures of skin colour patterns (photo-identification: photo-ID), is an example of a non-invasive marking method for studying populations in an individual-based approach. This is key for amphibians, who have been historically been studied using methods that harm the individuals to mark them. Our study addressed the applicability of photo-ID to a population of a Neotropical threatened species in a protected area. So, population studies constructed using the recapture information from our study would provide important insights towards its conservation._x000D_ However, photo-ID methods have their own difficulties: errors in these methods can lead to significant bias in population studies. Indeed, different manual or software-aided photo-ID can have different errors. Also, colour patterns of froglets can change through time; a serious obstacle for the application of photo-ID in early stages. We tested different methods and measured their errors, and we introduced a simple method to estimate, without having recaptures, if photo-ID can be applicable to froglets. Our findings support that photo-ID is trustable for individual recognition at all life stages, and which method is more appropriate for this species. This is important for population studies of C. stolzmanni, but our procedures can be easily replicable in future assessments of the performance of photo-ID in amphibian species.

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