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)

Abstract

<jats:title>Abstract</jats:title> <jats:p>The use of individual phenotypic features as non-invasive marks through photo-identification (photo-ID) has many advantages for individual-based field studies. However, since error rates vary between species, matching techniques, and image qualities, it is important to assess error rates to evaluate the reliability of photo-ID. We tested the performance of this method in the Pacific Horned Frog, <jats:italic>Ceratophrys stolzmanni</jats:italic>, a threatened anuran with a variable dorsal coloration. We compared the effectiveness of visual (i.e. human recognition) <jats:italic>versus</jats:italic> software-assisted recognition techniques (Wild-ID and APHIS), and assessed the potential applicability of these techniques to identify post-metamorphic individuals (froglets). The three techniques differed in their performance. The visual technique was the only one to produce type I errors between pairs of images (i.e. matching images which are not true matching pairs), however it also produced fewer type II errors (i.e. not identifying true matching pairs of images) than the software-assisted techniques. For froglets, we found that similarity scores calculated by photo-ID software did not differ significantly between groups of froglets and older individuals, supporting the idea that colour patterns in this species remain stable after metamorphosis. The lack of type I errors and the substantial reduction in required time achieved through the use of software, make software-assisted techniques (particularly Wild-ID) a valid and convenient matching technique for <jats:italic>C. stolzmanni</jats:italic>. We propose that photo-ID can also be applied to froglets of this species, since the pattern at this stage appears to be as variable as in adults and maintained through life.</jats:p>

Nesting Ecology of Lepidochelys olivacea in Lobito, Angola

“…The utilization of photographs for individual identification is a tool that is considered advantageous [ 75 ] due to its non-invasiveness, stress reduction, and pain alleviation [ 76 ] as opposed to invasive tagging methods [ 77 ]. Coupled with available artificial intelligence, several studies have been conducted to explore the fidelity of these tools and their capacity to accurately identify individuals during mark–recapture events [ 78 ].…”

Re-identification of individuals from images using spot constellations: a case study in Arctic charr (Salvelinus alpinus)

“…Although the quality of photographs and phenotypic measures of interest will also have an impact on methods, removing the need to tag individuals post-capture would be beneficial in many cases (e.g. [ 41 ]). Therefore, as a tool for improving confidence in individual identification data without dramatically increasing the human-driven processing time, this method of photo-ID could prove useful.…”

Natural history of the marsupial frog Gastrotheca albolineata (Anura: Hemiphractidae) in lowland Brazilian Atlantic Forest

“…Lama et al 2011, Caorsi et al 2012. We counted only adults in the census to avoid possible ontogenetic changes in the natural markings of juvenile frogs (Bardier et al 2020). We visually identified each photographed individual, adding it to the image database and assigning it a number (for example, ID01_ date).…”