Feasibility of Using Computer-Assisted Software for Recognizing Individual Rio Grande Cooter (Pseudemys gorzugi)

Mark-recapture methods used in population demography studies involve marking of animals, such as tagging, notching, and tattooing. These techniques are invasive and potentially harmful to the animals. Photo-identification using natural animal markings is less invasive and has become more widely used for a range of taxa including invertebrates, fishes, reptiles, amphibians, and mammals. During 2016 and 2017, we studied the demographics of the Rio Grande Cooter (Pseudemys gorzugi) using traditional mark-recapture techniques (i.e., shell notching and toe clipping). However, P. gorzugi displays plastral marks that could potentially be used for individual recognition. Because the photo-identification process ‘by-eye' is time consuming, we tested the efficiency of three pieces of software, I³S Pattern⁺, Wild.ID, and APHIS, for individual identification of P. gorzugi using plastron pattern. Matching results of each program were generated into ranks with the 1^st rank being the most likely match. Within the top 20 ranked images, Wild.ID yielded the highest number of correct matches (83.87%), followed by APHIS (ITM; 69.35%), APHIS (SPM; 67.74%), and I³S Pattern⁺ (61.29%). We found the quality of photos significantly contributed to the software effectiveness; however, turtle age and plastron wear did not affect the accuracy of the photo-identification software. We concluded that Wild.ID can be used as a non-invasive photo-recognition technique for P. gorzugi in a short-term population study.