Estimating Population Size and Survival for Two Subpopulations of the Critically Endangered Patagonia Frog, Atelognathus patagonicus, in Laguna Blanca National Park, Argentinian Patagonia

Abstract

Detailed knowledge of population dynamics and species status is essential for effective conservation planning. The Critically Endangered Patagonia frog Atelognathus patagonicus inhabits small, isolated lagoons in north-western Argentinian Patagonia. Using capture–mark–recapture techniques over two consecutive summer seasons (2023–2024), we estimated the abundance and survival of two subpopulations in the Antiñir and Jabón lagoons within Laguna Blanca National Park. POPAN models estimated abundances of 2937 (95% CI: 2089–4368) individuals in Antiñir and 5605 (95% CI: 4547–7041) in Jabón, including all life stages. Cormack–Jolly–Seber models revealed an apparent juvenile survival of 0.988 (95% CI: 0.981–0.993) in Antiñir, and the value ranged from 0.865 (95% CI: 0.627–0.939) to 0.966 (95% CI: 0.954–0.975) in Jabón. Adult survival was estimated at 0.956 (95% CI: 0.932–0.972) in Antiñir and 0.969 (95% CI: 0.923–0.988) in Jabón. We found albino individuals only in Antiñir, comprising 5% of the subpopulation, with an apparent survival of 0.956 (95% CI: 0.4–0.999) across all stages. Our findings suggest early signs of recovery following recent severe droughts. However, expanding monitoring efforts to additional lagoons, particularly those outside the protected area, is crucial to the assessment of broader recovery trends. This study provides a valuable foundation for comparing population dynamics across subpopulations and developing targeted conservation strategies to ensure the long-term protection of this species.