The Critically Endangered El Rincon stream frog: Population viability and management actions in Patagonia, Argentina

Abstract

The El Rincon stream frog (Pleurodema somuncurense) is a microendemic species currently restricted to the thermal headwaters of the Valcheta Stream in the Somuncura Plateau, Northern Patagonia, Argentina. This species is listed as Critically Endangered on the IUCN Red List. The critical status of the El Rincon stream frog requires urgent management actions. Population viability analysis is one of the most effective tools to predict extinction risk and assess the potential effect of management actions. It is also helpful in knowing the minimum viable population (MVP) and minimum area requirements (MAR). However, this tool is rarely used to model viability in endangered amphibians. This work aimed to: (i) estimate the extinction risk of each local population of El Rincon stream frogs; (ii) estimate the MVP and MAR; and (iii) model reintroduction and supplementation of the population as management strategies for this species. Practical management actions are also suggested for each relict population. Population viability analyses were developed in Vortex 10.3.5.0 to estimate each local population's extinction risk, MVP and MAR. Supplementation and reinforcement of individuals were also modelled for local populations that are below the MVP. The estimated MVP was 430 individuals, while MAR reached 683 m2. Modelling of reintroducing individuals showed that a single reintroduction of at least 50 adults, 140 juveniles, or 1,000 tadpoles would be needed to achieve a viable population. Local populations below the MVP would benefit from supplementation of a pair of adult frogs every 17 to 20 years. This study provides a fundamental basis for assessing and improving current management and planning future conservation strategies within the framework of the El Rincon stream frog action plan.