Seasonal demography of the threatened Montevideo Redbelly Toad (Melanophryniscus montevidensis) in a protected area of Uruguay

Abstract

Estimates of demographic parameters are scarce for Neotropical amphibians, a concerning fact because this region has the highest proportion of threatened amphibians in the world. We conducted a 3-year study where we applied a robust capture–mark–recapture design to assess the importance of breeding and non-breeding activity patterns over the survival rates, detection probabilities, and abundances of the Montevideo Redbelly Toad (Melanophryniscus montevidensis (Philippi, 1902)), a threatened anuran from Uruguay. The best models grouped seasons into hot and cold periods cyclically, were state-dependent in transition probabilities, and were time-dependent in detection probabilities for adults, but had constant detection probabilities for juveniles. Averaged estimates suggest a high survivorship rate during cold seasons (above 80%), but lower probabilities (below 60%) during hot seasons, especially for males. Analogously, the non-breeding activity had a seasonal pattern, with higher activity during spring and higher sheltering rates during autumn. These activity rates negatively influenced the averaged survivorship rates of adult males and females. Long-term (matrix) projections of seasonal survivorships, along with assessments of the causes of these patterns, should be carried out to determine extinction probabilities and possible threats for the conservation of the genus Melanophryniscus.