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.

The Correlates of in Situ Larval Survivorship of the Threatened South American Toad Melanophryniscus montevidensis (Anura, Bufonidae)

“…Pond drying might intensify under global warming scenarios that would make more difficult for ponds to retain water for long periods of time (increasing densities, among other effects); this was previously suggested as an explanation for projected losses in distribution areas for several threatened Melanophryniscus species, especially M. montevidensis (Toranza and Maneyro, 2013;Zank et al, 2014). The in situ data provided by this study, combined with demographic data for terrestrial stages (Bardier et al, 2019), could be applied to population stage-structured models (e.g., Biek et al, 2002). These models could be constructed not only for M. montevidensis, but for ecologically similar congenerics, helping to understand the processes behind their declines and establish proper conservation actions for the populations and the ponds where they breed (Conroy and Brook, 2003).…”

“…Melanophryniscus montevidensis is an explosive breeder (sensu Wells, 2007) that exploits shallow ponds (less than 30 cm deep) formed over psamophilic vegetation after heavy rains, possibly during warm months (Alonzo et al, 2002;Pereira and Maneyro, 2016;Bardier et al, 2019). Breeding activity is mainly diurnal; males floating on the water surface or grasping aquatic vegetation start calling immediately after rains.…”

Reproductive Cycle, Size and Age at Sexual Maturity, and Sexual Dimorphism in the Stream-Breeding Frog Crossodactylus schmidti (Hylodidae)

“…La estimación precisa de las tasas de supervivencia y el tamaño de la población, son parámetros claves para entender la dinámica de las poblaciones, en condiciones naturales o en el escenario de cambio climático y alteración del hábitat (Pechmann, et al, 1991;Lebreton, et al, 1992, Williams et al, 2002. Estas estimaciones permitirán identificar la manera como los individuos responden a las fluctuaciones ambientales y los factores que tienen mayor sensibilidad sobre las tasas vitales (Molina -Zuluaga et al, 2013;Bardier et al, 2019).…”

“…Estimaciones de las tasas supervivencia para anfibios neotropicales solo están disponibles para unas pocas especies y se han centrado principalmente en la respuesta a la fragmentación (Steinicke, et al, 2018), variación temporal y entre clases de edad (Molina-Zuluaga et al, 2014;Loaiza -Piedrahita et al, 2016;Bardier, et al, 2019) o sobre en el efecto de quitridio (Ryan et al, 2008, McCaffery et al, 2013, manejo y conservación .…”

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)

“…Photo-ID techniques have been successfully applied in diverse zoological groups, including in amphibians (Speed, Meekan and Bradshaw, 2007;Bolger et al, 2012;Rocha, Carrilho and Rebelo, 2013;Andreotti et al, 2016;Amelon, Hooper and Womack, 2017). Although the utility of photo-ID for studies of amphibians has been recognized a long time ago (Hagström, 1973), the application of this method to individual colour patterns in CMR studies has only recently begun to rise for this group (Caorsi, Santos and Grant, 2012;Bendik et al, 2013;McCaffery, Richards-Zawacki and Lips, 2015;Morrison et al, 2016;Lampo, Señaris and García, 2017;Bardier et al, 2019).…”