Amphibians exhibit a great diversity of reproductive modes. Nevertheless, reproductive biology is still unknown for several threatened Neotropical species, including the Critically Endangered microendemic Valcheta frog, Pleurodema somuncurense. This paper looks at the reproductive biology of this species, describes its behavior, amplexus, spawning, clutches, embryonic development and breeding microhabitats, and discusses differences and similarities between it and the other Patagonian species included in the P. thaul clade: P. bufoninum and P. thaul. Fieldwork was conducted from 2013-2015 in the headwaters of Valcheta Stream (northern Patagonia, Argentina), over the whole known range of P. somuncurense. We also added information from an ex situ survival colony of this species. Pleurodema somuncurense has prolonged seasonal reproductive activity during spring-summer and presents features of both explosive and prolonged breeders. The Patagonian species of the P. thaul clade all have inguinal amplexus and lay pigmented eggs in gelatinous strings. During inguinal amplexus, the male P. somuncurense arches its body, bringing its vent closer to the female's, while contracting its body muscles rhythmically and moving its pelvic girdle up and down while the female spawns the eggs. We occasionally recorded mating calls, release calls, and warning vibrations. Although there are similarities among the three species, P. somuncurense has some specific features, such as scramble competition, which has not yet been recorded for any other species in the genus, and the mating call, although better records in natural conditions are needed for detailed analysis and more robust comparison. Because the breeding microhabitats used by P. somuncurense are currently under disturbance from livestock, their protection should be a matter of concern.
The expansion of the invasive rainbow trout Oncorhynchus mykiss into the thermal headwaters of Valcheta Stream (Patagonia, Argentina) and new predation records on the endangered endemic naked characin Gymnocharacinus bergii are presented here. These findings are discussed in relation to the contemporary evolution and thermal refuges hypothesis. This study has immediate implications for the conservation of G. bergii.
The Valcheta Frog, Pleurodema somuncurense (Cei, 1969), is a critically endangered species endemic from Somuncura plateau, Patagonia, Argentina. Although this frog is facing several human-related threats, the available information about its population status and trends is scarce. In order to update the range of the species, from 2013 to 2015, we conducted exhaustive surveys in all its geographical distribution, including sites never explored in the past. In 2014, we estimated occupancy and probability of detection with a three-visit survey in 40 sites of headwaters of Valcheta stream. Frogs were present in 58% of sites, and the probability of detection was high. We increased the known range of Valcheta Frog in 160%, by adding new sites occupied by the species. However, the status of the species remains of great concern, since its total range barely reaches 4 square kilometres.
ABSTRACT. The progressive exploitation and destruction of nesting habitat in recent years, combined with the substantial pressure from legal and illegal removal of wild nestlings and adults, justifies the development of a comprehensive study on the reproductive biology of the Turquoise-fronted Parrot (Amazona aestiva). We analyzed breeding parameters in a wild protected population of Turquoise-fronted Parrots in the Chaco forest, Argentina, examining variation among years, over the course of the breeding season, and in relation to the age of the nest. Mean clutch-size per nesting attempt was 3.68 eggs. Hatching success (proportion of eggs laid that hatch) was 0.73. Fledging success (proportion of nestlings that fledge) was 0.88. The overall breeding success (mean number of fledglings per laying female per year) was 0.95. Clutch size did not vary among years but it decreased with the delay of the nest initiation date. Hatching failure was the greatest cause of egg partial losses, and brood reduction was the main cause of nestling partial loses. Brood reduction was positively correlated with clutch size and with egg-laying date. We did not find interannual variation in any of the clutch or brood size variables. Our results showed that the population of Turquoise-fronted Parrots in the dry Chaco forest has high values of clutch size and nestling survival, and low values of hatching success. However, some aspects of the breeding biology need more attention, especially if the species continues to be harvested.Paramètres de reproduction de l'Amazone à front bleu (Amazona aestiva) dans la forêt sèche du Chaco RÉSUMÉ. L'exploitation et la destruction progressives de l'habitat de nidification advenues ces récentes années, combinées à la pression élevée de captures légale et illégale d'oisillons et d'adultes sauvages, justifient la mise en place d'une étude globale sur la biologie de reproduction de l'Amazone à front bleu (Amazona aestiva). Nous avons analysé les paramètres de reproduction d'une population sauvage protégée de cette amazone dans la forêt du Chaco, en Argentine, examinant les variations interannuelles, tout au long de la saison de reproduction, en relation avec l'âge du nid. La taille moyenne de la ponte par tentative de nidification était de 3,68 oeufs. Le succès d'éclosion (proportion d'oeufs pondus qui ont éclos) était de 0,73. Le succès à l'envol (proportion de jeunes qui ont pris leur envol) était de 0,88. Le succès de nidification d'ensemble (nombre moyen de jeunes à l'envol par femelle nicheuse par année) était de 0,95. La taille de la ponte n'a pas varié d'une année à l'autre, mais était plus faible lorsque la date d'initiation du nid était retardée. L'échec de l'éclosion était la cause la plus importante de perte partielle d'oeufs et une couvée réduite était la cause principale de perte partielle d'oisillons. La couvée réduite était positivement corrélée avec la taille de la ponte et la date de celle-ci. Nous n'avons pas observé de variations interannuelles des variables relatives à la taille de la...
Amphibian populations are declining globally. In this scenario, detailed information on their ecology is crucial to determine the status and extinction risk of their populations and, therefore, better plan conservation activities. The Valcheta frog Pleurodema somuncurense is a Critically Endangered species, which is endemic to the Valcheta Stream, Patagonia, Argentina. We assessed the status of this species at the metapopulation level, which we consider is a key step in planning management activities. We conducted visual encounter surveys from 2013 to 2019 to determine the distribution range of each local population of the Valcheta frog. During 2015, we also applied a capture-recapture survey to estimate the density and apparent survival of 1 local population. We used POPAN models for density estimation and the classic model of Cormack-Jolly-Seber to estimate apparent survival, using snout-vent length as a covariate. The metapopulation of the Valcheta frog is composed of 9 isolated local populations: 7 extant and 2 extinct. The extant populations have population sizes ranging from 243 to 4516 individuals. The small size of the smaller local populations makes their long-term viability in isolation unlikely. We found a positive correlation between the apparent survival and the snout-vent length of individuals. Our results showed that management strategies should be aimed at ensuring the long-term survival of this species, with a focus on the recovery of extinct populations, the restoration of disturbed habitats and the improvement of connectivity between local populations.
The sand-dune lizard Liolaemus multimaculatus is an Endangered species endemic to the Pampean coastal dunes of Argentina. To inform the development of a future Action Plan for this species, we investigated the demography and conservation status of all remaining populations, and we suggest management actions appropriate to local needs. We used population viability analysis to assess extinction risk in three inbreeding scenarios and estimate the minimum viable population and the minimum area requirement. To assess the current status of each local population, we used information related to population size, human pressure and connectivity. The results were then used to set and prioritize conservation management actions at local level. Our models indicated that populations of > 2,400 individuals would be viable in the long term and that inbreeding depression has a strong effect on extinction risk. The southern patches of coastal dune contain the largest populations of sand-dune lizards, and they are also better connected and less threatened. We suggest land protection as the priority management action for populations larger than the minimum viable population, whereas habitat recovery, when possible, should be the priority for patches of coastal dune smaller than the minimum area requirement. Supplementation with a small number of individuals could stabilize unviable populations but should be considered only in certain situations.The long-term conservation of the sand-dune lizard will be feasible only if a conservation action plan is developed and implemented.
Several methods were developed with the aim of prioritizing conservation efforts. However, most of these methods were focused on ranking areas for land protection, without offering alternatives for sites poorly ranked. We propose an alternative method that allows prioritizing conservation efforts independently of the status of a specific area. The conservation priorities method considers data related with biodiversity, availability of suitable habitat and human pressure, on area‐based units. This information is then standardized, obtaining a vector of three values, which reflects the situation of a specific area categorically (positive and negative) and quantitatively (how far from zero). Based on these values, specific conservation efforts can be settled at each area‐based unit. We tested this methodology on several political units located at the Pampean Coastal Dunes in Argentina, using herpetofauna as surrogate taxon. Our results confirm the needs of performing several conservation approaches to deal with Pampean Coastal Dunes' problems. The conservation priorities method showed to be a useful tool to characterize sites and to set conservation efforts based on its specific status, supplementing current methodologies.
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