The Population Decline and Extinction of Darwin’s Frogs

Abstract

Darwin’s frogs (Rhinoderma darwinii and R. rufum) are two species of mouth-brooding frogs from Chile and Argentina. Here, we present evidence on the extent of declines, current distribution and conservation status of Rhinoderma spp.; including information on abundance, habitat and threats to extant Darwin’s frog populations. All known archived Rhinoderma specimens were examined in museums in North America, Europe and South America. Extensive surveys were carried out throughout the historical ranges of R. rufum and R. darwinii from 2008 to 2012. Literature review and location data of 2,244 archived specimens were used to develop historical distribution maps for Rhinoderma spp. Based on records of sightings, optimal linear estimation was used to estimate whether R. rufum can be considered extinct. No extant R. rufum was found and our modelling inferred that this species became extinct in 1982 (95% CI, 1980–2000). Rhinoderma darwinii was found in 36 sites. All populations were within native forest and abundance was highest in Chiloé Island, when compared with Coast, Andes and South populations. Estimated population size and density (five populations) averaged 33.2 frogs/population (range, 10.2–56.3) and 14.9 frogs/100 m2 (range, 5.3–74.1), respectively. Our results provide further evidence that R. rufum is extinct and indicate that R. darwinii has declined to a much greater degree than previously recognised. Although this species can still be found across a large part of its historical range, remaining populations are small and severely fragmented. Conservation efforts for R. darwinii should be stepped up and the species re-classified as Endangered.

Influence of Anthropogenic Disturbances on Stand Structural Complexity in Andean Temperate Forests: Implications for Managing Key Habitat for Biodiversity

“…Coarse woody debris (CWD) increases structural complexity [2,86], having a positive effect on forest biodiversity [55,56,87]. Our results concurs with previous studies reporting that the volume of CWD tends to accumulate in less disturbed habitats [8,19,87,88].…”

Effects of amphibian phylogeny, climate and human impact on the occurrence of the amphibian‐killing chytrid fungus

“…Sites were chosen on the basis of having amphibian populations, good accessibility, and that contributed to a good coverage of the whole study area. In each, a search effort of one hour by two researchers was conducted using a standardized methodology, as previously described (Soto‐Azat et al ., ,b). In each locality, we performed exhaustive searches across land and aquatic environments and recorded the altitude and geographic coordinates.…”

“…In recent years, evidence for the critical involvement of EIDs in the amphibian decline phenomenon has grown and become more convincing, especially in the case of amphibian chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis ( Bd ). This disease has been associated with amphibian population declines at the global scale and is implicated in the extinction of several amphibian species from Australia, Costa Rica and Chile (Pounds et al ., ; Daszak et al ., ; Lips et al ., ; Pounds et al ., ; Schloegel et al ., ; Skerratt et al ., ; Bielby et al ., ; Wake & Vredenburg, ; Collins & Crump, ; Soto‐Azat et al ., ,b). Less than two decades exist for Bd investigation (Berger et al ., ; Longcore et al ., ), and although a substantial amount of research has been accomplished, several aspects of its basic biology, epidemiology and interaction with their hosts are still unknown (Kilpatrick et al ., ).…”

A new species of Scinax from the Purus-Madeira interfluve, Brazilian Amazonia (Anura, Hylidae)

“…Recent studies warn that one third of the PMI rainforest will be lost as a consequence of massive logging if this road improvement scheme goes ahead (Maldonado et al 2012). Habitat loss has been widely reported as the major cause for populations decline and local extinctions for many groups of organisms, including frogs (e.g Soto-Azat et al 2013). Therefore, current need of conservation of PMI is more urgent than ever before.…”