Feeding ecology of endemic frogs of the Atlantic Forest in southern Brazil (original) (raw)
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Haddadus binotatus is an endemic anuran of the Brazilian Atlantic Forest and currently, there is no information about the diet of this species. We analyzed the diet of two populations of this anuran in two states in southeast Brazil. Samplings were carried out in 2004 in the state of Rio de Janeiro and in 2009 and 2010 in the state of Espírito Santo. Haddadus binotatus presented a rich diet composition, preying 19 prey types. Orthoptera, Coleoptera, and Blattodea were the most important preys in the Rio de Janeiro population, and Orthoptera, Araneae and Hemiptera were the most important in the Espírito Santo population. The diet composition differed numerically between the two localities, but not in terms of volume, which can reflect local differences in the prey availability in the two habitats. The jaw width limited the size of prey, which is expected for predators who swallow the preys without chewing. The proportion of individuals with empty stomachs was higher in the Rio de Janeiro population (39.2%) than in the Espírito Santo population (17.9%), suggesting that the former could be in a lower energy balance. The females of the species were larger than the males, which may result from the production of larger eggs.
Individual-level diet variation in four species of Brazilian frogs
Journal of Animal Ecology, 2009
Many natural populations exploiting a wide range of resources are actually composed of relatively specialized individuals. 2. This interindividual variation is thought to be a consequence of the invasion of 'empty' niches in depauperate communities, generally in temperate regions. If individual niches are constrained by functional trade-offs, the expansion of the population niche is only achieved by an increase in interindividual variation, consistent with the 'niche variation hypothesis'. 3. According to this hypothesis, we should not expect interindividual variation in species belonging to highly diverse, packed communities. 4. In the present study, we measured the degree of interindividual diet variation in four species of frogs of the highly diverse Brazilian Cerrado, using both gut contents and δ 13 C stable isotopes. 5. We found evidence of significant diet variation in the four species, indicating that this phenomenon is not restricted to depauperate communities in temperate regions. 6. The lack of correlations between the frogs' morphology and diet indicate that trade-offs do not depend on the morphological characters measured here and are probably not biomechanical. The nature of the trade-offs remains unknown, but are likely to be cognitive or physiological. 7. Finally, we found a positive correlation between the population niche width and the degree of diet variation, but a null model showed that this correlation can be generated by individuals sampling randomly from a common set of resources. Therefore, albeit consistent with, our results cannot be taken as evidence in favour of the niche variation hypothesis.
Zoologia, 2011
Habitat reduction and degradation, especially in tropical forest areas, has caused a worrisome global loss of species (BENÍTEZ-MALVIDO & MARTÍNEZ-RAMOS 2003, GARDNER et al. 2007, TODD & ANDREWS 2007). The Brazilian Atlantic Forest has a high biodiversity and high endemism rates, sheltering approximately 7% of the world's plant and animal species. Due to human action, it is among the most threatened biomes, with only about 12% of the original area remaining (QUINTELA 1990, MYERS et al. 2000, RIBEIRO et al. 2009). Regarding amphibians, Brazil is the most species rich country, reaching almost 900 recognized species (SBH 2010). Only in the Atlantic Rainforest Biome, there are more than 400 registered amphibian species, with most of them endemic to this biome (HADDAD et al. 2008). Several studies carried out in different tropical forests throughout the world provide data on richness, composition and density of frogs living on the leaf-litter layer of the forest floor (e.g.,
Documenting elevational gradients in species richness is important to understand the determinants of spatial distributions. We studied anuran richness along an elevational gradient in an Atlantic Rainforest area to evaluate i) how anuran richness and elevation are related; ii) if the data support the hypothesis of the mid-domain effect or the Rapoport effect and iii) if there is seasonal variation in species richness and abundance of leaf litter anurans in the studied site. Sampling was carried out using time-constrained visual encounter surveys and plot (quadrat) methods at six elevational levels. We found 406 individuals belonging to 19 anuran species. The most abundant frog species were Ischnocnema parva (6.2 individuals per 100 m 2) and Adenomera marmorata (2.0 individuals per 100 m 2). The overall leaf litter frog abundance was 11.2 ind/100 m 2 , with highest values at 150 m (26.6 ind/100 m 2) and 300 m (25.6 ind/100 m 2) elevations. We found high species turnover across altitudes. Our data neither supported the mid-domain effect nor the elevational Rapoport effect. There was no significant difference in frog abundance among seasons, although most of the leaf litter frogs species were found in the wet season (235 individuals or 69.3%). Our study demonstrates a high local frog species richness and abundance in combination with an abundance decreasing with elevation.
Biota Neotropica, 2022
Among amphibian species from high elevation areas in the Brazilian Atlantic Forest there is a high percentage of threatened and endemic species, but there is still a relative scarcity of local inventories for these organisms. Here, we present data on anuran composition, relative abundance and estimated densities for leaf-litter frogs from an Atlantic Forest area within the APA Serra da Mantiqueira, in Rio de Janeiro state, Brazil, based on results of a short-term survey carried out at altitudes of 1,350-1,750 m, in November 2005 (with additional records from surveys made in 2010 and 2011). Three sampling methods were used during the 2005 survey: plot sampling, visual encounter surveys (VES; performed during the day, at the dusk, and at night), and pitfall traps with drift fences; only non-standardized visual searches were employed during the 2010 and 2011 surveys. We recorded 24 species, with the direct-developer Ischnocnema sp. (gr. lactea) being the most abundant. Most anurans (90% of all individuals) sampled by VES were captured during the crepuscular and nocturnal periods. The estimated density of the local leaf-litter frog assemblage based on plot sampling was 18.4 ind/100 m 2 , which is one of the highest values currently reported for Atlantic Rainforest areas. This is the first study analyzing the anuran fauna composition of an Atlantic Forest area within the APA Serra da Mantiqueira and adds to the body of knowledge on the fauna of the southern region of Rio de Janeiro state.
Zoologia, 2009
Data on species composition, richness, and density are presented for the leaf litter frog assemblage of an area of Atlantic Rainforest at the Serra dos Órgãos mountain range, in the state of Rio de Janeiro, southeastern Brazil. Three sampling methods were used: plot sampling, visual encounter surveys, and pitfall traps. The local assemblage of leaf litter frogs was composed of 16 species, with the direct-developing species, Euparkerella brasiliensis (Parker, 1926), being the most abundant. The estimated density of the local leaf litter frog assemblage based on plot sampling was 17.1 ind/100 m2 and the estimated overall leaf litter frog mass was 684.2 g/ha. The estimated density of leaf litter frogs at the present study is the highest currently reported for Atlantic Rainforest areas, which reinforces the idea of higher densities of leaf litter frogs in the Neotropical Region compared to the Old World tropics.
Journal of Natural History, 2020
We studied several ecological aspects of the endemic Ololygon kautskyi in the Reserva Biológica Duas Bocas (RBDB), Espírito Santo, Brazil, including activity, detectability and use of microhabitats. Fieldwork was carried out from February 2018 to March 2019, between 8:00 and 23:00, in 22 transects of 50 m along streams. For each individual frog found, we recorded the hour, the microhabitat in which it was detected, the height above ground, snout-vent length (in mm), and mass (in g). We measured the air temperature (°C), relative humidity (%), stream water temperature (°C), pH, and conductivity. We tested for differences in body size among sexes and estimated the detectability of the species in relation to the environmental variables. We recorded a total of 93 individuals from O. kautskyi, with the majority of individuals recorded between 18:00 and 22:00. Females were significantly larger in body size than males. The detection probability of the species was affected by the period of the day, air temperature and relative air humidity. Ololygon kautskyi used five different types of microhabitats, and vegetation was the most used microhabitat by the species. We conclude that O. kautskyi is nocturnal, mainly uses vegetation on stream banks, is more likely to be detected during cold and dry days, and is dimorphic in body size with females being larger than males. There is currently insufficient information to assess the conservation status of O. kautskyi. However, considering that the species is endemic to a relatively small portion of the Atlantic Forest biome in the state of Espírito Santo and that its ecology is strongly associated with riparian zones, we believe that the species would be eligible to be categorised in some threat category.
Frog diversity in the Floresta Nacional de Chapecó, Atlantic Forest of southern Brazil
Biota Neotropica, 2008
The Atlantic Forest is considered one of the world's biological diversity hotspots but is nevertheless increasingly threatened with the rapid destruction and fragmentation of its natural areas. In the state of Santa Catarina, southern Brazil, remnants of the mixed ombrophilous forest and seasonal deciduous forest exist as islands within large areas of agriculture, pastures and human settlements. Here we present information on species richness and habitat use by anurans in the Floresta Nacional de Chapecó, located in the western portion of the state of Santa Catarina. Anurans were surveyed by active search of potential reproductive sites from December 1998 to December 2001. A total of 29 species were recorded, most of which have a known distribution restricted to southern Brazil and adjacent countries (Argentina, Paraguay, and Uruguay) and use open areas for reproduction. The species composition was most similar to other areas of mixed ombrophilous forest and seasonal deciduous f...
South American Journal of Herpetology, 2008
We evaluated the effect of environmental and spatial variables on the distribution of 11 species of anurans in 10,000 ha of nonflooded forest in central Amazonia. Diurnal and nocturnal frog assemblages were sampled in 72 plots using visual and auditory surveys. Distance from stream was the best predictor for species richness and abundance, with an increase in distance resulting in a decrease in number of species and individuals. Three species (Osteocephalus oophagus, Trachycephalus resinifictrix and Vitreorana oyampiensis) were not influenced by environmental predictors and occurred along all environmental gradients. The watersheds did not influence the abundance of the majority of species except Allobates sp., Atelopus spumarius and Leptodactylus rhodomystax. Our results indicate that most species studied occur along the margins of streams, which they also use as dispersal corridors. The removal of forests near streams could lead to local extinctions.