Amphibian Abundance Research Articles

Farming practice affects rice field animal biota during cultivation but not fallow periods in Taiwan

AbstractRice is one of the most important staple foods in the world, with irrigated rice paddies largely converted from natural wetlands. The effectiveness of rice fields in preserving species depends partially on management practices, including the usage of pesticides. Previous studies have focused predominantly on the cultivation period, leaving the potential effects of soil pesticide residues on organisms during the fallow periods underexplored. Other animals, such as waterbirds, also rely on aquatic invertebrates in flooded fallow fields for their survival. We investigated vertebrates and macroinvertebrates during cultivation and fallow periods in organic and conventional rice fields in Taiwan. The association of environmental factors with terrestrial and aquatic organisms was also analyzed. In total, 32,880 individuals from 144 invertebrate families and 381 individuals from 15 vertebrate families were recorded after nine samplings each in six organic and six conventional rice fields. The family richness and abundance of all invertebrates were higher in organic than in conventional fields during the cultivation period but were similar in fields under either agricultural practice during the fallow period. The differences in richness and abundance of terrestrial invertebrates between the two practices increased with progression of rice cultivation, while there was no difference in abundance of aquatic invertebrates during the fallow period. The richness and abundance of fish, amphibians, reptiles, birds, and migratory waterbirds were not statistically different between the two practices. Our study suggested accumulative effects of pesticides on suppressing terrestrial and aquatic invertebrates during the cultivation period, but no negative effects of soil pesticide residues on aquatic invertebrates during the fallow period. This comprehensive study provided a holistic picture of macroinvertebrate and vertebrate fauna, as well as the potential ramifications of pesticide usage, in a representative Southeast Asian rice paddy ecosystem. Future studies should compare rice fields with natural wetlands to better assess how to capitalize on agroecosystems for biodiversity conservation.

How plants affect amphibian populations.

Descriptions of amphibian habitat, both aquatic and terrestrial, often include plants as characteristics but seldom is it understood whether and how those plants affect amphibian ecology. Understanding how plants affect amphibian populations is needed to develop strategies to combat declines of some amphibian populations. Using a systematic approach, we reviewed and synthesized available literature on the effects of plants on pond-breeding amphibians during the aquatic and terrestrial stages of their life cycle. Our review highlights that plant communities can strongly influence the distribution, abundance, and performance of amphibians in multiple direct and indirect ways. We found three broad themes of plants' influence on amphibians: plants can affect amphibians through effects on abiotic conditions including the thermal, hydric, and chemical aspects of an amphibian's environment; plants can have large effects on aquatic life stages through effects on resource quality and abundance; and plants can modify the nature and strength of interspecific interactions between amphibians and other species - notably predators. We synthesized insights gained from the literature to discuss how plant community management fits within efforts to manage amphibian populations and to guide future research efforts. While some topical areas are well researched, we found a general lack of mechanistic and trait-based work which is needed to advance our understanding of the drivers through which plants influence amphibian ecology. Our literature review reveals the substantial role that plants can have on amphibian ecology and the need for integrating plant and amphibian ecology to improve research and management outcomes for amphibians.

TERRESTRIAL AMPHIBIANS INHABITING AN URBAN XERIC ECOSYSTEM: AN ASSESSMENT OF FROGS AND SALAMANDERS IN PROTECTED AREAS FROM MEXICO CITY

Amphibians are particularly sensitive to disturbances caused by urbanization. Urban disturbances impact amphibians at different ecological scales that include a decrease in biodiversity, increment of stress, and changes in vocal behavior. However, little is known about urban effects on terrestrial amphibians. In this study, we quantified abundance (by encounter rates) and species richness of amphibians, and the characteristics of their habitats in Pedregal del Xitle, a xerophytic ecosystem in Mexico City. In addition, we evaluated the vocal activity of Pedregal frogs under different noise exposures within the three protected areas. During 2015 and 2016 with the support of volunteers, several stratified direct night searches were conducted in three urban protected areas. Additionally, using a non-supervised classification of satellite images, we analyzed the coverage of the different vegetation types, and calculated the evenness of amphibians. With an effort of 238 person-hours, we located 73 individuals of amphibians, including three plethodontid salamanders (Aquiloeurycea cephalica, Chiropterotriton orculus and Pseudoeurycea leprosa), and the Pedregal frog, Eleutherodactylus grandis. Altogether, the captures of C. orculus and E. grandis represented 90% of the amphibians found. We found that 75% of the amphibians occupied the rocky ground microhabitat. The call rate of E. grandis was consistently lower at sites with the highest noise exposure. Among the three urban protected areas, Ecoguardas stands out as the one with the greatest abundance and diversity of amphibians and the largest proportion of forested area. Our study revealed the ecological value of the Pedregal ecosystem for terrestrial amphibians, since the most threatened species (the frog E. grandis and the salamander C. orculus) are those with the greatest presence in the urban protected areas studied.

Using biodiversity response for prioritizing participants and service provisions in a payment-for-water-storage program in the Everglades basin

Hydrological changes can lead to biodiversity responses that are complex and challenging to quantify. We present a framework that uses biodiversity as a criterion to address “where to buy” and “how much to buy” in a payment-for-environmental-services (PES) program focused on water storage service in the Everglades basin, USA. The PES program was designed to pay for added water storage on private cattle ranchlands by raising the spillage level in drainage control structures to reduce surface flows. We predicted that increased hydration of previously drained wetlands would benefit biodiversity, a previously unquantified but desirable co-benefit of the original program, and that a PES program offering bundled services (e.g., storage and biodiversity) can better achieve restoration goals. We quantified desirable biodiversity services (abundance of native flora and fauna such as cover of wetland and forage plants, and abundance of fishes, amphibians, and macroinvertebrates), dis-services (e.g., abundance of invasive plants and mosquitos), and hydrologic signatures (e.g., wetland water depth, inundation area and duration) at four ranches to develop eco-hydrological relationships (models) between hydrological changes and biodiversity responses. Next, a hydrologic model (MIKE-SHE/MIKE-11) was used to predict surface and subsurface water levels and flows and resulting wetland hydrologic signatures for 13 water storage alternatives on the ranches, which were used as example PES proposals. A decision-support-system (DSS) was developed to integrate (i) storage predicted by the hydrologic model, (ii) biodiversity responses predicted by eco-hydrologic models, and (iii) a user-defined preference scheme to assign importance weights to storage, biodiversity, and implementation cost. The DSS calculated a cumulative score for ranking PES proposals. By considering desirable services and dis-services, stakeholders can decide on their preferred level of services, e.g., buyer(s) may settle for less storage if there is a gain in desirable biodiversity. The DSS can identify trade-offs among services, helping stakeholders negotiate.

Riparian buffer effects on headwater-stream vertebrates and habitats five years after a second upland-forest thinning in western Oregon, USA

Riparian-management zones protect aquatic species and their habitats in managed forests, yet the effects of riparian-management alternatives warrant further study. We examined effects of alternative riparian-buffer widths on fish and amphibians in small headwater streams with upland forest thinning in western Oregon, USA. Previously, we reported apparent lag-time effects developing 10 years after thinning of upland second-growth forest, and additional effects 1–2 years after a second-thinning harvest. Here, we analyze effects on fish and amphibian abundances, body-size metrics, and habitats 5 years after the second thinning at 58 stream reaches across eight study sites. Riparian-buffer effects were evident for several species and species groups: higher densities of fish and amphibians (e.g., coastal giant salamander [Dicamptodon tenebrosus], torrent salamanders [Rhyacotriton spp.], sculpins [family Cottidae]) were detected in reaches with a no-entry one site-potential tree-height buffer (∼70 m wide) in comparison with lower densities in two narrower no-entry buffers (6-m-wide, and a variable-width buffer with a 15-m minimum width) and a thin-through managed buffer (two site-potential tree-heights wide, ∼140 m). In addition, indicator-species analyses showed that torrent salamander densities were positively associated with stream reaches in unmanaged controls. Some amphibians changed habitat affinities slightly, being found during the most-recent sampling in locations with habitats related to larger stream sizes (i.e., more-perennial stream flows) than they had been in earlier sampling. Analyses of body-size metrics showed associations with buffers across 42% of species × post-treatment years analyzed, yet patterns were inconsistent within species, and more consistent associations of body metrics were found with microhabitat types, finding larger animals in pools. Although the mechanism driving changes is unclear, the positive associations of species’ densities with one-tree buffers suggest that either lag-time or cumulative effects of factors associated with treatments are developing, with benefits of wider streamside protections over longer time periods for headwater-associated fish and amphibians. Our findings of higher densities of headwater-reliant Rhyacotriton species in stream-reach treatments with the one-tree buffers, and affinities with unthinned control reaches, support the benefits of greater headwater-stream protections for that species complex, which includes species of conservation concern. The mix of different buffer widths and unmanaged units across our eight sites may be promoting site-scale persistence of a community of aquatic-vertebrate species—a mix of buffer widths with upslope forest management may be an alternative for larger-scale riparian forest-management objectives.

Random placement models explain species richness and dissimilarity of frog assemblages within Atlantic Forest fragments.

Understanding the effects of random versus niche-based processes on biodiversity patterns is a central theme in ecology, and an important tool for predicting effects of habitat loss and fragmentation on biodiversity. We investigated the predictive power of random processes to explain species richness and species dissimilarity of amphibian assemblages in a fragmented tropical landscape of the Atlantic Forest of South America. We analyzed a large database of amphibian abundance and occupancy, sampled in 21 forest fragments ranging in size from 1.9 to 619ha. We compared observed species richness and species dissimilarity with the outcomes of two null (random placement) models: 1- the traditional Coleman's area-based model and 2- an abundance-based model (based on the number of individuals observed in each fragment). We applied these models for all species combined, and separately for forest-dependent and habitat-generalist species. The abundance-based model fitted the observed species richness data better than the area-based model for all species, forest-dependent species, and generalist species. The area-based and the abundance-based models were also able to significantly explain species dissimilarity for all species and for generalists, but not for forest dependent species. The traditional area-based model assigned too many individuals to large fragments, thus failing to accurately explain species richness within patches across the landscape. Although niche-based processes may be important to structuring the regional pool of species in fragmented landscapes, our results suggest that part of the variation in species richness and species dissimilarity can be successfully explained by random placement models, especially for generalist species. Evaluating which factors cause variation in the number of individuals among patches should be a focus in future studies aiming to understand biodiversity patterns in fragmented landscapes.

Diversity of herpetofauna at restored cranberry bogs: A comparative survey of herpetofaunal diversity at a restored wetland in comparison to a retired cranberry bog to assess the restoration success

Wetlands perform critical ecological functions and provide wildlife habitats. Yet, wetland degradation continues at a global scale. In Massachusetts, USA, wetland restoration has reached remarkable heights, partly promoted by the retirement of cranberry bogs. In this study, to assess the effectiveness of cranberry-farm restoration for conservation of native herpetofauna, we surveyed both retired and restored cranberry bogs in south-eastern Massachusetts. Using both visual encounter surveys and baited aquatic traps, we documented herpetofaunal species and their relative abundance. Both survey methods combined, the cumulative herpetofaunal species richness at the restored bogs (16) exceeded that of the retired bogs (11). Our trap surveys indicated that the amphibian species richness at the retired bog was significantly greater than that of the restored bog. In contrast, reptilian species richness as well as the relative abundance of both amphibians and reptiles were significantly greater at the restored bog compared to the retired bog. Subsequent analyses we performed identified that greater habitat heterogeneity emerging from active restoration intervention was the underlying driver of elevated richness and abundance. Most frequently encountered herpetofauna at the restored versus retired bogs were habitat generalists with broader geographic ranges and are not of conservation concern. Our findings suggest that the restored bog we monitored is still in the early-recovery phase after active intervention. We urge the need for long-term herpetofaunal inventories via systematic, standard surveys to assess restoration success.

Factors Affecting the Presence and Abundance of Amphibians, Reptiles, and Small Mammals under Artificial Cover in Southern California

Artificial cover objects (ACOs) are known to attract small terrestrial vertebrates, but the actual parameters that attract species to ACOs can vary across geographic regions and climates. For this study ACOs were placed in coastal sage scrub and grassland habitats in southern California and surveyed weekly for small terrestrial vertebrates over a 4-yr period. We observed 1643 individuals of 34 taxa during 143 survey sessions totaling 16,312 ACO days. Overall species richness and abundances under ACOs were highest from February to April. Our results showed that the probability of encountering a reptile under an ACO was highest in February and March under large wooden ACOs containing moist soil, when temperatures under the ACO were relatively mild, and when minimum air temperatures were low. At the community level, encounter probabilities for small mammals were highest for large wooden ACOs and ACOs with low soil moisture, with several species differences. Amphibians of three species were only captured in low numbers primarily under wooden ACOs from November to March. Use of ACOs in research and monitoring is an inexpensive and simple way to document and capture a wide variety of small terrestrial vertebrates. Species richness and abundance can be maximized over short periods using ACOs and can be equally important for long-term monitoring, particularly once the factors that make ACO use effective for small terrestrial vertebrates of a certain region have been investigated.

Resilience of native amphibian communities following catastrophic drought: Evidence from a decade of regional-scale monitoring

The increasing frequency and severity of drought may exacerbate ongoing global amphibian declines. However, interactions between drought and coincident stressors, coupled with high interannual variability in amphibian abundances, can mask the extent and underlying mechanisms of drought impacts. We synthesized a decade (2009–2019) of regional-scale amphibian monitoring data (2273 surveys, 233 ponds, and seven species) from across California's Bay Area and used dynamic occupancy modeling to estimate trends and drivers of species occupancy. An extreme drought during the study period resulted in substantial habitat loss, with 51% of ponds drying in the worst year of drought, compared to <20% in pre-drought years. Nearly every species exhibited reduced breeding activity during the drought, with the occupancy of some species (American bullfrogs and California newts) declining by >25%. Invasive fishes and bullfrogs were also associated with reduced amphibian occupancy, and these taxa were locally extirpated from numerous sites during drought, without subsequent recovery– suggesting that drought may present an opportunity to remove invaders. Despite a historic, multi-year drought, native amphibians rebounded quickly to pre-drought occupancy levels, demonstrating evidence of resilience. Permanent waterbodies supported higher persistence of native species during drought years than did temporary waterbodies, and we therefore highlight the value of hydroperiod diversity in promoting amphibian stability.

Amphibians in a transition region between the Cerrado and the Atlantic Forest,west-central region of the State of São Paulo, Brazil

Studies of the diversity and natural history of amphibians are extremely important and contribute with the knowledge about the patterns of geographical distribution and biology of the species, outlining the factors that influence this distribution, and contributing to the development of conservation projects of them. This study aimed to identify the richness, abundance, spatial and temporal distribution of amphibians in the Bauru region, state of São Paulo, Brazil, and compare the species composition with others regions in the São Paulo state located in the Cerrado and Atlantic Forest. Eight locations were sampled between the years 2009 and 2012. Thirty-seven amphibian species were recorded, which represents 15.61% of the species in the state of São Paulo. In comparison to other regions of the state, Bauru resemble with the north-western region of the state and with the Assis Ecological Station in species composition. The community of amphibians in the studied region is regulated to morphoclimatic conditions, environmental heterogeneity and the conservation of natural resources, which directly reflect on the composition, abundance and species’ spatial and temporal distribution of the amphibians in this region. The richness of amphibians of the Bauru region is significant for the state of São Paulo and contributes with the maintenance of environments with conditions for the occurrence of Proceratophrys moratoi, which is considered in threat of extinction. This study contributed with the filling gap on the amphibian knowledge of the state of São Paulo.

Roads reduce amphibian abundance in ponds across a fragmented landscape

Roads threaten animal species through habitat loss, fragmentation and degradation, and direct mortality. It is crucial to understand how species respond to linear infrastructure for effective conservation of animal communities in fragmented landscapes. We assessed relationships between amphibian abundance and roads/ railways and habitat fragmentation. We examined whether the combined effects of habitat loss and roads or railways (accessible habitat) was a better predictor of amphibian abundance than (1) the total amount of habitat surrounding ponds, (2) distance to a highway or railway, or (3) surrounding road cover. Aquatic surveys for amphibian larvae were conducted at 30 freshwater ponds over the breeding season in a mixed peri-urban/ agricultural landscape in Hungary. Landscape variables were quantified within a 1000-m radius surrounding ponds and habitat variables were measured at the local (pond) scale. The larvae of seven amphibian species were detected. There were strong relationships between the abundance of amphibian larvae and the distance to a highway and the proportion of road cover within 1000 m of ponds. Relationships with accessible habitat and total habitat amount were uncertain, while there were no clear relationships with a major railway. Larval abundance increased with pond size, but there were mixed relationships with the presence of fish. Our results suggest that road effects were having a stronger impact on amphibian abundance than the combined effects of roads and habitat amount in the study area. Highways appeared to be negatively impacting amphibian communities within a wide road-effect zone up to 1 km from ponds. However, our results were obtained from a single-season snap-shot study and multi-season surveys are likely required to reduce uncertainty in the model predictions. Our analysis suggests that road mitigation projects for amphibians should create large ponds in areas with no highways and low road density, and with connectivity to surrounding habitats.

Habitat use and age structure of the Fer-de-Lance (Bothrops asper, Viperidae) in Braulio Carrillo National Park, Costa Rica

The Fer-de-lance or terciopelo (Bothrops asper) inhabits a wide range of environmental conditions and habitats across Central America. While much information on the species is based on anecdotal observations and useum specimens, data collected under natural conditions are more limited. To better document its natural history, this study sought to determine the habitat use and age structure of B. asper in the Quebrada Gonzalez sector of Braulio Carrillo National Park, Costa Rica. Snake surveys were conducted from January 2015 to August 2017 and used to evaluate the population age-class distribution and sex ratio. To evaluate macrohabitat use, surveys were conducted in four habitat types (mature forest, late succession, early succession, and human infrastructure). Microhabitat use was determined by recording several structural variables at each snake location and at random sites. Amphibians were sampled in each habitat type to evaluate the available prey base. Fifty-five individuals were captured, mostly females and juveniles, with five recaptures. Snakes were encountered in all habitat types but most often in early succession forests, which have dense vegetation cover and high prey availability. Snakes selected areas with heavy understory cover when resting, and more exposed sites, often closer to bodies of water, when ambushing prey or moving. Human-disturbed sites were used least. Although snake encounters did tend to correlate with higher amphibian abundance, other factors such as mammalian prey abundance could also influence snake distribution.

Diversity of Amphibians and Reptiles at Chiremera Locality, Vanduzi - Mozambique

Diversity of amphibians and reptiles was studied at Chiremera locality in Manica Province, Mozambique. To the best of our knowledge, no herpetofauna study has been done at the Chiremera locality. Globally the herpetofauna of Mozambique remains poorly documented compared to other areas of southern Africa [1]. The study aims to assess the diversity of amphibians and reptiles at Chiremera locality. The data was collected using two techniques: Visual Search and Intercept and pit fall traps. The data was collected in two habitat types: wild areas and human altered areas. We recorded on the wild areas 91 individual of amphibians (18 species, 10 genera and 9 families). The human altered areas had a total of 27 individual amphibians, (4 species, 4 genera and 4 families). Hemisus marmoratus (marbled snout-burrower) was the most abundant species in the two habitats, accounting for 26.3% of all individuals identified. The Shannon winner of amphibians was higher at the wild areas (H '= 2, 1) and lower in the human altered area (H' = 1, 2). A total of 24 individual reptiles were recorded on the wild areas (7 species, 7 genera and 5 families). In contrast to human altered areas we recorded (5 species, 3 Genera, and 3 families). Bitis arietans (puff adder) was the most abundant reptile accounting for 26% of all individuals identified. The Shannon wiener of reptiles was (H’=1, 6) at the wild areas and (H’=1, 5) at the human altered areas. Four rare species namely Hyperolius acuticeps (sharp-headed long reed frog), Hyperolius benguellensis (Benguella long reed frog), Ptychadena subpunctata (spotted ridged frog) all amphibians and Naja mossambica (Mozambique spitting cobra) - reptile were detected during our study. The result of the current study revealed that effect of human altered areas on the richness and abundance of amphibians and reptiles.

Foraging Behaviour of the Black-Headed Heron at Kibimba Rice Scheme, Eastern Uganda

Variations in the factors affecting prey availability directly impact on the spatial dispersion of foraging birds. The feeding success and efficiency of the Black-headed Heron (Ardea melanocephala) was examined in the different growth stages/phases of paddy rice, namely: Ploughed fields, Phase 1 fields (2 weeks-1 month after sowing) and Harvested fields. Feeding success of the Black-headed Heron varied significantly across the rice growth stage. This variation was explained by a combination of factors such water depth, waterbird abundance, Nearest Neighbor Distance (NND) and food or prey abundance (except amphibian abundance). Statistical analysis were conducted using Genstat Version 8.1 (VSN Intl.2003, in which a General Linear Mixed Model were used to examine the variation in each behavioural measure. Foraging in aggregations on rice paddies seems to be more beneficial to the Black-headed Heron. The closeness to a conspecific had a positive effect on the feeding efficiency of the Black-headed Heron as they foraged on fields with abundant prey (Phase 1) and a negative effect on fields with less abundant prey (Ploughed fields). Generally, the data seem to suggest that there is a functional relationship between the Black-headed Heron, and prey abundance, and the absence of interference competition on rice fields.

Seasonal monitoring of Hida salamander Hynobius kimurae using environmental DNA with a genus-specific primer set

The diversity and the abundance of amphibians have dramatically declined globally over the past 30 years, and the monitoring and conservation of their habitats is essential. However, traditional methods such as bait trapping and mark-recapture are costly, and morphological identification usually requires a high level of taxonomic expertise. Here, seasonal surveillances of Hida salamanderHynobius kimuraewere performed by means of environmental DNA (eDNA) analysis withHynobius-specific primers and a species-specific TaqMan probe. Water sampling and visual surveys were conducted seasonally in a stream in Kyoto Prefecture, Japan. Detection rates of eDNA were then calculated by real-time PCR, and eDNA site occupancy probability was estimated by multi-scale occupancy modeling. The eDNA-based detection rate of Hida salamander was 76.7%, whereas the visual survey-based detection rate was 23.3%, and target eDNA was detected at almost all sites where the presence of target species was visually confirmed. Moreover, factors relating to the site- and sample-level occurrence probabilities of the target eDNA differed depending on the developmental stage of the target species. Our findings support previous studies showing that eDNA analysis enables an effective assessment of amphibian distributions without damaging the organisms or their habitat, and we compare for the first time the site occupancy probability of amphibian eDNA throughout the life cycle of an amphibian species. The present study contributes to the development of eDNA analysis as a tool for understanding the distribution and seasonal activity of amphibian species and will thus aid in the planning of conservation measures and habitat restoration for these species.

Beavers in lakes: a review of their ecosystem impact

The aim of this review is to analyze the literature on the impact of beavers on lakes, summarize their effects, describe consequences for biotic and abiotic components, and highlight unresolved issues and perspectives. Beaver activity changes vegetation structure to the greatest extent, indirectly affecting other ecosystem components. Damming of flowing lakes increases the littoral area, which affects diversity and abundance of invertebrates, amphibians, birds, and mammals. Beavers’ alteration of the water regime and heterogeneity and connectivity of habitats has significant effects on zoobenthos, fish, and amphibians. Changes in hydrochemical properties directly affect phytoplankton and benthos. Unlike river ecosystems, where habitats are altered from flowing to still water, in lake ecosystems, habitat type is not usually changed (from lotic to lentic) but their quality (e.g., heterogeneity, connectivity) is. Beaver activity in rivers leads to increased limnophilic biodiversity, but in lakes, it leads to conservation of pre-existing lentic ecosystems. Therefore, impacts of beavers could be of greater importance to limnophilic complexes in lakes than to streams, especially after long time of beaver absence. Digging activity has a more significant role in lakes (especially floodplain) than in rivers. Beaver alteration of heterogeneity and connectivity of habitats is well studied, but not enough is known about impacts on the water regime of seasonally flowing waters, hydrochemical changes (especially eutrophication), amphibian life cycles, phytoplankton and zooplankton communities, parasitocenoses, and coarse woody debris. Methodological difficulties are noted, which are associated with the correct choice of control lakes. Further studies on riverine lakes are crucial. In considerations of climatic changes and anthropogenic impact, beavers may be an additional aid to conserving small lake ecosystems.

The hazard and unsureness of reducing habitat ranges in response to climate warming for 91 amphibian species in China

Quantifying the unsureness and recognize the hazard of habitats loss from changing climate conditions is important for adaptation of biodiversity to climate warming. The unsureness and hazard of losing habitat ranges for 91 amphibian species in China in response to climate warming were examined by applying climate scenarios of representative concentration pathways and categorization methods of the fuzzy set as well as the Monte Carlo techniques. For non-random scenarios of shifting climate conditions, the abundance of amphibians enhanced in certain sites in northeastern, western China, and declined in certain sites in southeastern, central, eastern, and northern China. For non-stochastic scenarios of changing climate factors, approximately 18–29 species narrowed not more than 20% or 20–40% of their present habitat ranges, and about 74–83 amphibian species occupied over 80% of their overall habitat ranges. Under stochastic scenarios of shifting climatic conditions, the count of species that dwindled different levels of the present or overall habitat ranges declined with improving the possibility; with the likeliness of over 0.6, the number of species that shrunk not more than 20%, 20–40%, 40–60%, 60–80%, and over 80% of the modern habitat areas was roughly 5-11, 4-8, 0-2, 1-3 and 16-24, respectively; the number of species that inhabited not more than 20%, 20–40%, 40–60%, 60–80%, and more than 80% of the overall habitat areas was more or less 1-2, 1-5, 1-6, 0-3 and 25-30, respectively. Approximately 37 amphibian species would be in danger of extinction in accordance with the shrinking habitat ranges due to altering climate conditions, and the measures would be necessary to assist these species to adapt to climate warming.

Impact of habitat alteration on amphibian diversity and species composition in a lowland tropical rainforest in Northeastern Leyte, Philippines

The impact of anthropogenic habitat alteration on amphibians was investigated, employing an investigative focus on leaf-litter and semi-aquatic species across different habitat alteration types. The habitat alteration types which include primary forest, selectively logged primary forest, secondary forest, abandoned farm areas and pasture (this represents a gradient of habitat alteration ranging from least altered to most altered, respectively) also encompass two habitat types: stream and terrestrial. Species assemblage was compared between habitat alteration types and habitat types, where a total 360 leaf-litter and semi-aquatic amphibians were observed (15 species, 6 families). It was found that amphibian abundance was significantly higher in both forest and stream habitat, and species richness did not differ with respect to habitat alteration type. It was determined, however, that species richness was highly dependent on habitat type (significantly higher in stream habitat). Meanwhile, diversity (Shannon–Wiener) was significantly higher in both forest and stream habitat, and species composition differed markedly between habitat alteration types for stream strip plots. Forest habitat exhibited domination by forest specialist species, while altered habitat (abandoned farm areas and pasture) exhibited domination by open-habitat specialist species. Additionally, strong relationships were found between species composition and abundance, as well as richness and diversity (within the measured habitat structures and observed microclimatic conditions). Analyses determined that the higher abundance of leaf-litter and semi-aquatic amphibians was best explained by higher DBH (1.3 m from the ground) and lower temperature and the higher species richness was best explained by higher understorey density. Additionally, higher diversity was associated with increasing understorey density, tree density and temperature. In general, the assemblage of leaf-litter and semi-aquatic amphibians in the lowland tropical rainforest in northeastern Leyte was affected by habitat alteration, highlighting the on-going importance of conservation efforts.

Salvaging bycatch data for conservation: Unexpected benefits of restored grasslands to amphibians in wetland buffer zones and ecological corridors

The degradation and loss of habitats are one of the major causes of the recent global decline of amphibian populations, and wetland ecosystems are increasingly restored to counter these effects. However, there is little information on how restoration of non-wetland habitats such as grasslands affect amphibians in wet-terrestrial habitat complexes. We studied the spatial and temporal impacts of large-scale grassland restoration in wetland buffer zones and ecological corridors on amphibians in Hortobágy National Park (E-Hungary). We used bycatch data on amphibians inadvertently collected over seven years by Barber pitfall trapping in a post-restoration monitoring of invertebrates in restored and natural grasslands. Repeated measures analyses revealed higher abundance and species richness of amphibians from year 2 to 6 after restoration than in years 7 to 10. Early phases of restoration, dominated by weedy and dicotyledonous plants, provided suitable microclimatic refuges and foraging areas to amphibians. The availability of such microhabitats decreased in later phases of restoration, dominated by grasses and a few dicotyledonous plants. Legacy effects were important because fine-scale differences in crop history and seed mixture resulted in variation in total abundance and species richness. Space-for-time substitution analyses two and seven years after restoration also confirmed the temporal differences between early and late phases of restoration. Restored grasslands did not differ from natural grasslands in total abundance, species abundances or species richness of amphibians. Our study demonstrates that increasing the area of grasslands around and among lowland marshes can be an effective tool for conservation because amphibians readily use these areas as refuges or for foraging, movement, migration and dispersal. Restoration of non-wetland habitat can benefit amphibians at the local scale by extending suitable terrestrial habitats and at the landscape scale by establishing functional connectivity between wetlands.

Relationships Between Chemical Defenses of Common Toad (Bufo bufo) Tadpoles and Bacterial Community Structure of their Natural Aquatic Habitat

Many organisms synthesize secondary metabolites against natural enemies. However, to which environmental factors the production of these metabolites is adjusted to is poorly investigated in animals, especially so in vertebrates. Bufadienolides are steroidal compounds that are present in a wide range of plants and animals and, if present in large quantities, can provide protection against natural enemies, such as pathogens. In a correlative study involving 16 natural populations we investigated how variation in bufadienolide content of larval common toads (Bufo bufo) is associated with the bacterial community structure of their aquatic environment. We also evaluated pond size, macrovegetation cover, and the abundance of predators, conspecifics and other larval amphibians. We measured toxin content of tadpoles using HPLC-MS and determined the number of bufadienolide compounds (NBC) and the total quantity of bufadienolides (TBQ). AICc-based model selection revealed strong relationships of NBC and TBQ with bacterial community structure of the aquatic habitat as well as with the presence of conspecific tadpoles. The observed relationships may have arisen due to adaptation to local bacterial communities, phenotypic plasticity, differential biotransformation of toxin compounds by different bacterial communities, or a combination of these processes. Bacterial groups that contribute to among-population variation in toxin content remain to be pinpointed, but our study suggesting that toxin production may be influenced by the bacterial community of the environment represents an important step towards understanding the ecological and evolutionary processes leading to microbiota-mediated variation in skin toxin profiles of aquatic vertebrates.