Bergmann's rule states that endothermic species from cool areas tend to have larger body sizes than those from warm areas. Allen's rule maintains that endothermic species from cool environments should have shorter extremities than their counterparts from warm areas. Although a number of studies have supported both rules, the validity of these trends remains controversial, especially for ectothermic organisms. Here, we studied intraspecific morphological variation in Four-Eyed Frogs (Pleurodema thaul) to determine if these rules are valid in an ecogeographic context. Specifically, we analyzed how morphology varies across nine traits in males of P. thaul collected from nine localities in Chile. A discriminant analysis of all measured traits indicated differentiation between localities, and the first two canonical variables explained ∼80% of the total variation in morphometric features. Additionally, these two canonical variables were correlated with precipitation and monthly minimum temperature. To determine the validity of Allen's rule, a stepwise discriminant analysis was performed incorporating three morphological variables measured on the extremities of the individuals. This analysis indicated no variation in the traits between populations. The first canonical variable of the discriminant analysis explained 90% of the total variation in extremity morphology and was not correlated with environmental variables. We did, however, detect a correlation between the canonical variables of the stepwise discriminant analysis, and both minimum temperature and precipitation. Overall, our results indicate that the populations of P. thaul in Chile comply with Bergmann's rule.

Hotspots of amphibian species diversity typically occur in limited geographical ranges, and critically endangered habitats often contain a large number of endemic amphibian species. In such regions, it is prudent to engage conservation strategies for multiple amphibian species simultaneously. To correctly identify suitable habitats for multiple species, species interactions should be considered in species distribution models. In this study, we adopted a joint species distribution model to determine the abiotic and biotic factors that affect calling-site choice in three endangered co-occurring frog species on Amami-Oshima Island, and examined whether they co-occur more than expected after considering the overlapping preferences in environmental variables. Occurrences of Babina subaspera, Odorrana splendida, and O. amamiensis were assessed by monitoring mating calls using automatic digital voice recorders at 67 sites in 12 streams and explained by 8 environmental variables: water flow volume, temperature, pH, electrical conductivity, ammonium (NH₄ -N) concentration, elevation, slope, and forest stand age. The flow volume was negatively associated with occurrences in B. subaspera and O. splendida, but not O. amamiensis. Odorrana splendida occurred more frequently at higher elevations. Babina subaspera and O. splendida showed positive environmental correlations, indicating that they preferred similar environmental conditions, while exhibiting no negative relationships with each other. Our results indicated that B. subaspera and O. splendida do not avoid each other despite potential competition during the tadpole stage. Our results demonstrated that conserving preferable areas for O. splendida would also benefit B. subaspera with no negative species interactions, but not O. amamiensis. Considering species interactions in species distribution models will help us take more effective measures in the conservation of multiple species.

Frog diets are influenced by multiple factors, including morphological constraints, habitat use, and seasonal variation in environmental conditions and food availability. This study combined stomach content analysis (SCA), stable isotope analysis (SIA), and estimates of prey availability to investigate the influence of body size and microhabitat use on seasonal variation of the trophic ecology of two sympatric hylids (Pseudis minuta and Scinax squalirostris). We evaluated two hypotheses: (1) the species with larger body and mouth sizes or broader use of microhabitats will have greater diet breadth, and (2) regardless of differences in morphological traits and microhabitat use, diet breadth of both species will be greater during the warmer of two periods. Pseudis minuta exhibited larger body size and mouth width and revealed broader use of microhabitats (mostly within and near major water bodies), whereas S. squalirostris had smaller body size and mouth gape and was found exclusively within or near phytotelmata (plant-held water bodies). SCA revealed that P. minuta had a more diverse diet than S. squalirostris. Only P. minuta showed temporal dietary differences, but these findings did not corroborate our prediction of greater diet diversity during the warmer and drier period when prey densities were higher. The two species had distinct carbon and nitrogen stable isotope ratios, indicating assimilation of different resources, except during the colder wetter season when their isotope spaces overlapped partially. We concluded that the two hylids did not use the same food resources on account of their differences in morphology and microhabitat use, and environmental seasonality did not influence their feeding strategies.

Understanding patterns of resource use is an important aspect of the conservation and management of animal populations. We used stable isotopes of carbon and nitrogen from nail samples of Western Painted Turtles (Chrysemys picta bellii) to examine isotopic niches for individuals in an urban population. Western Painted Turtles are omnivorous, so we predicted that there would be little isotopic niche variation by sex, location, or age class. In contrast to our prediction, isotopic niche size varied up to three times among groups; females inhabiting marsh habitat had the largest niche, whereas females inhabiting creek habitat had the smallest. Isotopic niches overlapped 26–77%, with the least overlap between adult males and females, indicating niche partitioning by sex. Body size and location also contributed to the diversity of resource use. Isotopic mixing models indicated that all turtles consumed low proportions of a variety of prey items, but there were differences among groups. Turtles inhabiting creek habitat consumed higher proportions of chironomid larvae, whereas those in marsh habitat consumed higher proportions of crayfish and amphipods. Our findings indicate that urban turtles take advantage of a wide range of prey, and that aquatic systems with high productivity and diversity are well suited for maintaining turtle populations.

We report the results of a field study on Mexican Spotted Wood Turtles (Rhinoclemmys rubida perixantha) in a seasonally dry tropical forest of coastal Jalisco, Mexico. We used field surveys, trail spools, and radio telemetry to investigate activity patterns, estimate home range size with three different techniques, and develop a generalized linear model to identify features associated with habitats used by R. r. perixantha. We found that turtles were most frequently active at midday, with peak activity occurring from 0900 to 1500 h. During the dry season (January–mid-June), R. r. perixantha showed reduced activity (fewer movements and shorter travel distances) compared to the wet season (late June–September). Home range size did not differ among the three methods we compared, and all estimates revealed that R. r. perixantha have small home ranges, with males having larger home ranges than females. Sites used by turtles were positively associated with leaf litter and woody debris, herbaceous plants, vegetation, vine-like shrubs, and sloped terrain, and negatively associated with bare ground. Our findings can be used to strengthen future conservation efforts for R. r. perixantha, as well as other terrestrial geoemydids.

In many jurisdictions, rare species and their habitats can receive protection if species are assessed as being at risk of declining. The assessment process requires data on habitat occupancy as well as identification of threats to a species critical habitat, both of which are difficult to obtain when the species occurs across large spatial scales. Such is the case for Eastern Musk Turtles (Sternotherus odoratus), which are obligate coastal wetland species in the Laurentian Great Lakes. We use data collected between 2003 and 2015 to map occupancy and conditional occupancy for musk turtles in coastal wetlands of eastern Georgian Bay (Lake Huron) to identify threats to resident wetland habitat. Data collected from a synoptic survey of 58 coastal wetlands were used to create occupancy models, estimate detection probability, and to conduct a sensitivity analysis to determine model robustness. We had a 64–71% probability of detecting musk turtles, whenever present in the wetland, and an area under curve value of 0.82 confirmed high model accuracy. Coastal wetlands that supported musk turtles were associated with higher proportions of forest cover, lower densities of roads, buildings, and docks within 1 km of the wetland, and more-variable bathymetric slopes. High conditional occupancy across the majority of our study area indicates that, at present, habitat in eastern Georgian Bay is in good condition; however, land-use alterations and development should be limited to ensure the persistence of this population of musk turtles.

Little is known about the ecology and behavior of Rock Rattlesnakes (Crotalus lepidus) despite the species' wide geographic distribution throughout the southwestern United States and central Mexico. The goal of this study was to quantify space use, movement patterns, and habitat use by C. lepidus in the Chihuahuan Desert of extreme west Texas. We used radiotelemetry to monitor subjects during at least one activity season from 2007 to 2010. Mean (±1 SE) home range size for all individuals was 13.69 ± 3.06 ha, and mean daily movement rate was 8.46 ± 1.45 m/d. Although monthly movement rates were similar, movement was greatest in September, corresponding with the peak of the mating season for C. lepidus at our study site. We used multinomial logit models to analyze habitat use patterns among telemetered snakes while controlling for subject, estimated habitat availability, and season. Our subjects were most often observed using small arroyos, despite these habitats being relatively limited spatially within snake home ranges. Conversely, habitats typically associated with C. lepidus life-history (e.g., alluvial rocky slopes) were more available to our subjects, but were used less frequently overall. We also detected seasonal associations in habitat use, with subjects being more likely to use alluvial rocky slopes during spring and shifting to arroyo habitat throughout summer. Snakes also used microhabitats nonrandomly, most often seeking refuge under shrubs where ground cover consisted primarily of vegetation rather than rock or gravel. Our study presents a detailed analysis of habitat and microhabitat use by this species, and the patterns of movement and home range size reported here largely contrast to those found in the available literature on the spatial ecology of C. lepidus.

Natural rain forest enclaves in northeastern Brazil (called Brejos de Altitude) are present in isolated areas surrounded by the semiarid Caatinga biome. Among these montane areas, the Araripe Plateau in Ceará state harbors Caatinga, Cerrado, and Atlantic Forest remnants and is considered a priority area for biodiversity conservation. Herein, we describe a new species of Proceratophrys (Amphibia: Anura: Odontophrynidae; Horned Frogs) endemic to the Araripe Plateau. Based on nuclear and mitochondrial DNA sequences, we show that this new species is related to the Amazonian species P. concavitympanum but can be diagnosed based on the row of tubercles on the forearm and by the number, size, and disposition of tubercles on the dorsal region. It is also widely disjunct, known only from the mesic forests of the Araripe Plateau, 2400 km away from the type locality of P. concavitympanum. The new species depends on streams for reproduction and is currently known from an area that is severely impacted by deforestation and diversion of local streams for agriculture and recreation. Considering the many threatened species occurring in the same region, there is a need for future studies to quantify the new species' full distribution and evaluate population trends to correctly assess its conservation status.

A new species of Gerrhonotus, previously confused with G. infernalis, is described from the Cuatro Ciénegas Basin, Coahuila, Mexico. The new species is known from the type locality only and is characterized by the following combination of characters: a cantholoreal scale usually present, a dark mark extending anteriorly from the lower temporal scales through the lower border of the orbit to the preocular or cantholoreal scales, keeled dorsal scales, dorsal body pattern usually composed of cross-bands mostly interrupted or barely discernible on middorsum, usually indiscernible vertical dark bars on the lateral fold (few, faint bars occasionally present), and black flecks scattered on the venter. The new species is geographically closest to G. lugoi and G. infernalis but morphologically most similar to G. infernalis.