Effective species conservation and management plans are informed by spatial ecology. Specifically, a comprehensive understanding of a species' basic needs requires quantitative information pertaining to movement ecology at multiple spatial and temporal scales. In this study, we used radio telemetry to quantify home ranges and core use areas of the Flattened Musk Turtle (Sternotherus depressus; Testudines: Kinosternidae) and evaluate models explaining activity and movement patterns for the species in Alabama, USA. Home ranges averaged 332 m in stream length, whereas 95 and 50% kernel density estimators suggested core use averaged 185 and 86 m, respectively. Turtle activity increased late in the day and at night, as well as with precipitation. Movement distance increased with precipitation and water temperature, as well as during the breeding and nesting season compared with the post-nesting season. Home range size, core use stream lengths, activity patterns, and movement patterns did not differ significantly between males and females. Our study is the first to rigorously model activity and movement patterns of imperiled S. depressus, and we quantify home ranges and core areas of space use over multiple seasons, filling important gaps in our knowledge of this species.

Dam-created reservoirs are common landscape features that can provide habitat for amphibians, but their water level fluctuations and nonnative predators can differ markedly from more natural habitats. We compared fall movement and habitat use by the Oregon Spotted Frog (Rana pretiosa) in the reservoir pool with nearby river and pond habitats at Crane Prairie Reservoir in central Oregon, USA. Movement rate of frogs in the river and ponds declined as water temperature cooled. Reservoir frogs moved further than those in the river or ponds, and their movement rate increased as water temperature cooled. Most frog locations across all site types were in aquatic herbaceous vegetation. We did not find shifts in habitat between early and late fall. Increased movement and the lack of habitat shift in our reservoir frogs deeper into fall contrast with R. pretiosa in non-reservoir sites in this study and others. Consistent use of vegetation by reservoir frogs throughout the fall could indicate cover use in presence of fish predators. Our study provides additional detail on the range of habitats used by R. pretiosa in fall and suggests areas for further work to improve survival in constructed sites with abundant fish predators.

Functional redundancy occurs when different predator species have similar effects on the diversity, abundance, and composition of a prey community. When multiple predators coexist, their interactions can alter prey survival and ultimately diversity through emergent multiple-predator effects (MPEs). MPEs can be exacerbated by differences in predator behavior; however, little is known about the magnitude of MPEs when predators compete for the same prey or have similar behavioral traits. To understand functional redundancy and the interactions of multiple predators in similar niches, as well as their impacts on the composition of a prey community, we conducted two experiments using two ambystomatid salamander predators (Ambystoma opacum and Ambystoma annulatum). We exposed a suite of tadpole prey (Anaxyrus americanus, Rana sphenocephala, Rana sylvatica, Pseudacris feriarum, and Pseudacris crucifer) to different experimental food webs in a mesocosm experiment, and a single prey species (R. sphenocephala) in microcosm experiment with substitutive and additive designs to test for MPEs. We found no evidence for functional redundancy between the two predators: A. annulatum selectively preyed on competitively dominant prey species (A. americanus) and did not alter community diversity. Ambystoma opacum decreased prey diversity relative to the control because of natural phenological mismatch with A. americanus. Interactions between the two predators (e.g., predator inference) were lacking, indicating that predation risk from each predator was independent for the one prey species we tested. A better understanding of community and ecosystem-level effects by A. annulatum can inform future conservation efforts and management decisions regarding this endemic species.

Spatial distribution of animals is affected by environmental and social factors, acting both at inter- and intraspecific levels, and generating patterns of segregation or aggregation. Several studies investigated age-class segregation of the European Cave Salamander Speleomantes strinatii, in underground environments, showing a clear spatial segregation. We investigated the spatial distribution of S. strinatii on the forest floor, on 111 plots surveyed three times/season for two consecutive seasons, in northern Italy during autumn 2017 and spring 2018. We analyzed count data to model co-abundance of adults and juveniles, using a conditional two-species N-mixture model, incorporating environmental covariates. In contrast with what was observed in underground environments, we recorded no spatial segregation between juvenile and adult of S. strinatii on the forest floor. Instead, we found that adults and juveniles showed different responses to environmental features.

Compensatory recruitment can facilitate the persistence of populations experiencing high adult mortality. Because early life-stages of many taxa, including amphibians, are difficult to mark and recapture, sources of variation in survival at these stages often are unknown, which creates barriers to improving in situ recruitment rates. We leveraged count data and open N-mixture models to examine the environmental factors associated with the hatching of egg clutches, tadpole survival, and probability of metamorphosis in Boreal Toads (Anaxyrus boreas boreas) that inhabit pastures leased for cattle grazing in western Wyoming, USA. We conducted weekly surveys and measured a suite of environmental variables at 20 breeding ponds during May–September 2018. The hatching of egg clutches was most strongly related to pond surface area, as clutches often desiccated at smaller ponds. Weekly tadpole survival was lowest in ponds with high abundance of aquatic predators. Predation did not preclude metamorphosis, which was more strongly associated with higher dissolved oxygen and vegetation cover. Cattle grazing reduced vegetation cover in and around breeding ponds, which resulted in lower levels of dissolved oxygen. Grazing-induced habitat changes are therefore likely to negatively influence tadpole metamorphosis both via indirect effects on dissolved oxygen, and direct effects on vegetation cover, which also serves as feeding sites and escape cover from predators. We demonstrate the success of three critical phases in early life-stage development (egg hatching, tadpole survival, metamorphosis) was associated with different environmental factors. The inclusion of stage-specific responses in demographic analyses is therefore critical for a thorough understanding of what limits populations.

Reptiles and amphibians are surprisingly understudied in ecology. In this research perspective, I examine five areas of research in ecology, associated with the research areas and organisms that have attracted my interest as an ecologist for over 40 years. After discussing the forces and studies that shaped my interests and approaches I used as an ecologist, I then examine these fields, focusing on the utility of herptiles as study systems in each case. I first describe the use of reptiles and amphibians, but especially reptiles, as study organisms with which to examine the mechanisms of effects of anthropogenic habitat modifications. I then move on to describe the use of lizards in life history and performance evolution studies, including their use in studies of skin functional morphology and adhesion. After these descriptions, I briefly discuss the use of frogs in understanding disease ecology and cane toads as a system in which to study the control of invasive organisms. Finally, I discuss the use of long-term acoustic recordings of frog choruses to reveal ecological patterns. I put these areas into the framework of my own scientific trajectory from Canada to Australia and from life history studies on single species to preparing for pattern seeking in years-long, continent-wide acoustic recordings. All along, amphibians and reptiles have been outstanding model systems with which to make headway on a wide variety of ecological questions.

The endangered, endemic salamander, Ambystoma altamirani, is distributed in streams in the Transvolcanic Belt around Mexico City. Like other Mexican ambystomatids, A. altamirani is threatened by several anthropogenic stressors, including land use changes. Here we examine how aspects of the terrestrial habitat, such as the distance to wooded habitats and the presence of livestock, as well as several aspects of the aquatic habitat, affect the abundance of adult and larval A. altamirani along the Arroyo los Axolotes. The presence of livestock and proximity to the nearest trees did not affect the abundance of adult or larval A. altamirani. The abundance of adult A. altamirani was positively associated to the proportion of visits with water, mean total dissolved solids, mean stream width, mean bank height, and mean water velocity, and negatively related to mean water temperature and mean water depth. The abundance of larvae was not related to any measured variables. In conclusion, the abundance of A. altamirani along the Arroyo los Axolotes is primarily associated with aquatic factors, with limited influence of terrestrial factors. From a conservation and management perspective it is imperative to conserve the aquatic characteristics of streams where A. altamirani is found.

Anthropogenic salinization is a pervasive pollutant in much of the northeastern United States because of the widespread use of chemical deicing agents on roads. Although studies have examined the physiological effects of salinization on amphibians across life stages, behavioral responses to salinization of habitats are less studied. In this study, we experimentally test how salinity and temperature conditions experienced as larvae affect behavioral and physiological responses as juveniles. We first experimentally test whether juvenile Wood Frogs (Lithobates sylvaticus) can detect and avoid road salt in terrestrial soils and whether this avoidance behavior differs depending on temperature and salinity conditions in which individuals were raised as larvae. We also experimentally test whether temperature and salinity conditions experienced as larvae affect desiccation rates in juvenile Wood Frogs. We found a significant correlation between larval salinity conditions and choice of soil, with frogs raised in high salt aquatic conditions spending the majority of time on high salinity soils and frogs raised in low salt aquatic conditions spending the majority of time on low salinity soils. This behavioral response was muted in frogs raised in elevated temperature conditions. We were unable to detect a correlation between larval treatment and desiccation rate. Our experiments demonstrate that Wood Frogs can detect and respond to salinity levels in terrestrial habitats and that this juvenile response depends on environmental conditions experienced as larvae.

Cannibalism involves killing and consuming an individual of the same species. Different factors modulate cannibalism, and here we explored whether the diet diversity would mediate the cannibalism propensity in Microlophus lizards. We compiled the available information on diet and cannibalism of the 22 Microlophus species. We found that there is a relatively high incidence of cannibalism within Microlophus, as 41% of the species exhibited this behavior. There are, however, few reports of cannibalism by each species. Cannibalism propensity showed a positive association with diet diversity, which suggests that a generalist diet might provide room for cannibalism in Microlophus lizards. We also found that only adults, mostly males, consume juveniles. Conspecific predation pressure may explain the habitat segregation among age classes reported in some Microlophus species that exhibit cannibalism. Finally, cannibalism appears to be an ancestral condition in Microlophus, as it occurs in the two main clades of this genus. Moreover, Tropidurus, the sister taxon of Microlophus, also includes species that exhibit cannibalism, and the ancestor of these genera may have exhibited cannibalism.

As deforestation frontiers expand in the tropics, understanding species responses is critical to inform efficient land-use management policies. Here we evaluated lizard responses to changes in landscape, habitat patch, and quality in a deforestation frontier in southwestern Brazilian Amazonia. We first considered overall lizard assemblages and then two species subgroups of contrasting thermoregulation strategies. We sampled lizards at 21 forest patches (42–7,035 ha) subject to moderate habitat disturbance (e.g., cattle intrusion and selective logging). Based on 6,000 pitfall trap-days and 60,000 m of visual surveys, we recorded 215 individuals representing 15 species. Contrary to expectations, species richness and abundance were not explained by any of the variables considered, including matrix quality, proportion of forest cover, forest patch area and shape, age since isolation, arthropod biomass, canopy openness, litter volume, tree density, and fire history. However, the composition of persisting species was determined by the structural complexity of the adjacent matrix. The abundance of species that avoid direct sun exposure to regulate their body temperature increased under more-complex structures of adjacent matrix areas and decreased within patches more intensively affected by past fire events. Disturbance within forest patches likely decreased the patch-matrix contrast, contributing to the absence of forest area effects. Nevertheless, species-specific microhabitat requirements dictated part of the lizard species that were able to persist in the fragmented landscape. Strategies aiming to maximize lizard diversity should embrace retention of the habitat quality within forest patches and forest corridors/high-stature vegetation in at least some sites connecting forest remnants.

The southeastern United States supports some of the greatest levels of amphibian diversity in North America, and several species are in decline. Invasive species in the southeastern United States, such as the red imported fire ant (Solenopsis invicta; hereafter RIFA), may be a factor in amphibian declines via depredation, injury of, and/or competition with native amphibians for arthropod prey. Our objective was to assess the influence of RIFAs and RIFA reductions on the diet, growth, and survival of Southern Toads (Anaxyrus terrestris). In 2013 and 2014 we randomly assigned juvenile toads into enclosures either treated with an insecticide, hydramethylnon, to reduce RIFAs (hereafter RIFA treatment) or maintained with ambient levels of RIFAs (hereafter control; n = 4 enclosures per treatment). The mean proportion of recaptured toads was 9.5 and 21 times greater in the RIFA treatment compared to the control in 2013 and 2014, respectively. Toads in the control enclosures were 23% larger at the end of the study than toads recaptured in the RIFA treatment enclosures, though this was driven largely by differences in toad densities. Toad diets in the control and RIFA treatment enclosures overlapped 94%. When considering the dietary overlap of different ant genera only, the dietary overlap was 44%. Our study provides evidence RIFAs alter amphibian populations and may be contributing to amphibian declines in the southeastern United States. Given the high mortality rates we observed, RIFAs should be considered when developing conservation plans for any amphibian species found in areas where RIFAs are present.

Invasive species are widely believed to be a major threat to biodiversity. Therefore, invasive species control is a common practice among land managers. However, the impacts of invasive species control on nontarget organisms are often unknown. To examine the impact of invasive plant removal on a functionally important, but often overlooked, group of organisms, we carried out a field experiment focusing on terrestrial salamanders. Using coverboards, we monitored the occurrence of terrestrial salamanders (primarily Northern Ravine Salamanders, Plethodon electromorphus) in forest plots where invasive plants had been experimentally removed compared with control plots where removal did not occur. We replicated this design at three study sites and sampled coverboards over 3 yr (2016–2018; 2,187 sampling events). We also undertook a laboratory experiment exposing Northern Two-Lined Salamanders (Eurycea bislineata) to native and invasive plant root extracts compared with a plain water control. Results from occupancy modeling and other analytical techniques indicated strongly reduced occupancy of P. electromorphus in plots where invasive plants were removed, compared with controls. This pattern varied among study sites but was strongest at the most heavily invaded sites. Results from the laboratory exposure study showed no significant differences in response to root extracts from native versus invasive plants. Together, these data suggest that some terrestrial salamanders may not be negatively impacted by invasive plants and that invasive plant removal, when not accompanied by native plant restoration, may have unanticipated negative effects on terrestrial salamander populations.

The adults of the frog Atelognathus patagonicus display phenotypic plasticity and two morphotypes, namely, “aquatic” and “littoral”, and the transition from one to the other is a reversible way of adapting to different environments. The aquatic form lives underwater associated with vegetation and rocks and has lateral skin folds and interdigital membranes. Otherwise, the littoral form lives up to a few kilometers away from the water and does not have bagginess and the interdigital membranes are reduced. Considering that morphology and function of the visual system and skin composition are characters highly associated with habitat conditions, we performed a histological comparison of the eye and skin of both aquatic and littoral morphotypes of A. patagonicus. The aquatic morphotype A. patagonicus does not have an evident character that improves vision underwater, suggesting that clues for subaquatic life could not be only visual. However, the eyelid of the littoral morph has more mucous glands than that of the aquatic morph, which is consistent with the mucus secretion of these glands and its association with terrestrial environments. Also, the skin littoral morph is more keratinized and thicker than the aquatic one, which helps to prevent desiccation. Finally, the lateral skin of the aquatic morph is highly vascularized, suggesting an increase in cutaneous respiration. This work is a starting point for understanding, in an integrative way, the different mechanisms and systems modifications in the water–land transition of A. patagonicus.

Boana bischoffi was originally described from the Brazilian state of Rio Grande do Sul and has Boana multilineata from São Paulo as a junior synonym. The history of its nomenclature reflects the varying interpretation of the dorsal color pattern of the two different populations. We reevaluate the problem of taxonomic recognition of Boana multilineata based on molecular, morphometric, and acoustic data. The molecular data revealed two major clades that are partially concordant with the morphological and acoustic differentiation. Morphometric analyses revealed elements of differentiation between populations in snout–vent length (SVL) and head shape, which were patterns not detected previously. Discrimination considering call features was substantial, even complete in a discriminant analysis. Despite these differences, we refrain from resurrecting the name B. multilineata due to the existence of putative introgression zones, the effect of SVL in call dominant frequency, and lack of taxonomically relevant differences. Boana bischoffi might represent a case of incipient speciation.

The genus Proceratophrys currently comprises 40 species, of which five are distributed within the Caatinga domain and associated phytophysiognomies along northeastern Brazil. During field surveys at high altitudinal sites in Boqueirão da Onça region, northern Bahia state, we collected individuals of Proceratophrys that could not be assigned to any species currently known to occur within the Caatinga, which we describe herein. The new species can be diagnosed from remaining congeners based on vocalization, adult and tadpole morphology, and is also supported by molecular data (mitochondrial 16S, cytochrome b, and nuclear rhodopsin). We recovered the new species nested in the clade composed of species distributed within the Caatinga domain and associated phytophysiognomies, exhibiting a minimum of 7% of genetic divergence for the 16S gene in comparison to all its congeners. The new species seems to be restricted to high altitude locations (above 800 m) at the Boqueirão da Onça region, which represents the largest remaining contiguous Caatinga remnant (∼986,000 ha) being classified as of extreme biological importance.

Lepidodactylus browni Pernetta and Black, 1983 was described from mangrove habitat a few kilometers east of Port Moresby, Papua New Guinea. It was distinguished from L. orientalis Brown and Parker, 1977, described from Port Moresby, by differences in central tendency in adult snout–vent length, numbers of precloacal/femoral pores in males, and relative width of toe discs. We re-examine morphological data for these species and provide a molecular analysis of new sequences of each species to which we add existing sequences from the literature. We find large amounts of overlap between these taxa in the proposed diagnostic morphological characters and no distinction in the two between one mitochondrial and one nuclear gene. We conclude that L. browni is a junior synonym of L. orientalis and that the sole difference in central tendency in relative toe-pad width may be because of adaptation to different structural habitats.