Limb bone morphology often correlates with functional demands placed on animals by the environment. Comparisons of limb bone allometry in functionally divergent turtle taxa indicate highly specialized lineages show extensive flattening of the humerus. In Sea Turtles this contributes to flipper-shaped forelimb morphology that facilitates lift-based swimming (i.e., underwater flight). In contrast robust humeri and femora in terrestrial tortoises may reflect specializations for resisting high torsional loads during terrestrial walking and digging. However, it is unknown whether allometric patterns of ecomorphological divergence can be detected among more closely related lineages within clades that encompass species with diverse ecological habits. To test whether limb bone size and shape vary among closely related taxa that live in divergent habitats, we used phylogenetic comparative methods to assess scaling patterns and overall morphology of the humerus and femur of 27 emydid turtle species representing four genera: Graptemys (semiaquatic), Pseudemys (semiaquatic), Trachemys (semiaquatic), and Terrapene (terrestrial). In general, we found that limb bones of emydid taxa scale isometrically for most length–diameter and length–mass relationships. However, terrestrial Terrapene (box turtles) species exhibit relatively short femora compared with species from the more aquatic genus Trachemys (sliders). The relatively small limb bones of box turtles may promote limb withdrawal into the shell, but without mechanical costs because of high safety factors of turtle limb bones. The comparatively robust forelimb and hindlimb dimensions of Graptemys (map turtles) relative to other emydid clades may reflect habitat and foraging pressures in this group.

Venomous snakes are a public health concern in India, where they kill tens of thousands of people annually. Russell's Vipers are the major culprit, but despite their clinical significance, there is virtually no information on their ecology. I used radiotelemetry for a 9-mo period to study the spatial and behavioral ecology of a population of Russell's Vipers (Daboia russelii) in a human-dominated rural landscape in Karnataka, India. Russell's Vipers spent a substantial amount of time in plantations, which make up a significant proportion of the landscape. Snakes were the least active in March, a dry month with the hottest monthly mean maximum temperatures recorded; and spatial activity comparatively increased in late fall-early winter and May, corresponding with the timing of mating activities and the end of the dry season, respectively. Russell's Vipers basked throughout the year, but basking behavior was more frequent in January and February, when the monthly mean minimum temperatures were the lowest. The probability of observing a snake basking increased with decreasing minimum temperatures. Similarly, the snakes were found in ambush foraging postures during daytime throughout the year, and the odds of observing diurnal foraging increased with increasing minimum temperatures and was affected by an interaction between maximum temperature and sex. Overall, the data indicate that this tropical viper actively thermoregulates and is to some extent diurnal. This study provides the first quantitative field-based natural history information on Russell's Vipers, one of the most medically important snakes in the world.

Few ecological studies have been conducted on Gulf Coast Waterdogs (Necturus beyeri), and published studies have focused on relatively small stream sections of 125 m to 1.75 km. In 2015, we sampled 25 sites along a 13.4-km stretch of Bayou Lacombe (Saint Tammany Parish, Louisiana, USA) to better understand factors that may influence the distribution of Gulf Coast Waterdogs within streams. We checked 250 unbaited traps once per week for 3 weeks, capturing 170 Gulf Coast Waterdogs at 18 of 25 sites. We used hierarchical models of abundance to estimate abundance at each site, as a function of site covariates including pH, turbidity, and distance from headwaters. The abundance of Gulf Coast Waterdogs within Bayou Lacombe was highest toward the center of the sampled stream segment, but we found no evidence that pH or turbidity affected abundance within our study area. Site-level abundance estimates of Gulf Coast Waterdogs ranged from 0 to 82, and we estimated there were 767 (95% Bayesian credible interval [CRI]: 266–983) Gulf Coast Waterdogs summed across all 25 sampling sites. We derived an estimate of 6,321 (95% CRI: 2,139–15,922) Gulf Coast Waterdogs for the entire 13.4-km stream section, which includes our 25 sites and the adjoining stream reaches between sites. Our results suggest that Gulf Coast Waterdogs may be uncommon or absent in the headwaters, possibly because of shallow water and swift currents with limited preferred habitats. Gulf Coast Waterdogs favor the middle stream reaches with adequate depth and abundant preferred microhabitats.

We studied the reproductive phenology of five endemic Eleutherodactylus species that coexist in a mountain rainforest in Cuba and estimated their sex ratios at immature and mature stages. We tested the hypothesis that in Neotropical humid sites, reproductive activity in sympatric species will vary in the time of occurrence so that there is no complete temporal overlap. We also investigated whether the length of the breeding season was associated to relative testes size as a proxy for male–male competition. We inferred reproductive phenology from seasonal variation in the number of sexually active individuals, their gonad developmental stage, and male vocal activity from January 2003 to March 2004. Our data do not support the hypothesis of temporal segregation in reproduction for this assemblage because we found a prolonged reproductive pattern in the five species, but there was decreased breeding intensity in the cooler months (November–February). This deduction is supported by a drop in the weight of the ovaries and the number of vitellogenic follicles, absence of mature females or reduction of their abundance, and disappearance of male vocal activity in the winter. We found differences in relative testes size among species, which were not related to differences in the length of the breeding season, but rather to interspecific differences in sex ratio.

To provide estimates of Blanding's Turtle (Emydoidae blandingii) hatchling survival and to better understand the utility of alternative management tactics targeting this age class, we monitored survival and movements after natural (caged) and artificial incubation by using radio telemetry. We found that survival was similarly high (ca. 80% over 88 days) across treatments and study locations. Movement distances were similar among treatments but differed among study locations, perhaps because of differences in release site habitat variables. Our results suggest that nest cages and artificial incubation are equally effective methods for increasing survival to hatching. Extrapolating from the 88 days of our study, until resumption of activity following hibernation, we found survival estimates of 40%–78%, depending on the survival function used. When coupled with published rates of nest survival (6%–41%) and hatch success (47%–87%), anticipated age 0 survival, from egg deposition to emergence from hibernation, ranged from 1%–28%. Although our analysis fills a knowledge gap in Blanding's Turtle demography, further study is needed to improve the precision of survival estimates.

Recreational activities can be detrimental to biodiversity; for example, off-road vehicle traffic (e.g., ATV riding), which has become increasingly popular in recent decades, can threaten wildlife. Although ATV riding around wetlands may threaten the shallow nests of turtles, there are no data on the effect of ATVs on turtle nests. We studied nest site choice and nest survival in two species of softshell turtles (Apalone mutica and A. spinifera) along a river in Louisiana before (1993–1994) and after (2015–2016) ATV riding became popular at the site to determine whether ATVs were an important source of nest mortality, and whether there was an effect of nest site choice on nest survival. ATVs were the most common source of nest mortality (one-third of nests destroyed); nest mortality was significantly positively related to increased ATV traffic but was not influenced by species or nest site choice. Experiments with surrogate eggs and an ATV revealed that the most vulnerable nests to ATV mortality were those that were shallower, were driven over more slowly, and were turned upon. We recommend restricting the access of riding clubs to the river; enforcement of regulations on isolated riders from adjacent residential areas will be logistically and financially challenging.

Adaptive coloration in amphibians is widespread and aids in camouflage, communication, and thermoregulation. Understanding the environmental factors that contribute to color variation is important for predicting how changes in climate and habitat parameters may alter amphibian fitness. Studies on toad coloration have focused on genetic elements, dorsal spot patterns, and juveniles, but less is known about the relationship between adult toad coloration and environmental conditions. The goal of this study was to examine dorsal color variation in adult American Toads (Anaxyrus americanus) in Erie County, Pennsylvania, USA, to determine how environmental and morphological factors influence coloration. We conducted visual surveys to sample adult toads across a habitat gradient and recorded several potential predictor variables (i.e., site elevation, substrate type, snout–vent length, and body surface temperature). We calibrated photographs of each toad and quantified red (R), green (G), and blue (B) color values within seven dorsal body regions. We summarized RGB values for each dorsal body region using a principal component analysis and used model selection approaches to select between models containing different predictor variables. The most supported model to explain the variation in color of all dorsal body regions contained only site elevation. On average, the body regions of all toads from higher elevation sites were darker than those of toads from lower elevations, but the amount of variation in dorsal coloration accounted for by elevation was low. Our results suggest that the factors that drive variation in toad dorsal coloration are complex, but that this trait is potentially sensitive to environmental changes.

The Roatán Spiny-tailed Iguana (Ctenosaura oedirhina) is an endangered species endemic to only two islands in the Bay of Honduras and a few of its surrounding cays. Ctenosaura oedirhina is currently threatened by different impacts, including habitat modification, invasive predators, and illegal collection and harvesting. Although previous work has monitored population numbers, animal distributions, and genetic variation, very little is known about the reproductive ecology and physiology of the species. Physiological indicators provide valuable information regarding the health of animals and populations. Commonly used metrics include circulating hormone concentrations, energetic indicators, and immunological indices. However, the aforementioned physiological measures can also be difficult to interpret because they are not static but rather vary according to sex, season, reproductive state, and body condition. Therefore, to understand the health status of an individual better, it is important to concomitantly measure multiple related and relevant physiological systems, and to examine these responses under different individual and environmental contexts (e.g., reproductive state, site). In the current study, we measured circulating plasma oxidative stress markers and energy metabolites in five populations of Roatán Spiny-tailed Iguanas during the prenesting season. We found significant physiological variation in females according to breeding state, and males according to population. Understanding the natural variation in the physiology of free-living animals will allow us to determine the significance of physiological measures such as health indicators in the future and thus better manage these threatened populations.

The jumping pitvipers of the genus Metlapilcoatlus are generally associated with montane environments and are widely distributed from central and southern Mexico to Panama. In this study, we analyzed the phylogenetic position and compared the morphology of a population from the Sierra Madre Oriental, within the Sierra Gorda Biosphere Reserve, to other species of jumping pitvipers. We implemented two mtDNA gene fragments (cyt b and ND4) of 50 specimens of the five Metlapilcoatlus species for phylogenetic reconstruction using Bayesian inference and maximum likelihood. We used a linear discriminant analysis and comparative statistics of external and hemipenial characters to assess the morphological differences among Metlapilcoatlus lineages. Our analyses support a strong genetic and morphological distinction of Metlapilcoatlus nummifer populations established to the north of the Trans-Mexican Volcanic Belt (Hidalgo, Northern Veracruz, and Querétaro) from other Metlapilcoatlus taxa. Based on this evidence we describe the populations from the north as a new species.

A recent taxonomic revision of geckos of the genus Hemidactylus Goldfuss, 1820 uncovered cryptic diversity within the Congolese population of H. nzingae Ceríaco, Agarwal, Marques and Bauer, 2020. Herein, we describe an unnamed southern Congolese lineage of H. nzingae as a new species. We base our description on previously published molecular evidence and newly collected morphological, meristic, and coloration data. Members of the group share a conservative morphology, and the newly described species is very similar to H. nzingae from which it differs mostly on the basis of coloration and tubercle scale rows. Our description is the first new species of gecko described from Democratic Republic of the Congo in nearly 7 decades and reinforces the already strong evidence that the country is a hotspot of reptile diversity.

Terrestrial migrations of salamanders are influenced by many factors, particularly temperature and moisture availability. Although photoperiod is generally an important migratory cue, it has not been specifically considered for salamanders. We examine the importance of the above abiotic factors at the macro- and microclimatic scales in the subterranean migration of a population of Cave Salamanders (Eurycea lucifuga) in Kentucky. This species exhibited a cyclic, seasonal migratory pattern between the twilight and dark zones in a cave. Our regression analysis of macroclimate indicated this migration was influenced largely by photoperiod, but also highly correlated with temperature and relative humidity; principle components analysis confirmed the importance of similar microclimate variables (illumination, temperature, and substrate wetness), explaining 88% of the variability in the data. These environmental variables fluctuate little in the dark zone of caves and thus likely do not provide cues on seasonal conditions to salamanders. However, these cues do vary in the twilight zone and may inform salamanders of epigean seasonal conditions. This information is critical to these cave-dwelling salamanders, particularly for finding suitable food resources.

The protection of rare amphibians depends upon accurate information about their distributions, yet cryptic, low-density populations are easily missed during field surveys. We used sites with known populations of the U.S. federally threatened species Rana chiricahuensis (n = 34) and its congener Rana yavapaiensis (n =11) in Arizona, USA to test whether a conspecific call stimulus can improve detectability of species. We show that the use of the evoked vocal responses technique improves the detectability of initially silent anuran populations of R. chiricahuensis and R. yavapaiensis by 45% and 71%, respectively. Evoked vocal responses, however, were not strictly species specific: 19% of R. chiricahuensis and 45% of R. yavapaiensis populations also increased their vocal activity in response to heterospecific stimuli. The low costs of the material (<50 USD per set) and the short time (1 min) to play a stimulus suggest that the additional costs associated with this technique will be minor relative to existing survey protocols. This technique offers the potential to improve the detection of other frog species, particularly in sites that are difficult to search visually, provided it is carried out by surveyors who can identify species by their calls.

Despite a 1944 publication questioning the misconception that Eastern Spadefoots (Scaphiopus holbrookii) and other Scaphiopodidae are ‘secretive’ outside of rain-induced migration and breeding aggregations, confirmation bias has perpetuated this fallacy. As a result, S. holbrookii is one of the least studied frogs in the United States. Amassing a large postmetamorphic dataset, we examined the misconception that S. holbrookii are secretive outside of breeding aggregates or optimal environmental conditions. Using eyeshine spotlighting, we conducted transect, mark–recapture, and haphazard spotlighting surveys in Virginia and Rhode Island forests. Although no breeding events or migration occurred during this study, we detected thousands of postmetamorphic S. holbrookii in Virginia and dozens in Rhode Island, the majority of which were subadults—a demographic category severely overlooked in the literature. These results are in direct contradiction with historical surveys of our sites. Spotlighting was an efficient method of detecting S. holbrookii eyeshine in forests, which were easily differentiated from arthropod eyeshine. Minimal effort was needed to detect the presence of S. holbrookii in Virginia and Rhode Island, even though both states have different climates and S. holbrookii densities. We also discovered a previously undetected population in Rhode Island. Scaphiopus holbrookii of all postmetamorphic size classes emerged regularly from burrows, even with no precipitation. We discuss how confirmation bias and lack of appropriate field methods for nonbreeding life history stages has fueled the misconception that S. holbrookii are difficult to find outside of optimal weather conditions, which has hindered progress studying the ecology and conservation of this species.

Amphibian responses to stress are generally mediated through glucocorticoids produced by the hypothalamic–pituitary–interrenal axis. Chronic elevation of glucocorticoids can result in delayed wound healing and growth, but less is known about its influence on behavioral responses to predators. We examined the effect of acute and chronic CORT elevation on exploratory and foraging behaviors of Allegheny Mountain Dusky Salamanders (Desmognathus ochrophaeus) exposed to kairomones from a predatory snake. We established ‘No CORT,' ‘Acute CORT,' and ‘Chronic CORT’ conditions during an 18-d preparation phase by varying salamander exposure to an exogenous source of CORT (0.51 mg/mL) delivered via cutaneous patch. During the trial phase, we conducted assays to evaluate exploratory and foraging behavior of salamanders from the different CORT groups when exposed to snake kairomones or control. Exploratory behavior was examined within a circular arena with a series of surmountable concentric barriers, and foraging behavior was observed within Petri dishes containing Drosophila prey. Salamanders experiencing both Chronic CORT and snake kairomones exhibited the least exploratory behavior, escaped the array with the lowest frequency, climbed the fewest barriers, and delayed their movement. However, foraging behavior (latency to strike at prey, number of strikes, number of prey captured) was not affected by exposure to CORT or snake kairomone. Our findings suggest that artificially elevated CORT can modify some behavioral responses to predator kairomones, but only when individuals experience multiple CORT applications in the period preceding the trials.