Anurans exhibit altered chorusing behaviors in response to anthropogenic noise, yet no studies have considered the effects of wind farm presence on anuran chorusing behaviors. We studied amphibian communities in a wind farm situated in a landscape that includes relatively pristine wetlands and forests. We measured amphibian diversity in habitats adjacent to wetlands using transect surveys, and we quantified anuran chorus and call characteristics (diversity, frequency, and duration) using nightly audio recordings in replicated turbine sites (<0.5 km from turbines) and control sites (>1.5 km from turbines). If wind farms present a source of disturbance, then we expected wetlands near turbines to have lower species diversity, lower chorus intensity, and altered call characteristics. We found significantly lower chorus diversity in turbine-site recordings, but no differences in biodiversity between turbine and control sites based on animals captured during transect surveys. Call characteristics did not differ between control and turbine sites; however, frogs calling in the wind farm displayed call characteristics similar to those of frogs calling near noisy roads within control sites, and some anuran species were notably absent from turbine sites. Identification of new threats, including those resulting from putatively green energy alternatives, is essential to mitigating global amphibian decline.

How organisms respond to abiotic conditions is paramount for predicting their response to climate change. Mechanistic models have been used extensively to predict the distribution and abundance of many organisms based on their physiology and behaviors. To provide further support for, and inform, mechanistic model predictions, relatively realistic laboratory experiments can be created to replicate natural climatic scenarios. We designed enclosures for terrestrial salamanders that allowed for manipulation of abiotic conditions in a relatively realistic way and for observation of both surface and subsurface behaviors. During a trial, enclosures provided realistic conditions that were an accurate reflection of the field conditions that our study species would be exposed to during their active season. Salamanders behaviorally responded to changing abiotic conditions in our enclosures in a similar fashion to what has been observed through long-term field studies. Our study also documented differences in subsurface behavior, with younger and smaller salamanders occupying shallower depths in response to days since feeding. Given the strong correlation between laboratory and field behaviors under current climatic scenarios, as well as the potentially unknown outcomes between abiotic and biotic conditions, we recommend using realistic laboratory enclosures to replicate future climatic conditions to further refine the predictive power of mechanistic models.

Intrasexual selection through male competition favoring larger male body size is the preferred explanation for the evolution and maintenance of male-biased sexual size dimorphism among polygynous species. Although sexual selection has been well studied in some groups of lizards, sexual selection in the nine species of lava lizards (Microlophus spp.) of the Galápagos has received little attention. The purpose of this research was to test the importance of male body size in the context of sexual selection by both sexes. Using three different sizes of robotic models capable of emulating the appearance and display patterns of male San Cristóbal Lava Lizards (M. bivittatus), we analyzed the responses that the models elicited among free-ranging lizards of the same sex (confrontation) and opposite sex (courtship). Results showed that body size of both male lizards and robotic antagonists influenced the number of displays performed by males. Male body size positively influenced the number of aggressive responses, scaling with the size of the opponent. The model representing larger lizards received higher display counts from males. Body size of robotic models, but not female lizards, influenced the number of displays performed by females. Females responded the most to the small and large models. Display intensity was not affected by any of the variables considered for either sex. Results from this study support the hypothesis that male-biased sexual size dimorphism in M. bivittatus is driven at least in part by both intrasexual and intersexual selection favoring larger male body size.

Contraction in the geographic range of Texas Horned Lizards (Phrynosoma cornutum) has long been suspected but not definitively examined. Contraction of a species' geographic range occurs through extirpation of local populations and thus might often be an early warning sign of further endangerment of the species. As such, there is a need to identify species distributional databases and develop statistical procedures for testing for range contraction. We developed a method based on regression and data randomization and then applied the method to museum (VertNet) and citizen-science (iNaturalist) data compiled for Texas Horned Lizards spanning the time period 1960–2019. The regression analysis examined whether distances between observations and the range center had decreased or increased over time. Decreases in distances could indirectly indicate range contraction, whereas increases could indicate range expansion. We conducted separate regressions for the four directional quadrants to assess the directionality of range change. Distance to VertNet observations in the eastern and western quadrants declined (P < 0.05) between 1960 and 2019, at rates of 4.4 and 1.5 km per year, respectively. The iNaturalist data (2000–2019) did not reveal significant declines in any of the quadrants. Further analyses indicated that these results were generally robust to the exact estimation (placement) of the historic range center. Our analysis provides the first quantitative assessment and test of contraction in the range of P. cornutum. Our method also demonstrates the utility of using museum and citizen-science data to monitor spatial distribution in other species that may be undergoing range contraction, although analyses must recognize inherent limitations of the data.

Despite its wide distribution throughout the northern Chihuahuan Desert, extraordinarily little is known about the ecology or behavior of Eastern Black-tailed Rattlesnakes (Crotalus ornatus). The primary literature for Black-tailed Rattlesnakes was largely based on research conducted on the former conspecific (C. molossus); thus, the revalidation of C. ornatus widened the void in our understanding of the species. The aim of this study was to elucidate movement patterns, home range size, and habitat use by C. ornatus in the northern Chihuahuan Desert of far West Texas. Radiotelemetry was used to monitor individual snakes for at least one active season (March–October) from May 2015 through August 2018. Mean (±1 SE) home range size for all individuals was 22.84 ± 4.49 ha and mean daily distance moved was 9.28 ± 0.93 m/d. Male snakes had larger home range sizes, larger core use areas, and greater daily distance moved than did female snakes. On a monthly basis, male movement peaked in August and female movement was statistically similar throughout the active season. Multinomial logit models were used to analyze habitat use patterns of C. ornatus, while controlling for snake, habitat availability, and season. Despite limited availability within snake home ranges, most observations of snakes occurred in arroyos or on rocky slopes. Microhabitat was also used nonrandomly, with snakes seeking cover in rocky refugia or under dense vegetation, rather than in areas containing high proportions of gravel or plant litter. This study presents the first detailed information about habitat and microhabitat use, along with patterns of movement and home range size for the recently revalidated C. ornatus.

Wild animal diets are challenging to quantify, and the various methods for doing so have strengths and weaknesses. Combining multiple methods can allow ecologists to assess their level of confidence in particular results, increase sample size, and investigate diet over varying time scales. The biases of traditional gut content–based methods are mostly well understood. Newer methods may have important biases that can only be worked out through comparison to established ones. We collected data on the diet of wild Plains Hog-nosed Snakes (Heterodon nasicus) using multiple, fundamentally dissimilar methods, combined analytically using a Bayesian framework to describe an ontogenetic dietary shift. Gut contents were the most straightforward, but yielded a small sample size that fell below any reasonable threshold for making generalizations. Stable isotopes indicated an obvious ontogenetic dietary shift, but were labor-intensive, and conclusions are limited by multiple methodological caveats including similarity among prey groups, maternal carryover effects, and uncertainty in trophic enrichment factors. Fecal environmental DNA (eDNA) was intermediate in terms of effort, yielding results congruent with the other two methods, but the interpretation of which would likely have been confounded by contaminants had we not used all three methods in tandem. Several apparent artifacts are discussed. There are some reassuring similarities among methods. There are also several differences. The most complete picture uses data from all methods taken together. Future studies should attempt to compare the biases, expense, and potential drawbacks of these and other methods in greater detail.

Habitat characteristics can have large effects on nest site selection of oviparous vertebrates. It is thought that habitat preference in many species is driven by natural selection because of habitat-specific fitness consequences. However, long-term studies on nesting of oviparous reptiles, in particular, are less common in comparison with other nesting vertebrates. As a result, specific habitat associations that define nesting habitat for many species are largely unknown. We studied habitat characteristics and selection of American Alligator (Alligator mississippiensis) nest sites in inland freshwater wetlands. We investigated the habitat characteristics associated with 112 nests studied during the 2013–2019 nesting seasons, and quantified habitat characteristics in relation to nest locations and random points. A nearest neighbor analysis indicated that American Alligator nests are not randomly distributed across wetlands, but are more representative of a clumped spatial distribution, suggestive of habitat preference and site selection. We measured habitat variables such as wetland vegetation cover, average water depth, island density, bank slope, canopy cover, and wet bulb globe temperature, as well as alligator population demographics such as relative adult proportion, at each nest and random site. Subsequently, we found that the best variables for predicting American Alligator nest site selection included island density, slope of bank, canopy cover, and wet bulb globe temperature. The best predictive model demonstrated that the odds of nest site selection increased with increasing canopy cover, wet bulb globe temperature, island density, and decreasing bank slope. These habitat choices presumably reduce the risk of nest predation and provide thermal cover for proper balance of nest site microclimate. Based on our results, practices focused on alligator nesting habitat should consider these specific habitat characteristics in outlining applied strategies and working toward management and conservation goals.

Invasion and spread of Red Imported Fire Ants (RIFA; Solenopsis invicta) is cited as a possible cause for enigmatic reptile declines in the southeastern United States. Reptiles are negatively affected by RIFA through predation of eggs, hatchlings, and adults. We used short-term (12-h) field trials early in incubation to evaluate whether RIFA could successfully depredate intact eggs from six species of native terrestrial oviparous snakes: North American Racer (Coluber constrictor), Speckled Kingsnake (Lampropeltis holbrooki), Prairie Kingsnake (L. calligaster), Rough Greensnake (Opheodrys aestivus), Black Ratsnake (Pantherophis obsoletus) and Great Plains Ratsnake (P. emoryi). Then we used an artificial nest field experiment at the end of incubation to test whether RIFA predation differed between a species that has apparently declined in areas of its range where RIFA has invaded (L. holbrooki) and a species that has apparently not declined (C. constrictor). We measured pip–hatch and incubation time for each species in the laboratory to determine whether differences in time between pipping and hatching (pip–hatch time) could account for interspecific differences in RIFA predation on eggs. Overall, RIFA predation rates on snake eggs were high for all species (25–67% during early trials, 50–100% at end of incubation), although P. obsoletus was only depredated after hatching in the field. Coluber constrictor had significantly shorter pip–hatch times than other species, but probability of predation by RIFA did not differ for C. constrictor and L. holbrooki. Our study provides novel observations of RIFA predation and suggests that time spent in nest, eggshell characteristics, and nest microhabitat may be more important than pip–hatch time in mediating vulnerability of snake eggs to RIFA predation.