Introduced trout are a threat to native salamander populations. The ability of native salamanders to behaviorally respond to the presence of nonnative trout may be important in allowing their populations to persist in the presence of the nonnative predators. We experimentally examined whether adult and juvenile Ambystoma altamirani behaviorally respond to chemical cues from nonnative Rainbow Trout (Oncorhynchus mykiss) and a native garter snake (Thamnophis scaliger). Ambystoma altamirani did not respond to O. mykiss cues but increased activity in the response to T. scaliger cues. Ambystoma altamirani was less active when vegetation was present and this effect was greater in the presence of predator cues. There were no seasonal differences in activity. In conclusion, we demonstrated that A. altamirani responds to native snake predator cues but not to nonnative trout cues. It is unclear if naïve populations of A. altamirani from fishless streams will evolve antipredator responses to O. mykiss. Unfortunately, the inability of A. altamirani to coexist with O. mykiss in stream reaches where O. mykiss have already been introduced does not bode well for such a possibility.

Larval growth rate and metamorphic timing are often decoupled in biphasic, stream-breeding plethodontid salamanders; however, both of these life-history traits are plastic and variation among populations is driven partially by environmental factors such as water temperature. Urbanization often alters these environmental factors, possibly impacting the life history of the plethodontid populations remaining in these highly disturbed stream systems. We investigated the larval life history of Eurycea cirrigera (Southern Two-Lined Salamander) across an urban gradient in Atlanta, GA, USA, to disentangle the effects of urbanization, temperature, and stream size on larval period length and larval size. Across 14 urban streams, E. cirrigera larval period length was negatively correlated with summer stream temperatures; only streams with warmer summer stream temperatures lacked a 2-yr larval period. In addition, summer stream temperatures were positively correlated with larval size. Higher impervious surface cover (ISC) of the drainage basin was correlated with larger larval size, but mostly through the positive effect of ISC on stream temperature. These results expand our understanding of the mechanisms underlying variation in plethodontid life history and underscore the potential impacts of urbanization on amphibian populations.

The genus Salamandra encompasses six species with marked color pattern variations (yellow spots on black or primarily black or yellow) and reproductive strategies (viviparous and larviparous). This heterogeneity could be a consequence of habitat-specific adaptations, potentially related to the use of marginal ecological niches by some species or populations. This study investigated the habitat properties at 189 sites from the Iberian and Italian Peninsulas, northwest Africa, and the island of Corsica, where species of Salamandra are present: Salamandra algira, Salamandra atra, Salamandra corsica, Salamandra lanzai, and Salamandra salamandra. We used multivariate outlying mean index analysis to model species–environment relationships. The species showed differentiation in the habitat characteristics, and one group demonstrated specialization in high-elevation habitats (S. atra, S. lanzai). Our analyses also indicated that viviparous, primarily black phenotypes were associated with marginal habitats. By contrast, primarily yellow phenotypes were associated with habitats with structural properties similar to those used by typical (spotted-striped) phenotypes. These findings suggest complex regulatory mechanisms underlying the color variation in Mediterranean salamanders.

Population structure and survival are key components of wildlife management. Long-term monitoring of long-lived species, particularly those with indeterminate growth, is crucial when studying demographic processes. Here, we examined a population of Spur-thighed Tortoises, Testudo graeca, over a 7-yr period (17% of its life span), including changes in population structure, causes of mortality, and growth patterns. We found a change in population structure, as evidenced by lower young adult density (both males and females) and a more female-biased population compared to the start of the study. Juvenile mortality was high, and the main cause was predation by common ravens. For adults, mortality was relatively low and was mostly observed in winter or due to anthropogenic reasons (forestry or road mortality). We also modeled adult size-dependent survival and juvenile threshold survival (minimum number of juveniles needed to reach the adult stage to maintain population viability) using a Bayesian framework and matrix projection models, respectively. Adult survival was high (0.97), but with variation between the sexes. Female survival was not size dependent, but male survival decreased when size exceeded 150 mm carapace length. In this population, longer female life spans and climate change effects seemed to be the most likely reasons for our female-biased population. This study particularly pinpoints the importance of high survival in older females, which contributes to species credit, and stresses the negative potential of low juvenile and male densities in the population. Indeed, the annual juvenile threshold survival range was estimated between 0.32 and 0.49, not accounting for the predation exerted by common ravens in subadults. Therefore, if predation reduces juvenile survival rates below this threshold, population viability can be affected in the future. The study contributes to this species' conservation by anticipating time-lagged demographic responses based on current climate trends (less annual rainfall and more days over 40°C) and predation.

Aggressive behavior can be used to establish and maintain access to crucial resources such as space, food, and mating opportunities. Color polymorphic animals sometimes exhibit morph-correlated aggressive behaviors that can influence relative reproductive success and, thus, the maintenance of polymorphism. Aegean wall lizards, Podarcis erhardii, exhibit one of three monochromatic throat color morphs: orange, white, and yellow. Previously, male P. erhardii color morphs were shown to differ in their use of aggressive behaviors and ability to win staged contests during laboratory experiments. However, whether these color morphs use aggressive behavior differently in their natural setting where ecological and environmental factors are not standardized remains unknown. Here, we observed interactions of wall lizards over a large section of dry stone wall to investigate behavioral differences in aggression among color morphs in situ. We compared the counts and intensities (aggression scores) of aggressive behaviors (both performing and receiving aggression) and found that color morphs differ significantly in the frequencies and intensities of their aggressive behaviors. White morphs exhibited significantly more aggression than orange and yellow morphs on dry stone walls. Taken together, results from in situ and ex situ behavioral studies suggest that the smaller, more common white color morphs are more aggressive, which may help explain their relatively greater abundance and persistence across the species' range.

The distribution patterns of species can be impacted by biotic and abiotic factors that occur at both macro- and microscales. At a macroscale, species distributions can be impacted by spatiotemporal factors limiting dispersal and source–sink metapopulation dynamics that contribute to shaping geographic ranges. At a microscale, species distributions can be impacted by resources, microclimate, and interactions with other taxa. Thus, studying species at a single scale, or even at a single location, limits our understanding of the habitat needs and preferences. Herein, we study a lizard species, Sceloporus tristichus, that has a geographically diverse distribution, to understand the species' habitat needs and preferences at both macro- and microscales. We used species-occupancy models to identify habitat characteristics that are essential to predicting the presence of S. tristichus. In addition, we sampled various locations to understand the microhabitat preferences of the species. Last, we conducted a validation test to determine how well our model performed by choosing and sampling additional sites guided by the occupancy modeling results: two sites presumed to have the species and two presumed not to have the species. We found that the occupancy probability of S. tristichus lizards positively correlated with tree cover, tree height, and elevation. The detection probability of the species positively correlated with relative humidity. We also found that the species was using perches that were closer to the ground and cooler than what was available in that habitat. Our validation test verified our findings. Our results emphasize the need for old succession forests and particular tree species that are found at high elevations for S. tristichus occupancy. Herein, we have shown the importance of studying a species at different ecological scales to gain a holistic understanding of the species' ecological needs and preferences that can help in both comparisons with other congeners and conservation efforts.

Historically, predators have been classified into two categories based upon how they search for and acquire prey. Active or wide foragers move widely through the environment in search of prey, whereas ambush foragers sit and wait for prey to pass within attack range. The divergent energetic demands of these strategies have implications for movement behavior, with ambush foragers expected to exhibit reduced movement and space use relative to co-occurring wide foragers. We carried out an improved test of this energetics hypothesis by integrating radio telemetry, animal-borne accelerometry, and body temperature data logging in ambush-foraging Timber Rattlesnakes (Crotalus horridus) and wide-foraging Rat Snakes (Pantherophis alleghaniensis). Spatial movement estimates did not support our predictions, as there were no differences in movement distance or frequency estimates between C. horridus and P. alleghaniensis. Additionally, C. horridus used significantly larger home ranges than P. alleghaniensis. These unexpected results can be largely explained by limitations of standard spatial metrics, which did not account for vertical movements and space used by P. alleghaniensis during frequent arboreal bouts. Motion variance extracted from dynamic Brownian bridge motion models and accelerometry-derived measures of activity intensity (dynamic body acceleration) were critical for effectively quantifying movement patterns for both species. Motion variance indicated that C. horridus moved more variably than P. alleghaniensis, likely as a result of alternating bouts of sedentary ambush foraging and prolonged movements to new foraging locations. Accelerometry and temperature data logging revealed that P. alleghaniensis exhibited significantly higher activity than C. horridus and higher mean daily body temperature. The continuous recording of activity provided by accelerometers therefore revealed hidden variation in the movement behavior of the focal species that aligned with our predictions related to their differing foraging modes and energetic requirements. These results highlight accelerometer data logging as an important tool for improved field studies of snake movement ecology, especially in cases involving species for which radio telemetry alone might fail to capture important variation in the timing and intensity of movement.

Among the Crocodylia, maternal females of most species are known to attend their nests during the egg incubation period. However, the ecological and environmental factors driving nest attendance in these reptiles remain poorly understood. In 2019, we conducted a study in coastal South Carolina, USA, to examine temporal patterns of nest attendance by American Alligators (Alligator mississippiensis), investigate the site and environmental factors influencing nest attendance, and characterize behaviors exhibited by attending females. We used automated game cameras to monitor American Alligator nests throughout the incubation period and collected a suite of physical and environmental measurements at nest sites and associated habitat. Female attendance was modeled using generalized linear mixed-effects models with a binomial error distribution. Overall, nest attendance occurred for only a brief portion (1%) of the nesting period. The primary factors influencing nest attendance were day since oviposition, time of day, rainfall, and distance of nests to nearest water, with most attendance occurring during the first week postoviposition, at the end of incubation preceding hatchling emergence, at nighttime, shortly following rain events, and when nests were closer to water. Salinity of nearest water exhibited a weak effect, with the probability of nest attendance slightly decreasing as salinity increased. Maternal females exhibited four primary behaviors associated with nest attendance: crawling on the nest (16.2%), guarding the nest from a distance (62.2%), defending the nest (2.5%), and opening the nest and transporting young to water (19.0%), although temporal and behavioral patterns of nest attendance varied among individual females. At 8 (80%) of 10 nests predated by Raccoons (Procyon lotor), the maternal female returned and attempted to repair the nest. Nest defense by female American Alligators was low relative to the number of nest visits by egg and hatchling predators and other mammals. Collectively, our study reveals both environmental and nest site–level factors influence female nest attendance and, more broadly, demonstrates the importance of spatial and temporal scales of observation in studies of crocodilian maternal care.

Twenty-six species are currently assigned to the genus Pseudopaludicola. One of the most conspicuous lineages within this genus corresponds to the long-legged Pseudopaludicola saltica species group, where the three species, Pseudopaludicola jaredi, Pseudopaludicola murundu, and P. saltica, have tibiotarsal articulation extending beyond the tip of the snout. Here, we describe a fourth species belonging to the P. saltica group based on morphologic, molecular, and acoustic evidence. The new species can be distinguished from the other species assigned to the P. saltica group by a yellowish vocal sac in life (grayish vocal sac in P. jaredi and P. murundu and whitish vocal sac in P. saltica). The new species also emits a unique advertisement call compared to other species of the P. saltica group, resembling the rhythm of a galloping horse. This pattern, however, is remarkably similar to that of the distantly related Pseudopaludicola pocoto, suggesting independent evolution in these two species. The new species is described from a single locality in western Tocantins state, Marianópolis municipality (Brazil), in the Araguaia River floodplain. The new taxon described here is the sixth species of Pseudopaludicola known from the Tocantins.