For taxa with dispersal limitations, such as freshwater turtles, an understanding of their habitat and spatial needs can elucidate their risk to expected environmental and climatic changes. Florida Box Turtles (Terrapene bauri), a species of greatest conservation need, occurs in a diverse range of subtropical habitats on the Florida peninsula, including low-lying coastal areas subject to threats from climate change and sea level rise. We used radiotelemetry to assess the home range size and habitat use of Florida Box Turtles on a 37-ha anthropogenic, shell work island in southwestern Florida at the margin of its climatic niche. Home range calculated as 100% minimum convex polygons ranged from 0.29–1.52 ha with an average of 0.81 ha, which is consistent with, but smaller than, other parts of their range, and annual survivorship was estimated to be 0.875 (95% confidence interval = 0.67–1). Florida Box Turtles were most commonly located in tropical hardwood hammock forests (50.9%); other habitat use included shrub-scrub-cactus (29.6%), mangrove forest (13.4%) and shell barren (6.0%). Additional information on reproductive output, growth, temporal variation in survival, and response to disturbance such as hurricanes, storm overwash, and sea level rise is necessary to assess the long-term persistence of this population in the face of anticipated transitions of Florida's habitats because of global climate change.

In recent years, substantial variation in foraging behavior has been documented in lizards, including within and between closely related species. However, the exceptionally variable Gekkota still suffers from low sampling effort and historical averaging of foraging mode values across taxonomic levels. Herein, we address the gap in foraging modes of geckos by parsing out environmental and morphological sources of variation in foraging mode within the diurnal arboreal gecko, Phelsuma laticauda. Foraging behavior was examined at two sites on the island of Mo'orea, French Polynesia. In fall 2018, we made observations for a maximum duration of 30 min on 31 individual geckos. We found that P. laticauda exhibits a sit-and-wait strategy and that its foraging behavior is influenced by several ecological and morphological correlates: sex, body size, temperature, and date of observation. Notably, we found a trend for more active foraging by females than by males, challenging the notion that only nocturnal geckos exhibit sexual foraging diergism. The amount of time spent pausing and the maximum single movement exhibited a negative relationship with the body size of an individual. At higher temperatures, the amount of head movements, likely pertaining to locating prey, increased. Several foraging metrics varied with date of observation. Our results emphasize the need to consider multiple ecological correlates when studying foraging behavior as well as the importance of measuring multiple behavioral metrics beyond the standard percent time moving and moves per minute.

The Sahara Desert is the largest ecoregion in Africa, but its biodiversity in general, and reptile biodiversity in particular, are only superficially known and probably grossly underestimated. The dwarf-lizard genus Tropiocolotes is widely distributed in the region. The genus' taxonomy is plagued by serious nomenclatural problems that have led to a series of misidentifications of specimens in collections and in the literature. Analyzing variation in meristic and osteological characters of the Saharan species of Tropiocolotes, we found individuals from Algeria with unique external and internal morphological characters that distinguish them from all other species in the genus. We present a detailed account of these characters and describe two new species of Tropiocolotes from Algeria. Additionally, we provide the first detailed description of skulls of the genus, and designate a neotype to T. steudneri.

The Neotropical tribe Sphaenorhynchini includes 15 recognized species, 14 of which are allocated to the genus Sphaenorhynchus and 1 in the genus Gabohyla. Here, we redescribe the external larval morphology and include novel information on the lateral line system of G. pauloalvini and S. prasinus from the type localities. In addition, we include comments on the oviposition site and larval development of G. pauloalvini. The tadpoles of G. pauloalvini differentiate from all described larvae of Sphaenorhynchus by having a unique combination of stripes in the coloration: three lateral dark stripes (canthal, oblique, and ventrolateral) on the body and a single ventral dark stripe on the tail. The tadpoles of S. prasinus distinguish from those of G. pauloalvini and from all other larvae of Sphaenorhynchus by having a single, median, dark stripe on the tail musculature, among other characters. Tadpoles of G. pauloalvini and S. prasinus are nektonic and found swimming in the middle of the water column or in deeper regions of ponds. Adults of G. pauloalvini were observed sitting next to spawns, reinforcing the possibility of parental care in this species.

Caudal autotomy (the voluntary loss of a tail) is an important antipredator defense in many lizard species. The subsequent regrowth of the tail, seen in most lizards with the ability to autotomize, may pose some physiological costs both during the regrowth process and during potential repeated autotomy. In this study, we examined the physiology and behavior of the lacertid lizard Podarcis siculus, as well as the physiology and activity of the detached tails, following autotomy. Evaporative water loss and respiratory exchange ratio increased after autotomy, showing both an increased loss and a redistribution of important resources inside the animal. The lizards exhibited no change in behavioral thermoregulation during regrowth, as thermal preference did not change. Males and females differed in tail energy content, suggesting differing energy storage needs between the sexes. The rate of regeneration and tail movement between the sexes were not different, but tail movement did vary between previously regenerated tails and original tails, indicating a possible detriment to future autotomy events. Overall, autotomy appears to influence more than just a lizard's ability to escape, as our study provides evidence of potential physiological tradeoffs associated with this antipredator behavior.

The equal fitness paradigm (EFP) is a life-history model in which the currency of fitness is usable energy rather than individuals, and the principal trade-off is between survival, evaluated as generation time, and productivity, evaluated as growth and reproductive rates. In the current study I examined variation in generation time, age at first reproduction, productivity, and mortality in salamanders of the genus Desmognathus within the framework of the EFP. Desmognathus salamanders are restricted to eastern North America, with a center of distribution in the southern Appalachian Mountains. The data sources of the present report are published studies of life histories and demographics of five species of Desmognathus that include the smallest and largest members of the genus. The analysis showed that Desmognathus salamanders have greater ages at first reproduction, lengthier generation times, lower productivities, and lower mortality rates than are predicted by the scaling functions of the EFP for vertebrates of equivalent sizes. The differences among species in these parameters are correlated with variation in adult body size and the association between body size and habitat utilization in the genus, wherein the largest species are aquatic in mountain streams and the smallest are terrestrial in mesic forests. Streamside species of intermediate size exploit a broader range of habitats and are more widely distributed than the stream- and forest-dwelling forms. It is likely that the streamside mode of life in Desmognathus represents an adaptation promoting dispersal. Adaptive radiation in the genus is expressed in extreme life-history and body-size diversification mediated through variation in age at first reproduction and generation time.

Snakes have a wide range of antipredator behaviors that are often associated with unique morphological modification. Rhabdophis subminiatus (Red-Neck Keelback) is a snake with nuchal glands where toxins sequestered from prey animals are stored that work in conjunction with a set of antipredator behaviors. In this study, we investigated antipredator behavior in this species, particularly behavior that is coordinated with the presence of the nuchal glands. We tested the hypothesis that the nuchal gland-related behavior is exhibited more frequently as snake size increases because larger snakes have had more opportunities to consume toads and acquire toxins. We also examined the effects of sex and body condition on antipredator behavior. All snakes performed body flattening and neck flattening in response to a standardized stimulus, which suggests that these responses are their major antipredator behaviors. However, the results did not support our hypothesis. Snake body size was negatively correlated with the frequency of neck butt, neck flatten, and neck arch. This indicates that the tendency to perform the nuchal gland-related behavior declines as body size increases. There was no significant sexual difference except that females tended to exhibit a higher frequency of flight than males. Furthermore, we found a negative correlation between the frequency of neck butt and body condition. Overall, our study suggests that smaller snakes, particularly those in below-average body condition, depend more on nuchal glands to deter predators.

Sulawesi Forest Turtles (Leucocephalon yuwonoi) are critically endangered and endemic to the island of Sulawesi. We conducted radiotelemetry and capture–mark–recapture to study their spatial ecology, habitat selection, activity patterns, and demography in February–April and June–July, 2019. The average area occupied by 14 turtles using the minimum convex polygon (MCP) method was 0.49 ± 0.42 ha (standard deviation [SD]), whereas using the fixed 50% kernel density method averaged 0.076 ± 0.061 ha (SD). Males (mean = 0.53 ± 0.40 ha, N = 7) occupied a larger area (MCP method) than females (mean = 0.44 ± 0.46 ha, N = 7) but the difference was not statistically significant. Turtles took refuge in habitat containing significantly more canopy cover, broadleaf plant cover, and more and deeper ground cover than that in random plots. Males were predominantly active at night and females were exclusively so. We caught 25 adult females, 16 adult males, and 38 unsexed juveniles in two stream sections. Estimated population size (95% confidence intervals) in the lower stream was 17 turtles (15–28) in the wet season and 10 turtles (8–21) in the dry season. The population estimate in the upper stream was 25 (24–33) and 13 (9–28) turtles in the wet and dry seasons, respectively. Our study provides important baseline ecological data that can be used to inform future conservation and recovery programs for the species.

Excess nutrient runoff can profoundly alter aquatic habitats and has been associated with changes in host–pathogen interactions. Floating macrophyte mats have been suggested as a management strategy to improve water quality for aquatic communities and, thus, may have the potential to protect hosts from some disease outbreaks. We assessed the impact of ammonium nitrate and sodium phosphate addition in the presence or absence of floating macrophyte mats (blue flag iris [Iris versicolor] and ice dance sedge [Carex morrowii]) on Cope's Gray Treefrog (Hyla chrysoscelis) metamorphosis to examine whether macrophyte management treatments improve outcomes for amphibians. At metamorphosis, we infected individuals with the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), to assess whether larval treatments resulted in differential susceptibility to this pathogen. We found that nutrient addition significantly increased time to metamorphosis without affecting mass at metamorphosis or survival. Additionally, Bd exposure decreased mass of juvenile treefrogs, regardless of earlier larval environment or condition at metamorphosis. Macrophyte addition had no direct impact on larval anurans, but the aquatic community was altered via fluctuations in aquatic nutrient concentrations. Overall, our study suggests that nutrient exposure and Bd infection individually affect anurans, and larval exposure to nutrients may have latent effects on metamorphosed anurans that could affect future fitness.

Endocrine systems and individual behavioral differences (temperament) are often linked in animals. In particular, glucocorticoids (corticosterone [CORT]) have been implicated in animal coping styles, or syndromes of integrated temperamental and neuroendocrine variation. Typically, organisms with lower stress-induced elevations of CORT tend to exhibit more proactive behavior. Melanin-based coloration has been further linked to CORT physiology and temperament, with more melanistic individuals typically exhibiting more proactive coping styles. The melanocortin hypothesis proposes that variation in the melanocortin system could drive the repeated covariation in coloration, coping style, and CORT levels. We evaluated the relationships among the CORT stress response, boldness (i.e., responsiveness to risk), and melanization of the shell in Eastern Box Turtles (Terrapene carolina carolina), predicting that turtles with bolder temperaments would exhibit lower stress-induced CORT levels and possess darker shells. We also expected stress-induced CORT levels to be lower at cooler body temperatures. Our results generally failed to support the melanocortin hypothesis. We found no significant correlations among behavior, CORT, and melanization, and correlations that approached significance were weak. Moreover, the near significant relationship between CORT levels and boldness is in the opposite direction predicted. We also found that temperature had a strong positive effect on CORT levels, and there were population differences in plastron melanization and boldness.

The behaviors and activity season of Deirochelys reticularia miaria (Western Chicken Turtle) are poorly understood in Texas. Though distribution of D. r. miaria in the eastern portion of the state is widespread, turtle assemblage studies conducted within the range of the species in Texas have seldom documented its presence. There is a lack of formal protection for this subspecies and their habitat, and past research suggests that remaining habitat within the state is under threat from increasing urbanization. Therefore, the US Fish and Wildlife Service issued a 90-day finding that states listing the subspecies as threatened or endangered may be warranted. To provide survey recommendations for the western subspecies, we review species-wide capture techniques from the literature, recommend a survey season for D. r. miaria in Texas, and evaluate the efficacy and potential demographic biases of capture protocols implemented during field studies in the state in 2018 and 2019. We compared road surveys, dipnet surveys, seine surveys, night wading surveys, and two types of unbaited fyke net trap. Fyke nets were effective in every study that deployed them and captured D. r. miaria in this study at a rate of 0.25 captures per trap night. Dipnet surveys had the highest capture rate among active survey methods, but body size biases between methods were apparent. In Texas, road surveys yielded significantly lower capture rates than all other survey types. The best survey method selection will vary depending on research questions, budget, and time constraints. Utilizing proper survey protocols and understanding the activity season are crucial for performing effective studies on this species.

Eastern Diamondback Rattlesnakes (Crotalus adamanteus) are a species of conservation concern throughout their range. Yet, despite decades of population declines, C. adamanteus has not garnered protective status. With limited information on its general life history, more research is needed to manage C. adamanteus populations effectively, particularly at the southern extent of their distribution. To fill knowledge gaps in the ecology of C. adamanteus, we radiotracked six adult female and four male C. adamanteus from December 2015 to March 2018 (1,880 relocations) on a university campus in southwest Florida. Male snakes maintained large annual home ranges (mean = 65.7 ha 100% minimum complex polygons [MCP]) that were twice that of females (mean = 26.7 ha 100% MCP). Male snakes also made longer daily movements (mean = 39.4 ± confidence interval [CI] 34.7–44.0 m/d) than did females (mean = 16.7 ± CI 15.0–18.5 m/d), although both sexes showed variation among individuals. Snakes made considerable use of habitats adjacent to human development (<5 m from roadways and/or buildings), which consisted of more upland features than surrounding areas and may have provided thermoregulation benefits. However, snakes rarely crossed trafficked roads, which appeared to create barriers to their use of the landscape. Our research provides a better understanding of the spatial limits and dispersal patterns of C. adamanteus near the southernmost extent of its geographic range and within an urbanized landscape, which may assist in the implementation of effective management strategies.

Nile Crocodile (Crocodylus niloticus) populations that exist outside of protected areas are under threat in South Africa. They are believed to predominantly feed on fish, but they also take prey from the terrestrial system, which brings them into conflict with humans and hampers their management. Here, we use stable light isotope analysis to explore the diet of an unprotected Nile Crocodile population in the Olifants River, Mpumalanga and Limpopo Provinces. Nitrogen stable isotope ratios were obtained from fish and crocodile populations along the length (±430 km) of the river. The catchment is severely polluted with elevated d¹⁵N values at nutrient hotspots, which provides a basis for tracking the trophic response of crocodiles to the longitudinal profile of fish d¹⁵N values. Crocodiles did not respond to changes in the d¹⁵N values of fish populations and dietary predictions based on size-specific diet to tissue discrimination factors suggests a nonaquatic food base. These results suggest terrestrial diet dependence in one of the few viable Nile Crocodile populations from outside protected areas, posing unique challenges to their conservation.

Although hybridization processes in the Cheloniidae family have been documented since the 19th century, detailed reports of these occurrences are scarce. Therefore, the record of a hybridization between Green Sea Turtles (Chelonia mydas) and Hawksbill Sea Turtles (Eretmochelys imbricata) signifies an important event. In this study, we report the third known record of hybridization between C. mydas and E. imbricata in the Caribbean Sea. In Tortuguero, Costa Rica, we marked and monitored several nests from both species during the 2020 nesting season. Offspring from two E. imbricata clutches showed morphological characteristics corresponding to both species. We compared 20 individuals from each of these nests to large groups of pure C. mydas and E. imbricata individuals. We measured carapace length and mass of each hatchling and documented other morphological properties such as scale patterns on the head to better identify the species. Because these hatchlings presented different combinations of representative characteristics of each species, we concluded that they are hybrid individuals. Our findings provide a new record of a C. mydas · E. imbricata hybridization event.

Many aquatic organisms are experiencing increasingly severe and frequent droughts and drying events. Simultaneously, drought effects are carrying over to nondrought years as ecosystems remain in incomplete states of recovery. Aquatic organisms are thus faced with fewer sequential years under degraded environmental conditions to prepare for increasingly severe droughts and potential drying events. We assessed the effect of droughts and sex on the growth, mass, and mass-dependent estivation potential of long-lived aquatic salamanders (Greater Sirens, Siren lacertina) that estivate during drying events brought on by severe droughts. We calculated growth rates of S. lacertina based on mark–recapture data spanning 11 yr of a severe drought local minimum (of past 50 yr) in the southeastern United States. Sirens showed a distinct seasonal gain in body length and mass from March through September and little growth for the rest of the year. Gains during the growth season were strongly reduced by drought conditions. Although male and female sirens were predicted to reach a similar maximum body size, females grew much slower. Recruitment into drying event “size refugia” is constrained by drying event severity (determines minimum size required), frequency (determines available time between events to grow), and environmental conditions between drying events (determines the rate of growth). Thus, increases in drying event severity and frequency will require faster growth to a larger body size for successful recruitment into a size class that is resistant to drying events. The slower growth of females and reduction of growth during suboptimal years (mild to moderate droughts) suggest that the life history strategy of Greater Sirens for persisting through drying events potentially increases their demographic susceptibility to the predicted effects of climate change.