In the first range-wide population viability model for the northwestern and southwestern pond turtles (Actinemys marmorata and Actinemys pallida, respectively), a stage-based population projection matrix was assembled with 3 life stages: hatchling, juvenile, and adult. Vital rates were defined using biologically appropriate statistical distributions, with additional parametric uncertainty included for the adult survival parameter. A triple-loop stochastic simulation model was built around a population viability analysis to project pond turtle populations into the future. Initial abundance was calculated using available historical presence data and remotely sensed landscape condition metrics. A negative binomial regression was used to predict the relationship between abundance, habitat area, and human modification. Populations of pond turtles are dominated by adult individuals, so we applied a nonstable stage distribution to initial abundance values. Initial abundances of analysis units were variable across the species' ranges, but all populations declined precipitously in the population projections. By the end of the century, the mean range-wide probability of extinction was 44.3% for the northwestern species and 57.8% for the southwestern species. Consistent with other long-lived chelonian species, population growth rate was most sensitive to adult survival, indicating that where possible, conservation efforts focusing on increasing or maintaining adult survival would benefit the species. Elasticity analysis indicated a bet-hedging life history strategy where long-term reproductive output is maximized through longevity, small clutches, and frequent reproductive bouts in the face of highly variable juvenile survival. The population dynamics presented here indicate that efforts to bolster adult survival would be most beneficial in terms of long-term population viability, which can inform targeted research and management. The feasibility of such efforts is an important consideration in conservation management for these long-lived species.

The Scorpion Mud Turtle (Kinosternon scorpioides) has been recognized by most recent authors to be a single species (3 subspecies) ranging from Tamaulipas, Mexico, to northern Argentina. However, recent molecular analyses have demonstrated that it is not monophyletic, but rather paraphyletic relative to other Neotropical Kinosternon. Based on extensive genetic sampling across the range of this species, a recent paper elevated the 3 subspecies (albogulare, cruentatum, and scorpioides) to species status, confirmed the divergence of Pacific and Atlantic versant populations of K. cruentatum, and recommended that both be given species status. However, the type locality of K. cruentatum is imprecise, making the allocation of the name problematic. Our study sought to determine the provenance of the type using morphometric analysis of specimens from across the range. That analysis demonstrates unequivocally that the type of K. cruentatum was collected on the Atlantic versant, likely from an eastern population. Furthermore, the analysis also revealed that the type of K. mexicanum, previously synonymized with K. cruentatum, was collected from along the Pacific versant. Hence, the name K. cruentatum should be restricted to populations in Atlantic drainages, and the name K. mexicanum should be restricted to Pacific drainages. Our analysis also indicated divergence among the 3 allopatric Atlantic versant populations, but future genetic work will be needed to determine whether they merit taxonomic recognition.

Determining activity rhythms is crucial for understanding the life history, ecology, and evolution of an animal species. Due to various anthropogenic threats, wild populations of Reeves' turtle (Mauremys reevesii) are diminishing throughout its geographic range in East Asia. Despite the endangered conservation status of this species, little is known about its activity rhythm. Therefore, the focus of this study was to radio track 23 wild Reeves' turtles in the field to determine their daily and seasonal activity patterns. We identified the Reeves' turtle as both diurnal and nocturnal, rather than the traditional classification of diurnal, with an average daily activity peak between 1800 and 2000 hours. In spring, the frequency of diurnal activity was higher than that of nocturnal activity, and males were significantly more active than females. In summer, total activity frequency increased significantly and was predominantly nocturnal, with no significant difference in activity found between males and females. In autumn, nocturnal activity decreased and males were significantly more active than females overall. Reeves' turtles hibernated from the end of October to mid-April. Our results elucidate the daily and seasonal activity rhythms of Reeves' turtles, thus providing a reference for understanding the life history of the species and potentially improving future conservation planning.

Preliminary bycatch reports from Kep and Kampot, Cambodia, confirm the presence of green turtles (Chelonia mydas) and highlight bycatch as a result of illegal, unregulated, and unreported bottom trawling as the most pertinent, perennial threat. Recommendations for conservation action emphasize the importance of a community-based approach, engagement, and education alongside continued extensive research, improved enforcement of current fisheries legislation, potential modification of fishing gear, and the development of Cambodian-led conservation initiatives to promote authentic environmental custodianship.

Gopher tortoises (Gopherus polyphemus), the only land tortoises native to the southeastern United States, are found throughout their range in a variety of upland habitat types, with their use of upland pine-dominated habitats receiving most attention. Fewer studies have examined their use of coastal beach dune habitats, but some of the highest gopher tortoise burrow densities have been observed in this vulnerable, yet critical, habitat. Gopher tortoises construct extensive burrows for their own use, and these burrows have also been shown to support numerous other animals (i.e., commensal species) that may depend on them for critical needs (e.g., shelter, food). Motion-activated wildlife cameras allow for nonintrusive and continuous observation of burrow activity with minimal disturbance to the animals and habitat. Here we examined 10 gopher tortoise burrows over a 12-mo period using motion-activated wildlife cameras in beach dune habitat in an undeveloped section of coastline in northeast Florida. Gopher tortoises were most frequently observed during the spring and summer months (April–August), and most often during daylight hours. Gopher tortoise behaviors such as burrow maintenance, mating, foraging, and resting were all observed more during April through August, which is a slightly earlier start than these activities have been observed in inland populations. We observed a commensal community of 51 animal taxa using tortoise burrows and their aprons, 29 of which we were able to identify to species. The commensal community was generally similar to those in inland habitats, but we did observe some taxa that were previously undocumented at gopher tortoise burrows including 2 bird species and 8 insect taxa. These commensals displayed varied diel and seasonal activity patterns, with many taxa observed at burrows concurrently occupied by gopher tortoises. Considered together, our observations of gopher tortoise behavior and their commensal community in coastal beach dunes provide valuable insights into the importance of this understudied habitat and highlight distinct differences from inland ecosystems.

This study provides, for the first time, reference intervals of sex steroids and thyroxine concentrations from free-living green sea turtles (Chelonia mydas) inhabiting the coast of Quintana Roo, Mexico, determined in serum samples (n = 150) collected during 2013–2019 and characterized by endogenous (sex, size, and reproductive stages) and exogenous (foraging site) factors. A new demographic classification is proposed based on sea turtle size and habit preferences. Enzyme-linked immunosorbent assays were used to quantify serum estradiol, testosterone, and free thyroxine concentrations of green sea turtles captured in 7 foraging localities along the coast. The mean curved carapace length (CCL) of individuals (n = 150) was 66.60 ± 21.26 cm (range: 26.2–116.4 cm); immature turtles of undetermined sex were the most frequent age class (79.3%). The mean steroid values were 0.33 ± 0.416 ng ml^–1 (0.001–2.85 ng ml^–1) for estradiol, 1.41 ± 1.83 ng ml^–1 (0.015–9.21 ng ml^–1) for testosterone, and 2.62 ± 1.89 µg 100 ml^–1 (0.001–9.22 µg 100 ml^–1) for thyroxine. The sex ratio estimated for adults (n = 31) was 1:3 (M:F) in deep near-shore habitats in the northern region. A bimodal distribution in the frequency of sea turtles grouped by size classes (CCL) was found, based on which a new theoretical size class classification is proposed for the Mexican Caribbean population. The 2 size classes were resident green turtles (26.2–80 cm CCL) and transient individuals (66.5–116.4 cm CCL), which also differed significantly in testosterone concentration, residents 1.6 ± 1.9 ng/ml (0.01–9.2 ng/ml) and transients 1.0 ± 1.3 ng/ml (0.08–5.1 ng/ml) (Mann-Whitney U-test = 1970, p = 0.04). Resident green turtles found along the central region of the Quintana Roo coast presented higher concentrations of testosterone than transients from the northern region (Kruskal–Wallis H-test = 6.8, p = 0.03). With the exception of testosterone, differences in steroid hormone levels between life-history stages, reproductive state, or sex were not found. Sex steroid concentrations did not differ significantly from reports worldwide, and thyroxine levels suggest an optimal nutritional condition of the individuals. Data presented in this work could be used as the basis for future health monitoring programs and demographic studies required to conserve this sea turtle stock.

Knowledge about the distributions of species and the variables influencing their occurrence is important for their management and conservation, but factors affecting occurrence can vary across the range of a species. Northwestern pond turtles (Actinemys marmorata) are widespread generalist turtles, but are nonetheless of conservation concern throughout their range. To better understand the distribution of northwestern pond turtles and introduced American bullfrogs (Lithobates catesbeianus), we surveyed streams on private timberlands of the interior foothills of northern California using visual encounter surveys and collecting samples of environmental DNA. We found that northwestern pond turtle occurrence was negatively related to elevation in our sampling frame. Detection probabilities with environmental DNA were approximately twice those of visual encounter surveys, but both methods were effective for detecting turtles in streams. American bullfrogs were detected in a single sample at each of 2 sites (one by environmental DNA, one by visual encounter surveys). Management for northwestern pond turtles in forest streams within our sample area will likely have the largest effect at lower elevation sites where turtles are most likely to occur.

Understanding which factors make an individual susceptible to parasitism provides insight on how a parasite infects a host. Numerous factors such as habitat characteristics, body size, and sex have shown differential impacts on parasitism rates. Trends in parasitism rate often exist for similar taxonomic groups, so expanding research to new species helps test the robustness of such trends. A chelonian-specific ectoparasite, Cistudinomyia cistudinis (Diptera: Sarcophagidae), has been documented in case studies dating back a century. Almost all reports of infection by this flesh fly are of a single or few turtles, so there is a lack of information regarding the population dynamics of infection. This lack of information means little is known about which factors make a turtle more or less likely to be parasitized. In this work, we compared the occurrences of parasitism in ornate box turtle (Terrapene ornata) populations across multiple seasons from 2 different habitats in northeastern Kansas (North Topeka and Lawrence). At the population level, we found a significantly higher number of parasitized turtles in the Lawrence population. Within the Lawrence population, we found females were more likely to be parasitized. This study sets baseline infection rates for a long-lived vertebrate host that can help better understand the reasons for parasitism both among and within populations.

To explore patterns of emigration of gopher tortoises (Gopherus polyphemus), we examined movements at a study site in south-central Alabama that consisted of 2 distinct aggregations of burrows located on adjacent north and south sandhills separated by a mesic depression wash. We collected telemetry data from 41 individuals over a complete season of activity (2000–2001) and capture-mark-recapture data of those same individuals during 14 trapping sessions from 1992 to 2020. We observed a bimodal distribution of telemetry fixes, with 1 mode created by individuals with few fixes (n = 9) who also were recaptured infrequently, which we interpreted to represent emigrants. Thus, our data suggest that the proportion of a local population that emigrates each year is on the order of 20%. To characterize the degree to which resident tortoises (those recaptured ≥ 5 times over the 29-yr period) used space across the entire study site, we used 100% minimum convex polygons to examine the proportion of annual home ranges (based on telemetry data) and lifetime home ranges (based on capture-mark-recapture and telemetry data) that involved both sandhills. For annual home ranges, only a single individual (of 14 residents) occupied burrows on both hills over 1 yr. For lifetime home ranges, 9 individual residents used burrows on both hills. Lifetime home ranges were 6 times larger than annual home ranges, with longest distances between vertices of lifetime home ranges approaching distances ascribed to emigration in previous studies. A model generated from the lifetime recapture data indicated a tendency for greater apparent survival of adults compared with juveniles on the study site and for juveniles and adult females to be more likely to move from the south hill to the north hill than the opposite direction. When added to 5 additional sites for which telemetry data were gathered, we argue that emigration rate is strongly and negatively correlated with local tortoise density. We conclude that current individual-based population models correctly separate movements of animals within a local population (residents) from emigration of animals among local populations, such models require addition of density dependence when addressing emigration rate, and dispersal distances are longer than those based on studies of movements within a single season of activity.

The savannah side-necked turtle Podocnemis vogli is a species restricted to the savannas of the Orinoco basin in Colombia and Venezuela. Because of its apparent abundance, it is currently categorized as Least Concern (LC) by the IUCN Red List. However, throughout its distribution range, several populations have been extirpated or individuals in remaining populations are consumed and trafficked, and the species' habitat has been highly degraded. To start assessing the conservation status of the species, 5 populations along their distribution range in Colombia were analyzed using 19 microsatellite loci to perform a population genetics study. Ten of those markers were useful in revealing (1) high levels of genetic diversity, (2) a marked genetic structure of 5 populations, and (3) low and asymmetric gene flow among them. However, the analyses also revealed the loss of genetic diversity (low allelic richness) and recent bottlenecks in some populations. Those identified detrimental indicators are evidencing a population decline most likely related to anthropic activities. These 5 populations correspond to 5 independent management units. The results of this research allow us to propose management and conservation guidelines for these populations in the Orinoco ecoregion.

La tortuga sabanera Podocnemis vogli es una especie restringida a las sabanas de la cuenca del Orinoco en Colombia y Venezuela. Debido a su aparente abundancia, actualmente está categorizada como en Preocupación Menor (LC) por la Lista Roja de la UICN. Sin embargo, a lo largo de su rango de distribución, varias poblaciones han sido extirpadas o los individuos en poblaciones remanentes son consumidos y traficados, y el hábitat de la especie se ha degradado intensamente. Para comenzar a evaluar el estado de conservación de la especie, se analizaron cinco poblaciones a lo largo de su rango de distribución en Colombia utilizando 19 loci microsatélites para realizar un estudio de genética poblacional. Diez de esos marcadores fueron útiles para revelar: (1) altos niveles de diversidad genética, (2) una estructura genética marcada de cinco poblaciones y (3) flujo de genes bajo y asimétrico entre ellas. Sin embargo, los análisis también revelaron la pérdida de diversidad genética (baja riqueza alélica) y cuellos de botella recientes en algunas poblaciones. Esos indicadores perjudiciales identificados están evidenciando una disminución de las poblaciones, muy probablemente relacionada con las actividades antrópicas. Estas cinco poblaciones corresponden a cinco Unidades de Manejo Independientes. Los resultados de esta investigación nos permiten proponer lineamientos de manejo y conservación para estas poblaciones en la ecorregión del Orinoco.

Northwest Atlantic leatherback (Dermochelys coriacea) sea turtle populations are endangered and have low hatching success compared to other sea turtles. Hatchling survival is an important element of their conservation. This longitudinal study assessed developmental phase and pathology of leatherback embryos and hatchlings at Sandy Point National Wildlife Refuge (SPNWR) on St. Croix, US Virgin Islands, in 2019 to identify patterns in mortality and lesions across a nesting season, and to make regional comparisons. Hatching and emergence success averaged 63.6% and 56.6%, respectively, and both differed significantly by month. ‘Breakout’ analysis was conducted on 41 nests and showed a preponderance of unhatched eggs lacking grossly evident embryological development (52%). Necropsies were performed on 79 unhatched and dead in nest individuals from 34 nests, and most (58%) had lesions including inflammation associated with microorganisms (34%), renal mineralization (15%), mild multifocal skeletal muscle degeneration and necrosis (5%), and anatomic malformations (4%). Inflammatory lesions included chorioallantoitis, esophagitis, stomatitis, dermatitis, gastritis, and yolk sacculitis. These were associated with bacteria (n = 13), fungi (n = 4), or both (n = 7). Sex was determined histologically and was predominantly female (90%) with no males identified in nests laid after 3 April 2019. Although hatching success was higher in in situ relative to relocated nests, embryological development and lesion patterns were similar in both groups. Patterns of lesions observed in leatherback embryos and hatchlings did not differ across the season and are comparable to other Caribbean nesting sites. Future studies pairing ‘breakout’ and pathological analyses with assessments of potentially influential environmental and/or maternal factors could help develop targeted strategies for improving hatchling production.

An 8-wk mark-and-recapture study using baited fyke nets showed that native red-bellied cooters (Pseudemys rubriventris) (estimated population 738–3618) were more abundant than non-native red-eared sliders (Trachemys scripta elegans) (estimated population 256–520) in Lake Matoaka in southeastern Virginia. Red-bellied cooters have maintained a similarly large population since a prior study in 2004 with a balanced female:male sex ratio of 0.91:1, but over that time, capture of red-eared sliders has increased almost 5-fold; their size distribution is broader than that of red-bellied cooters, and their sex ratio is dominated by females (2.02:1). Persistence of native red-bellied cooters in Lake Matoaka may be challenged by the apparent ongoing growth of the invasive red-eared slider population.

Many freshwater turtles in the United States are considered species of greatest conservation need in the states in which they occur, including turtles in the genus Graptemys (map turtles and sawbacks). However, basic life-history information is still lacking for many Graptemys species, particularly details about their movements, home range, and habitat use. The objective of this study was to describe linear activity area (LAA) and basking-site fidelity for 2 federally threatened Graptemys species in Mississippi (Graptemysflavimaculata, Graptemys oculifera) via capture–mark–recapture events. For G. flavimaculata, 97 individuals (30 female, 67 male) were recaptured during the study at 3 sites. Mean LAA for females (138 ± 293 m; 0–1489 m) and males (308 ± 637 m; 0–3773 m) was statistically similar, but turtle LAAs from 2 upstream sites were longer than LAAs from a downstream site. The maximum single movement was 2877 m by a male; alternatively, many males and females were recaptured at the same basking log across multiple years. For G. oculifera, 28 individuals (14 female, 14 male) were recaptured during the study at 1 site and mean LAAs were statistically similar for females (130 ± 206 m; 4.6–747 m) and males (231 ± 357 m; 0–1310 m). Differences in LAAs among sites for G.flavimaculata may be associated with habitat differences observed among the sites (i.e., river size, hydrology, position on river continuum) or associated with different turtle densities. Basking-site fidelity appears to be strong in both species and is likely driven by deadwood persistence time and/or sexually divergent preferences in basking sites. Additional movement ecology studies are needed for Graptemys species to determine how differences in habitat, turtle densities, and deadwood interact to influence linear home ranges.

For over 40 yrs we compiled egg length, egg width, and egg mass data for turtles in order to estimate the latter from published and unpublished data for the 2 former variables. The resulting data set includes nearly 18,000 eggs for 122 species and includes species-specific graphs (with linear regression equations and correlation coefficients) of egg width vs. egg mass and egg width vs. egg mass, as well as multiple regression equations of egg mass as a function of egg length and egg width (with statistical support). It is our hope that this note will stimulate authors to report egg mass data more rigorously, but also facilitate contemporary studies of reproductive strategies in turtles with more complete and accurate data.

In the wild, prereproductive Agassiz's Desert Tortoises rarely co-occur in burrows, which we determined by tracking 83 head-started and translocated juvenile and immature tortoises with radio transmitters at least once per month between 2013 and 2022. We observed only 2 instances of co-occurrence at burrows out of 4622 locations; 594 of these locations were at burrows often used repeatedly during temperature extremes in summer and late fall and winter. One occurrence was brief and defensive, and the other transitory cohabitation.