Chersina angulata females ovulate sequentially and oviposit multiple, mostly single egg clutches from early autumn (March) throughout winter and spring until early summer (December). No matter when eggs are laid, they usually hatch in autumn (March/April). Evidence based on circumstantial observations also demonstrates that wild and captive females occasionally retain the last clutch of the season until completion of embryonic development in autumn, conforming to the accepted definition of viviparity in reptiles. However, developmental progress throughout the year and embryonic stages of freshly deposited last clutches has not yet been reported. We candled all eggs laid from April to December in a captive colony of C. angulata in an outdoor enclosure in Cape Town, South Africa, to estimate developmental progress and embryonic stages. In all eggs laid during autumn, winter, and early spring (March to mid-October), vitelline blood vessels, indicating development had progressed to somite formation, only started to become visible at approximately the same time in late November. Until mid-spring, embryonic development of those eggs had been arrested prior to somite formation; the embryos underwent diapause until, presumably, increasing temperatures reinitiated development. Development then progressed throughout summer until the hatching stage was reached in early autumn. However, eggs laid in late spring (mid-October to November) skipped diapause, and embryonic development progressed without interruption, demonstrating that, depending on the season of oviposition, diapause in C. angulata is facultative. Candling of an egg laid in late December showed that, prior to oviposition, embryonic development inside the female had already advanced to an embryonic stage with well-developed vitelline circulation corresponding to Yntema stage 12. Contrary to the generally accepted wisdom that intrauterine embryonic development in the order Testudines is always arrested at the gastrula stage, embryonic development inside the female had already reached the stage of somite formation. This phenotypic plasticity in the expression or abolishment of preovipositional developmental arrest represents a transitional stage in the evolution towards viviparity.

This study examined population ecology parameters for a southern population of the tent tortoise (Psammobates tentorius tentorius) in the Karoo. We found a relatively low density of tortoises (49 tortoises/km²) skewed to adults with a 1:1 sex ratio. The tortoises' contrasting dark and light carapacial patterns create crypsis with the disruptive shadows cast at the base of vegetation (mostly shrubs) where the tortoises seek refuge. The largest female was 14.7 cm, which makes her approximately 42 yrs old. The largest male was 11.6 cm, which makes him approximately 42 yrs old. We can distinguish males and females at carapace lengths of approximately 8–10 cm, when the tortoises are approximately 8–10 yrs old. Psammobates t. tentorius is a sexually size-dimorphic species in which adult females are significantly larger than are males. Selection for body shape and size appears attributable to fitness between the sexes (e.g., egg production and size in females, and opportunities to mate by males). We characterize this first group of nominate tent tortoises for future comparisons with other population. The study provides critical baseline information for the long-term management and conservation of this species, and adds to our understanding of the fauna of the Succulent Karoo.

We began developing our Geometric Tortoise Ecosystem Preserve in 2015. At the same time, we began a mark–recapture study to detect changes in the population size through time to inform our management practices. We now have data through 2021. Mark–recapture analysis gives a population size of between 800 and 1200 individuals. It is the last remaining substantial population. Using Lande's classification of 1933 of stochastic influences on demography, we find that 1) demographic stochasticity is not a problem, as the population is large enough and consists of individuals whose home ranges overlap; 2) environmental stochasticity is important mainly through variations in annual rainfall, including severe droughts; and 3) catastrophes occur in the form of wildfire that can destroy a local population. Taken together, these environmental effects can cause large changes in population size, making this species at risk of local extinction. If it were to go extinct, there are no other adjacent populations that could be used to recolonize our preserve. Therefore, we conclude that head starting is necessary to safeguard the population.

In April 2001, 187 illegally collected and confiscated pancake tortoises (Malacochersus tornieri) were released in Mzinga and Irima rocky hills in the southern part of Tsavo East National Park, an area where there were no free-ranging wild populations. The aim of this study was to establish the status of this introduced population and identify the lessons that can be learned to guide future reintroductions. Prior to release, the specimens were marked by cutting numbered notches on the marginal scutes based on a coding system. In June 2022, a revisit to the April 2001 release sites was done to retrace this population in an effort to both recapture some of the individuals or find a new juvenile cohort. After 21 yrs, only 15 individuals were found—10 of which were recaptures, representing 5.3% of the total release population. Of these 10 recaptures, only 2 had clear marks and could be traced to a specific number that showed they were mature adults when released. The 8 recaptured tortoises did not have marks and their carapaces were either worn out to plain brownish or had faded dark marks. It was assumed that these were likely those young specimens released with a carapace length of less than 130 mm and that the notch mark disappeared during body growth. Using a combination of the carapace length, carapace color pattern, and absence of notch marks, 5 specimens were confirmed to have been born after the initial release, representing a new cohort. Pancake tortoise carapace growth in captivity has been found to be very fast, and specimens reach sexual maturity at 150 mm and in about 6 yrs, and after this no significant carapace growth occurs. This fast growth rate is not possible in the wild, where there are long periods of inactivity during the dry season. Hence, it is assumed that growth in captivity should be twice or thrice that in the wild. Therefore, using our data from new and recaptured tortoises, and comparing it with the growth rate and color change in captive specimens, it is possible to estimate the age of wild individuals. This study also shows that there is carapace color and pattern change with carapace growth with age, until a time when the color pattern starts fading with little or no change in carapace length. The study found only a very small proportion of the total number of individuals released. This could be attributed to the fact that the majority of the individuals (82.9% being mature adults, > 130 mm) were about 15–20 yrs old, and 21 yrs later they likely would have naturally died after exceeding their lifespan of about 25 yrs. Others may have died of predation before breeding. What is clear is that, despite the low number of encountered individuals from new cohorts, reintroduction of confiscated tortoises is a viable initiative to boost depleted wild populations. Finally, given that there are viable populations at captive breeding facilities, it is highly recommended that the international pet trade should focus on getting captive-bred specimens and leave the wild ones to boost local tourism.

In a study to reduce Mojave Desert Tortoise (Gopherus agassizii) mortality along roadways, we tested the feasibility of structures that discourage tortoises from 1) walking or “pacing” along barriers or 2) crossing areas where gates or openings occur. The diversion designs we tested (one straight and one curved structure, each 7.6 m long) deflected tortoises away from fences at nearly the same rate as tortoises who continued walking along barriers despite the diversion (36.8% vs. 35.7%). No “tortoise guard” structures that we tested, similar to cattle guard structures, were 100% effective at preventing tortoises from crossing the opening. We identified essential characteristics of an effective “tortoise guard” such as minimum gap sizes in the structure and a construction design that allowed a tortoise to climb out of a trench under the structure.

Camera traps are very useful tools in determining the presence/absence of rare and cryptic species while shedding light on behavioral traits. Passive infrared triggered cameras are routinely used in homeothermic animals, but in ectothermic reptiles, this surveillance method has proven highly unreliable. As part of the conservation goal to provide better understanding and protection for the critically endangered freshwater turtle Batagur baska, we investigated their largely unknown nesting behavior and tested video-based motion detection by comparing 2 different camera-trapping systems and their settings under controlled conditions at the Vienna Zoo. A pixel-based video surveillance camera was superior to a camera trap with motion sensor. The surveillance camera allowed reliable motion detection at sensitive settings, and video capture precision could be enhanced by marking the terrapin with reflective tape. This video surveillance camera was then deployed over 2 breeding seasons (2019 and 2020) in the conservation breeding project of the northern river terrapin (B. baska, Gray 1830) in Bhawal National Park in Bangladesh. Analysis of video recording demonstrated for the first time that female northern river terrapins nested on average for a period of 1.5 hrs and produced a single clutch per year. Results indicate that females inspect sandbanks and visit suitable nesting sites several times before egg deposition, suggesting that nest-site selection is not random in B. baska. In addition, water temperature measurements of the breeding ponds in 2 captive breeding sites of the B. baska project showed an annual average temperature decrease to 168C–188C during the mating season and an average increase to 288C–318C before the nesting season. Temperatures on nesting nights vary between the 2 breeding sites and differ between nesting events within each site, suggesting that overall seasonal temperature shifts initiate the nesting periods, while other physiological and environmental factors might trigger the actual nesting event. With the help of consistent motion-triggered video recording, our study provides a first underpinning of the nesting ecology of B. baska.

The wood turtle (Glyptemys insculpta) is experiencing widespread declines throughout its range in the eastern United States and Canada. Maine has been considered a stronghold for the species due to an abundance of suitable upland and stream habitat. Furthermore, recent studies have identified Maine as a potentially important climate refuge for wood turtles. Using data collected in a 5-yr capture–mark–recapture study on a wood turtle population in central Maine, we estimate population size, apparent survival rates, population growth rates, and population viability. We also performed a sensitivity analysis to illustrate the impacts of slight perturbations to demographic rates. Our estimated total population size is 73 (95% CI = 69–85) individuals. Annual apparent survival varied across years, ranging from 80.5% to 97.5%, with females having a slightly higher survival at 94.9% (95% CI = 81.6%–97.8%) than males at 92.8% (95% CI = 77.6%–97.4%). The baseline population viability analysis model predicted a k of 0.93 (95% CI = 0.91–0.95) and a 100% probability of extinction within 150 yrs. Despite some broad permutations in our baseline demographic parameters, there were no scenarios included within our sensitivity analysis that increased the population's growth rate to a positive value. These results have implications for the long-term persistence of wood turtles in Maine and throughout their range. Our study helps fill a need for current data from this area that may be used to inform both local and regional management plans.

The Hispaniolan slider, Trachemys decorata (Barbour & Carr 1940), is a freshwater turtle of conservation interest, endemic to the island of Hispaniola. The species is currently threatened by habitat destruction, hybridization with invasive species, and commercial harvest. However, the consumption of the Hispaniolan slider by human populations has received little attention. During the winter of 2017–2018, we conducted a survey to document the commercial use of freshwater turtles at Trou Caïman, one of the major wetlands in Haiti, based on interviews with 72 people representative of the local community. The strong demand for freshwater turtles from people living around the lake was related to classical uses such as meat consumption, artisanal jewelry, or the pet trade, but also to more-peculiar ones such as cleaning of hand-dug water wells, voodoo ritual, and folk medicine. Our results illustrate the importance of considering the socio-cultural context for designing efficient conservation plans for T. decorata in Haiti. We particularly discuss the pros and cons of developing turtle farming, possibly in conjunction with rice agriculture, as a potential solution to preserve the integrity and future of T. decorata.

In China, Hainan Island is a priority area for turtle conservation because of its biodiversity. Over the years, errors in turtle taxonomy and distribution have been made in the scientific literature, perpetuating into relevant laws and government documents and affecting conservation and management. In the present article, we describe the species of nonmarine turtles on Hainan Island, China, based on literature, museum specimens, and field surveys during the past 27 yrs. Historically, 23 nonmarine turtle species were recorded on Hainan Island. Among them, 9 species should be removed due to errors: 5 species are not naturally distributed on Hainan Island (Manouria impressa, Sacalia bealei, Cuora flavomarginata, Mauremys nigricans, and Mauremys reevesii), 3 are invalid hybrids (Ocadia philippeni, Sacalia pseudocellata, and Cuora serrata), and 1 is a synonym of another species (Mauremys megalocephala is a synonym of M. reevesii). In addition, of the 3 new species recorded from Hainan Island (Sacalia insulensis, Pelodiscus variegatus, and Pelodiscus parviformis), S. insulensis replaces Sacalia quadriocellata, P. variegatus is valid, and P. parviformis is likely an error. Therefore, there should be 12 nonmarine turtle species naturally found on Hainan Island: Platysternon megacephalum, Cuora galbinifrons, Cuora mouhotii, Cuora trifasciata, Geoemyda spengleri, Mauremys mutica, Mauremys sinensis, S. insulensis, Palea steindachneri, Pelochelys cantorii, Pelodiscus sinensis, and P. variegatus. Clarifying the presence and distribution of nonmarine turtle species will provide a reference for future research and practical guidance for conservation management on this turtle-rich island.

In general, chelonians are widely distributed, occupying areas with significant environmental variation, which may lead to great variations in their ecology such as morphological characteristics, sexual dimorphism, population structure, and reproductive aspects. In this context, our main objective was to characterize populations of Phrynops geoffroanus and Mesoclemmys tuberculata in areas of Caatinga and Atlantic Forest in Northeast Brazil to evaluate the relative importance of intraspecific factors and environmental differences in determining ecological parameters. Samples were collected in semiannual surveys (dry and rainy season) over a year. We measured morphometric variables and the mass of captured animals and correlated the reproductive pattern with the season and adults' reproductive condition. We did not find significant differences in size, maximum straight-line carapace length (SCL), or body mass of both species, regardless of sex, between the studied environments. We recorded reproductive males of both species throughout the year (dry and rainy seasons), and testicular volume was positively correlated with SCL. In contrast, eggs and oocytes were recorded exclusively in females collected during the rainy season. However, we found eggs and vitellogenic follicles simultaneously, indicative of multiple clutches in a reproductive season. In P. geoffroanus, we did not find a significant relationship between clutch size and female SCL, although egg volume was positively correlated with SCL. In M. tuberculata, we did not find a meaningful relationship between any of these parameters. Finally, the ecological parameters evaluated differed considerably between species and environments, presenting similar patterns in Caatinga and Atlantic Forest.

We investigated methods for reducing highway-caused mortality of Mojave Desert Tortoises (Gopherus agassizii) using barriers at the Desert Tortoise Conservation Center, located near Las Vegas, Nevada. Experiments tested effectiveness of various barriers of different heights and made of different construction materials, sex-dependent behaviors including rate of escapes, appropriate height of a barrier, and adverse effects on other sympatric vertebrate species including potential entrapment. Informed by analyzing previous investigations, we tested captive adult desert tortoises (midline carapace length ≥ 180 mm) within enclosures made from 8 different common construction materials, quantified behavioral responses of individuals over several (4–14) days, and identified sex-dependent responses to these barriers. Both sexes pushed against see-through barriers more than solid barriers (58% males, 67% females) and males reversed direction of pacing more often than females (56%). Pen escapes related to pacing reversals and were generally by males. Direction reversals and escapes occurred mostly with wire mesh designs and low (20-cm) solid barriers. Frequency of body contact was not linearly correlated with larger mesh sizes. Solid barriers appear to offer the best deterrent but are more expensive. Animals that escaped in trials lasting several days were larger than average size and often escaped more than once. Tortoises escaped at weak points in barriers, such as gaps with the ground, pen corners, breaks in material, or by climbing over the barrier. In testing minimum effective barrier height for 3 types of barrier materials, none climbed over at 46 cm, 5 climbed over at 30 cm, and 19 others climbed over at lower heights. We observed native species interactions with our barrier enclosures (n = 70) and compared morphometric measurements of common desert reptiles vs. barrier dimensions. These data suggested that different barrier types preferentially affect specific sizes of animals although we observed no mortality. While solid barriers stop all reptiles, wire meshes entrap reptile species smaller than mesh size (such as Callisaurus draconoides and Uta stansburiana) and stop larger species (such as Dipsosaurus dorsalis and Coluber flagellum). Morphometric measures of juvenile tortoises indicated that they could pass through the 2 largest wire mesh sizes we tested.

Chersina angulata egg retention times differ among sequentially ovulated eggs from February to November, being shorter in eggs ovulated in October and November than in eggs ovulated in February, April, May, and July. More time is required to achieve eggshell calcification from July to October than from March to June. In most instances (71%) females lay their eggs when the eggshell still appears relatively thin on the radiographs, with only few eggs becoming more prominently calcified prior to oviposition.

Robust morphological data are key to systematic and ecomorphological studies, but Karoo dwarf tortoises (Chersobius boulengeri) are difficult to sample due to scarcity and secretive behavior, resulting in scant published recordings of shell dimensions based on data gathered at many locations over many years. We sampled, for the first time, a single population of Karoo dwarf tortoises in 2018–2020 and report shell dimensions for 52 males, 37 females, and 5 juveniles. Male and female shells were dimorphic in size, volume, and shape, and a comparison with speckled dwarf tortoises (Chersobius signatus) suggests subtle congeneric differences in sexual dimorphism.