Hatchling river turtles (Smooth Softshell Turtles, Apalone mutica; Spiny Softshell Turtles, Apalone spinifera; Northern Map Turtles, Graptemys geographica; False Map Turtles, Graptemys pseudogeographica; and Ouachita Map Turtles, Graptemys ouachitensis) were released in a variety of settings to help place orientation and dispersal from nests in the context of nest site selection by females and juvenile recruitment habitat. Visual cues associated with near open or far dark horizons were the primary environmental cues used during initial orientation and dispersal of the hatchling river turtles. On a river beach, hatchlings of both species of Softshell Turtles dispersed toward the open horizon of the nearby river. In contrast, hatchlings of all 3 species of Map Turtles on the same beach dispersed toward the near dark horizons of a forest that led them away from the river. Hatchling Map Turtles of all 3 species released in autumn and Northern Map Turtles also released in spring at a field arena dispersed toward near dark horizons of pine (Pinus spp.) and deciduous trees to the north and south of the arena (directions that were parallel to the Mississippi River). At a site in upland prairie habitat with no nearby wetlands, hatchlings of all 3 species of Map Turtles dispersed to the north toward near dark horizons of an oak (Quercus spp.) forest rather than toward more distant dark horizons of mixed oak and pine trees. At a lowland prairie site where no near dark horizon was visible, Northern Map Turtles dispersed toward 2 far dark horizons that were ∼ 230 m to the north (a pond surrounded with trees) and to the south (an area of large deciduous trees at the west end of a windrow of pine trees), but not toward the large riparian wetland 280 m to the west. The bimodal dispersal pattern toward 2 equidistant dark horizons within 230 m but not toward the riparian area 280 m to the west suggests that the perception distance for hatchling Northern Map Turtles is between 230 and 280 m. Dispersal of a combined sample of naïve hatchling False Map and Ouachita Map Turtles released in a mature corn field was not different from random, but the directions taken by the majority of hatchlings were to the north and south across corn rows that may be the closest match to dark horizons used for dispersal in typical habitats.

Changing climate is affecting life all over the world. The loggerhead turtle (Caretta caretta) is one of the most vulnerable turtle species to climate change, particularly with regard to sex determination being affected by high temperatures in most nesting areas, such as the Cuban archipelago. As yet, species information is scarce for the Cuban archipelago as a whole. This study provides information about loggerheads in order to determine the possible effects of climate change on this species, especially in Guanahacabibes. We monitored 10 beaches along the southernmost coast of the Guanahacabibes Peninsula for 18 yrs (1998–2015), from May to September of each year, to determine nesting activity and density. Females were measured and tagged and the remigration interval was determined. Temporal variation was reflected in apparent peaks in reproductive activity on a biennial cycle. We found intraseasonal variation with the highest nesting activity in June, with a 15% increase in nesting activity in the second half of that month. Reduction in clutch size, incubation period, and hatchling size, as well as a potential feminization of hatchling production, indicates a possible effect of climate change in reproductive success. Our results are a first attempt at characterizing Guanahacabibes populations and have great value for establishing conservation priorities such as the protection of the nesting females and control of incubation environment in the face of global climate change within the context of national management plans.

Managers making decisions may benefit from a well-informed understanding of a species' population size and trends. Given the cryptic nature and habitat characteristics of the western pond turtle (Emys marmorata), however, imperfect detection may be high and population estimates are frequently varied and unreliable. As a case study to investigate this issue, we used temperature dataloggers to examine turtle behavior at 2 long-term monitoring sites with different hydrological characteristics in Sequoia National Park, California, to determine if common stream-survey techniques are consistent with site-specific turtle behavior. Sycamore Creek is an intermittent stream that dries up every summer while the North Fork Kaweah River flows year-round. We found that while turtles spent most of the recorded time in the water (55% in Sycamore Creek and 82% in the North Fork Kaweah River), the timing of traditional surveys only coincided with the turtles' aquatic activity in the North Fork Kaweah River. At Sycamore Creek, turtles were most likely to be in the water at night. In contrast, failure to detect turtles in North Fork Kaweah River is likely owing to the larger size and complexity of the underwater habitat. In both streams, turtles were also more likely to be in the water in the weeks leading up to important changes in hydroperiods. Our findings illustrate the effects that differences in water permanence can have on turtle behavior within the same watershed and how phenotypic plasticity may then affect detection during surveys. Our study highlights the importance of tailoring survey practices to the site-specific behavioral traits of the target species.

The nesting population of leatherback sea turtles at the Sandy Point National Wildlife Refuge (SPNWR), Sandy Point, St. Croix, US Virgin Islands, has been comprehensively studied since 1981. Nesting and hatching data are reported here for the first 30 yrs of the research and conservation project. Because of intense nest relocation and conservation efforts, the population initially showed a steady increase in numbers, with the most dramatic rise occurring between 1997 and 2001. In spite of continued efforts, however, this recovery began to stall in the decade from 2000 to 2010. Analysis of nesting data, including specific reproductive parameters such as recruitment rate, remigration interval, and productivity (number of nests laid, hatching success) during this time frame, in conjunction with historical data, provided an opportunity to assess the contribution of these factors to the population dynamics at Sandy Point. Annual reproductive data demonstrated that regardless of overall nesting numbers, odd years consistently exhibited higher nesting numbers (115.6 ± 18.58) than even years (68.4 ± 7.63) (p < 0.01). The average annual remigration interval increased over the study period with a record high of 3.41 ± 0.18 yrs observed in 2008. A steady decline in average nests laid was observed (R² = 0.84) between 1992 and 2010, with a record low of 3.60 ± 2.16 nests per turtle in 2010. Hatching success varied over the 30-yr period from a project low of 40.28% ± 23.20% in 2005 to a record high of 67.80% ± 20.31% in 1991. Mean overall hatching success for the first 30 yrs of the project was 58.50% ± 7.75%. Hatching success declined over the course of the project, and the number of hatchlings produced per turtle declined in the 2000s. These factors contributed to a decrease in population productivity and may ultimately have inhibited continued population growth. Over the study period, a stable percentage of remigrants continued to nest at Sandy Point. However, a decreased number and percentage of neophytes was observed, suggesting either a delayed or a decreased recruitment, possibly due to increased age to sexual maturity, an increased mortality of early life stages, or a change in food resources at foraging grounds. These results suggest a population that has slowed growth and that may begin to decline in the future. Further research needs to be conducted to understand possible maternal, physiological, and environmental factors that are impacting these reproductive parameters and, ultimately, affecting the population dynamics at SPNWR.

Although general descriptions of nesting in painted turtles (Chrysemys picta) are numerous, few studies have quantified the timing of the components of the nesting process, and no previous study has analyzed the factors influencing those times. The present study was conducted on the Crescent Lake National Wildlife Refuge in Garden County, Nebraska, in June 2012 and 2013 and focused on a single nesting population of female C. picta. We recorded times for the initiation of the nest foray, and the beginning and conclusion of nesting, and calculated search and construction times. Although highly variable, on average females left the marsh at 1709 hrs (n = 130), began nesting at 1745 hrs (n = 141), and finished nesting at 1915 hrs (n = 135). Search time averaged 26 min (n = 79) and nest construction time averaged 97 min (n = 104). We investigated the effects of female body size, air temperature, time of day, nest day, clutch number, substrate type, and reproductive output on these times. Smaller females nested earlier in the day, construction times were shorter in warmer temperatures, nests begun earlier in the day were completed more quickly, and nest times were longer earlier in the season and for first vs. second clutches. Soil type and measures of reproductive output had no effects on nesting times. These results suggest that temperature is a primary driver of nesting times, as these turtles exploit the afternoon–evening window of optimal temperatures, avoiding heat stress earlier in the afternoon and much colder evening temperatures as well as a presumed increase in predation risk after dark.

The diamond-backed terrapin (Malaclemys terrapin) is the only North American turtle species specialized for living in brackish and saltmarsh environments. The Texas subspecies (Malaclemys terrapin littoralis) is found along most of the Texas Gulf Coast. Previous studies on the prey and diets of Atlantic and Florida subspecies found that the diet of terrapins primarily consisted of crustacean and molluscan species, although differences in dietary composition were observed between the sexes. Furthermore, prey availability had little effect on terrapin distribution within a marsh. We examined the prey availability and diet of Texas diamond-backed terrapins. Comparisons of random locations to terrapin capture locations indicated that prey availability is not a limiting factor affecting terrapin distribution in Texas marshes, but multiple significant seasonal and locational differences in prey were detected at capture sites. Fecal analysis, using multiple metrics, indicated Gastropoda and Decapoda as major components of the diets of Texas terrapins. Plicate horn snails (Cerithidea pliculosa) and fiddler crabs (Uca spp.) were important prey items for all terrapins. There were significant differences between the diets of male and female terrapins, among seasonal diets, and among diets of terrapins captured at different marsh sites. Our prey availability findings support previous studies, but results from fecal analysis indicate a slightly different diet for terrapins than previously reported in other studies. The combined results extend the basic knowledge and understanding of terrapin diets, which will be useful for ongoing conservation and management of M. terrapin, especially the Texas subspecies.

Many species of reptiles maintain their body temperature behaviorally in a narrow range, even in the presence of considerable environmental temperature variation, by choosing microhabitats with different temperatures. In freshwater turtles, thermoregulation is generally achieved by aerial basking, even though they perform all other vital activities such as food consumption and reproduction in the water. Therefore, time budgets related to basking should be constrained and individuals should maximize the energy per unit time during basking, potentially by increasing basking frequency at noon during colder months and increasing use of basking when water temperature decreases. We analyzed basking behavior during the austral summer to study the effects of season, water temperature, and time of day in 2 South American freshwater turtles: Trachemys dorbigni (black-bellied slider) and Phrynops hilarii (Hilaire's side-necked turtle). We found that water temperature negatively affected basking frequency in both species differently; basking by T. dorbigni occurred on a diel cycle while basking by P. hilarii occurred on a seasonal level. Both species showed a bell-shaped basking frequency during the day, with more individuals basking at noon than in the morning and afternoon. However, only P. hilarii showed a significant seasonal effect on basking, with basking frequency decreasing in summer. These results suggest the thermoregulatory role of basking behavior in 2 austral turtle species and its trade-off with other vital activities.

Foraging behavior from 30 wild hawksbill turtles (Eretmochelys imbricata) was video-recorded by scuba divers on the coral reefs of Palm Beach County, Florida. A transition matrix was created to calculate the sequence and frequency of 5 behavioral categories leading to prey ingestion, and general observations associated with foraging behavior were described. Likely aided by olfaction, the hawksbills at this site employed a multistep process to preferentially locate and ingest well-concealed sessile invertebrates, notably poriferans of the class Demospongiae. Cumulatively, behavioral frequencies decreased as the sequence progressed toward prey consumption, and only a small proportion of the items handled were ingested. Highly exploratory foraging behavior may aid hawksbills to adaptively identify and prioritize dietary preferences within and among habitat types.

The ability to identify the sex of animals accurately is important in population studies. Emydid turtles (Testudines: Emydidae) demonstrate a number of sexually dimorphic characters, including head (cranial) size and structure. Field observations from a long-term study of midland painted turtles (Chrysemys picta marginata) in Algonquin Provincial Park, Ontario, Canada, suggested distinct differences in external head morphology between the sexes. We evaluated these putative sexual differences in C. picta head morphology by conducting a visual questionnaire involving human observers of varying levels of experience (novice, beginner, intermediate, and advanced). Observers were capable of distinguishing the sexes based solely on head morphology with a high degree of accuracy (between 79% and 86% success) across experience levels. Observers identified head shape as a defining character distinguishing the sexes. We suggest that visual questionnaires are a quantifiable method of assessing dimorphic characters that can be used in addition to traditional morphometrics or geometric morphometrics to demonstrate a visual, rather than simply statistical, difference among characters and sexes. Despite the breadth of research conducted on C. picta, our study is among the first to describe, assess, and discuss the functional significance of head dimorphism in this model species.

The Ogasawara Islands in Japan represent an important rookery for green sea turtles (Chelonia mydas) in the Pacific Ocean. The marine turtle population in these islands was severely depleted due to overexploitation in the 1800s; however, continuous nesting surveys starting in 1975 showed signs of a gradual recovery, and an upward trend of nesting females has been observed in recent years. The Japanese government undertook a “hatch and release project” to recover the turtle stock in 1910 as the world's first attempt of a sea turtle hatchery. A total of more than 251,000 hatchlings were released into the wild as a part of the project; however, its contribution to the recent increase in nesting females is not well understood. The increase in nesting females may be attributed to the temporary suspension of the turtle harvest and reduction of catch from 1942 to 1968, which allowed for stable production of hatchlings from natural beaches. This study documents the levels of harvest, number of nesting females, and hatchling production at Ogasawara and explores, for the first time, their influence on population dynamics of Ogasawara's green turtles.

This study was conducted in São Sebastião Channel, along the Southern Brazil Platform, and describes the occurrence of 3 species of sea turtles in the area, their main behavioral patterns, and the anthropogenic-related threats. Green turtles (Chelonia mydas) showed a preference for a site covered by Halodule spp. seagrass and hawksbill turtles (Eretmochelys imbricata) showed a preference for a sheltered bay with little wave action and the presence of rocks covered with Palythoa caribaeorum. These sites exhibited different characteristics due to the presence of ocean currents and variable habitat types in the Channel. This study enabled the description of the São Sebastião Channel as a foraging and resting area for sea turtles. We also suggest changing the category of the local marine protected area to enable better protection of turtles.

Broad variation in egg hatching success observed in gopher tortoise (Gopherus polyphemus) populations led us to investigate hatching success and other reproductive attributes within a unique, high-quality site in the eastern portion of the species' range. We documented use of a juvenile tortoise burrow as a nest site, a mean clutch size of 5.9 eggs, long oviposition-to-hatchling emergence times (96–128 d), and 73% hatching success for predator-protected eggs. Although consistent with previous reports of greater hatching success in eastern gopher tortoise populations than in western ones, hatching success at our eastern site was on the low end of values from other eastern populations, possibly reflecting above average rainfall during this study.

Loggerhead turtles (Caretta caretta) are characterized by their transoceanic migratory patterns in the North Pacific Ocean, as individuals of this species originating from nesting beaches in Japan are known to forage along the Baja California Peninsula (BCP), Mexico. The nearshore waters of BCP serve as important foraging habitat for growth and development; however, the implementation of appropriate management strategies has been hindered by the paucity of data on the biology and distribution of the species, particularly for juveniles during their developmental migrations. We report for the first time the occurrence and distribution of loggerhead turtles in Sinaloa, Mexico, in the southernmost portion of the Gulf of California.