Agassiz's desert tortoise, Gopherus agassizii, faces threats from climate change. With limited mobility to move long distances to more-suitable habitat as climate change advances, whether protecting tortoises in situ or translocating them out of harm's way, a critical conservation task is identifying refugia, lands that will remain suitable under the current climate and the projected, end of the 21st Century warming and drying. While researchers have modeled tortoise habitat suitability, they have done so at coarse scales and did not identify climate refugia that may become apparent only with a fine-scale approach. It is at that scale that managers can implement measures that will foster habitat protection for tortoises throughout their current range. In this case study, we employed fine-scale habitat suitability modeling to identify current habitat and climate refugia within and surrounding the Marine Corps Air Ground Combat Center (MCAGCC) at Twentynine Palms, California. We modeled nearly 284,000 ha of currently suitable tortoise habitat within an 858,800-ha study area. Projected maximum end-of-the-century summer temperatures could reduce the area of tortoise habitat 55% to 127,650 ha; however, almost 115,800 ha would overlap current tortoise habitat and would serve as climate refugia. Applied elsewhere, where tortoise protection must be balanced with other land uses, this approach could increase the efficacy of conservation for this threatened species. Nevertheless, until validated with field studies, habitat suitability models represent hypotheses as to current and future distributions of appropriate tortoise habitat. These hypotheses should foster additional research identifying whether tortoise densities and demographic structure are more secure and whether tortoises can adapt to shifting climates more effectively within than outside modeled refugia.

In contrast to the other Podocnemis species, Podocnemis erythrocephala (Pleurodira: Podocnemididae) is restricted to blackwater and clearwater rivers and lakes, including the Negro River basin, and several other tributaries of the eastern Amazon River basin. In order to test the effects of geographic barriers on genetic connectivity of P. erythrocephala, 10 localities sampled throughout the Brazilian Amazon basin were studied. Two hundred and forty-six specimens were sequenced for the mitochondrial control region. Analysis of molecular variance confirmed the existence of population subdivision (Φ_ST = 0.28, p < 0.001). In pairwise comparisons, the values of the fixation index Φ_ST were significant in almost all comparisons involving the São Gabriel da Cachoeira (Negro River), Jaú National Park (Jaú River), and Barreirinha (Andirá River), indicating that these populations are genetically differentiated. Genetic differentiation is most likely explained by the presence of rapids and waterfalls separating the São Gabriel da Cachoeira (Negro River) and Jaú National Park (Jaú River) populations from the remaining populations. Populations from Barreirinha (Andirá River) were also genetically differentiated, providing support for the hypothesis that the Amazon River is a geographic barrier for this species. Although distributed over a large geographic area, the remaining 7 localities were not differentiated from one another (p > 0.005), suggesting that these localities are part of a panmictic population distributed throughout the central Amazon basin. We recommend that the 4 structured populations be treated as separate management units.

Fossils from paleocoastal deposits in northwestern Florida represent at least 3 pleurodire taxa. Biochronologic and paleoclimatic correlates suggest that the presence and absence of side-necked turtles in Florida was synchronous with global climatic shifts in the middle to late Paleogene and early Neogene. The oldest pleurodire record in Florida is from the end of the Greenhouse World in the middle to late Eocene, followed by a hiatus of ∼ 11 million yrs during the onset of the Icehouse World in the early Oligocene. Their sojourn in Florida during the latest Oligocene (25–24 Ma) was concurrent with a brief late Oligocene warming (LOW), and a subsequent hiatus in the early Miocene (∼ 24–18 Ma) was contemporaneous with global cooling. Their resettlement and most populous occurrences in Florida during the middle to late Hemingfordian through early Barstovian (∼ 18–15.5 Ma) coincided with the Middle Miocene Climatic Optimum (MMCO), a significant global warming event. Pleurodires are indicators that paleoclimate in the southeastern United States was frost free during the Eocene, LOW, and MMCO with air and water temperatures warm enough to support these generally cold-intolerant turtles. A small-bodied podocnemidid existed in the Cucaracha Formation (∼ 19.05–18.8 Ma) of Panama during the early Miocene pleurodire hiatus in Florida, and this or a closely related taxon later dispersed into Florida by the early Barstovian, when temperatures were suitable during the MMCO. Previously reported pleurodire fossils from the temporally mixed Lee Creek Mine of North Carolina are most likely middle Miocene in age when pleurodires were common in the Atlantic Coastal Plain of the southeastern United States. The presence of pleurodires in the Seaboard Local Fauna could help constrain the age of the fauna to younger than 18 Ma and probably closer to 17 Ma based on hypothesized paleoclimate at that time. A pleurodire from the middle Eocene Point “A” Dam site in southern Alabama may represent a late occurrence of the Bothremydidae.

In the Rio Negro, the third-largest tributary of the Amazon, many turtle species have been important commercial and protein resources for centuries for populations of humans living in the region. For many years, this had been a sustainable activity, but nowadays the outlook for turtle populations in the Amazon is unfavorable due to increasing hunting pressure. Based on 20 yrs of conservation work in the Amazon, we report on the pressure faced by turtle populations in the area and report a sustainable chelonian exploitation alternative developed in the Rio Negro region. We describe the materials and the hand processing artisans use to transform natural resources into artworks. Based on this community program model, we discuss the current government support to local communities of the Rio Negro and provide insights on the application of this economic alternative to substitute for turtle commercialization in the Amazon. The outcomes of this manuscript have direct applications for environmental managers, nongovernmental organizations, and policymakers in Brazil and aim to call government and environmental managers to promote turtle conservation in the Amazon, securing economic safety for local communities.

In species with temperature-dependent sex determination, the embryo commits to its sexual fate during a time window called the thermosensitive period (TSP). Although substantial research has focused on the effect of the temperature during this canonical TSP, the effect of temperatures experienced before this time (pre-TSP) on the onset and duration of the TSP is less understood. Here, we incubated eggs of the endangered Magdalena River turtle, Podocnemis lewyana, under 3 relatively constant temperatures and 6 shift-twice treatments. Constant treatments included two 100% masculinizing temperatures that fostered a relatively slower and faster embryo development and one 100% feminizing temperature. The shift treatments included a masculinizing temperature and later a feminizing temperature for a period of time at different incubation stages. Sex ratios were determined by a geometric-morphometric sexing approach developed for this species and validated by gonadal histology. This technique is a nonlethal sexing alternative; thus, it contributes to the conservation of this endangered species. The sex ratios obtained under constant temperatures were more feminized than the sex ratio of another population native to a warmer climate. Shift-twice experiments revealed that pre-TSP temperatures affected the duration of the TSP and as such influenced sex determination. Specifically, at 29°C pre-TSP, the TSP lasted 20 d (28% of the incubation period), whereas at 31°C pre-TSP, the TSP was extended for 30 d (52% of the incubation period). An approximation of developmental stages based on the congeneric Podocnemis expansa is provided. Conservation programs should monitor temperatures throughout the entire incubation period; otherwise important effects on sex ratios and other traits may be obscured.

Unique among turtles as the only exclusively estuarine species, the diamondback terrapin's (Malaclemys terrapin) life history predisposes it to impacts from humans both on land and in the near-shore environment. Terrapins are found in salt marshes and mangroves along the Atlantic and Gulf coasts from Massachusetts to Texas. Whereas previous dietary studies have elucidated terrapins' role in temperate salt marsh food webs, food resources for terrapins inhabiting subtropical mangrove habitats have not been studied. We examined dietary resource use for diamondback terrapins in subtropical mangrove creek and island habitats within Everglades National Park, Florida, to determine foraging strategies of terrapins inhabiting south Florida (SF) mangrove systems. Fecal analysis revealed 6 categories of food items, with gastropods, crabs, and bivalves being the dominant food items. Multivariate analysis revealed differences in food sources based on habitat more so than by terrapin size class. Our results revealed that like their counterparts in temperate salt marshes, SF terrapins consume similar prey categories but with different species and abundances comprising each category.

Turtles face unique conservation challenges in modern modified river systems. Despite their ecological importance, gaps in knowledge still exist that may hinder their conservation. Turtle by-catch data from the US Army Corps of Engineers' Long-Term Resource Monitoring Program were analyzed for 5 turtle species (false map turtle, Graptemys pseudogeographica; red-eared slider, Trachemys scripta; common snapping turtle, Chelydra serpentina; smooth softshell turtle, Apalone mutica; and spiny softshell turtle, Apalone spinifera) to better understand macrohabitat and mesohabitat use. These species demonstrated differences in habitat use between various macrohabitats, substrata, velocity classes, and depth classes. Common snapping turtles and spiny softshell turtles were captured most often in tributaries, whereas red-eared sliders were captured most often in tributaries and closed side channels. Smooth softshell turtles used open side channels and unstructured main-channel borders most often. False map turtles were found in a variety of macrohabitats, but catch was highest near main-channel wing dikes. Shallow, low-velocity habitat seems most important to turtles. Turtle-specific sampling methods should be employed to learn more about turtles in the middle Mississippi River.

The long-necked turtle Chelodina mccordi is considered Critically Endangered under IUCN Red List criteria. In Timor-Leste, the subspecies Chelodina mccordi timorensis is restricted to a small area of lacustrine habitat near the eastern tip of Timor around Lake Iralalaro in the Lautém District. We collected information on C. m. timorensis biology and harvest and assessed current threats and community perceptions. Data were collected during 2 surveys (February and July 2014) around Lake Iralalaro in Nino Konis Santana National Park. Threats were identified by direct observation, and local perceptions were recorded during expert interviews. Human harvest is the main threat in the area. Animals are captured using fishing line, are located using a bamboo stick in shallow water to probe the mud, or are captured by hand at the edge of the lake or under dry grass. Turtles are captured mainly during the dry season (April to October). Most experts identified C. m. timorensis under 2 different names according to the color (staining) of the plastron (veu = yellow and clear; sepe veu = dark and red). Local perspectives as to the population status of the turtle (stable, declining, or increasing) varied between 2 villages. Factors that may be reducing the capacity of this turtle to survive human harvest include predation by pigs and dogs. Fire and climate change are also likely to be important factors resulting in declines.

Bioko Island's southern beaches are important nesting sites for marine turtles in the Gulf of Guinea region. In this study, we present data on the 4 species of sea turtles nesting on 5 nesting beaches (19 km) of Bioko Island, from 2000 to 2014. A total of 43,860 leatherback (Dermochelys coriacea), 16,778 green (Chelonia mydas), 1731 olive ridley (Lepidochelys olivacea), and 85 hawksbill turtle (Eretmochelys imbricata) encounters, defined as the number of tracks, were recorded on Bioko's southern beaches. Since 2008, the estimated number of leatherback females ranged from 42 to 444, green turtles from 63 to 649, and olive ridley turtles from 22 to 53 annually. This study presents the first extensive tagging program on Bioko Island, where 790 leatherback turtles were tagged with Passive Integrated Transponder tags from 2008 to 2014. Only 6.1% of the tagged turtles returned to nest again with a remigration interval of 3–4 yrs. In addition, 279 green turtles were flipper-tagged in the 2013–2014 nesting season. Overall, the total number of leatherback turtle encounters decreased annually from 2000 to 2014. These declines may be attributed to adult turtle captures in commercial fisheries operating in the Gulf of Guinea and turtle take in local artisanal fisheries. On the other hand, olive ridley encounters increased from 2000 to 2014. The construction of a paved road from Luba, the second largest city on Bioko Island, directly to the nesting beaches is now set to dramatically alter human interaction with nesting turtles. These long-term data confirm the importance of Bioko Island's nesting beaches for the Southeast Atlantic and fill a critical need for sea turtle conservation in a data-deficient, yet globally significant, area.

Marine turtles in the open ocean often forage in areas of enhanced productivity, but how they locate those sites and what they do once there is poorly understood. One possibility is that odors from prey might be informative. We explored those possibilities in laboratory experiments using juvenile marine turtles. We analyzed responses to an airborne by-product of predation (dimethyl sulfide or DMS) and to airborne and waterborne odors made from extracts of fresh prey (squid, jellyfish, penaeid shrimp, and algae [Sargassum spp.]). Observations were made in a seawater-filled arena containing an enclosed air space. Airborne odors were delivered across the water surface and waterborne odors were introduced as extracts into the water. Tethered loggerheads (Caretta caretta) and leatherbacks (Dermochelys coriacea) failed to swim “upwind” in the presence of any airborne odor, suggesting that these stimuli, alone, do not evoke orientation from a distance. Free-swimming loggerheads and green turtles (Chelonia mydas), presented with either an airborne or waterborne squid odor, directed bites at the tank walls, at one another, and (most frequently) at a stationary visual stimulus (a small plastic sphere) anchored under water. DMS did not evoke a comparable response. We conclude that close to productive hot spots, both air- and waterborne prey odors elicit a similar visual search for underwater prey targets. A review of the literature suggests that at a distance, juvenile turtles might use magnetic maps to locate areas that include sites of greater oceanic productivity.

The majority of green turtle (Chelonia mydas) nests in the Mediterranean basin are found on the eastern Mediterranean beaches of Turkey. There are relatively few studies on the sex ratio of green turtle hatchlings for Turkey. In this study, 12 nests on the Sugözü beaches were equipped with temperature data-loggers during the nesting seasons of 2008 and 2009. Temperatures for the entire incubation period and for the middle third were close to the pivotal temperature around 29.0°C. The average incubation duration for nests with known temperature was 52.8 d. An assessment of incubation durations together with histological analysis of 188 gonad samples collected from 103 nests revealed a pivotal incubation duration of 54.3 d and constant temperature equivalent conversion revealed 54 d. This value was identified for the first time for green turtles on the beaches of the eastern Mediterranean in Turkey based on 196 nests with known incubation duration; these nests showed a female-biased sex ratio in 2008 and 2009 (with 54.9% and 56.5%, respectively). Using incubation duration can increase sample size and therefore accuracy of sex ratio predictions without any hatchling sacrifice.

We analyzed 410 nest locations from 150 individual nesting hawksbill turtles (Eretmochelys imbricata) on the northeastern Brazilian coast during 8 nesting seasons from 2006 to 2014 to evaluate individual nesting preferences. We determined the consistency of nest site choice within and between nesting seasons for open sand and vegetation nest microhabitats and also for nest site distances from the current waterline, highest spring tide, vegetation line, and position along the beach. We found that behavioral consistency within seasons was more robust than between seasons. This suggests that a decrease in the consistency of nest site choice may be related to progressive landscape changes in the nesting environment, driving behavioral flexibility in nesting preferences.

Kemp's ridley (Lepidochelys kempii) is the most endangered of the sea turtles. Its female population in the Gulf of Mexico suffered a major setback sometime between the ends of nesting seasons in 2009 and 2010. Prior to that, annual nests (i.e., clutches laid by multiple year-classes of nesters) at the female population's index beach in Tamaulipas, Mexico were increasing exponentially, the result of more than 4 decades of cumulative conservation efforts on land and at sea. Annual nests dropped 35.4% in 2010 and remained well below predicted levels through 2014, and annual hatchlings released (both sexes combined) also were lower in 2010–2014 compared with those in 2009. We conducted novel analyses of an available 1966–2014 time series of annual nests and annual hatchlings released on the index beach. We examined 1) the relationship between time-lagged annual nests during years 1986–2014 and cumulative hatchlings released by years 1976–2004, respectively, assuming female minimum age at maturity of 10 yrs, and 2) the time-series of time-lagged annual nests during 1986–2014 divided by cumulative hatchlings released by 1976–2004, respectively, under the same assumption. Both metrics showed extraordinary downward departures in 2010–2014, instead of expected increases. Although causes of the population's setback have not been determined with certainty, we suggest that the most expedient way to restore this population's growth would be to translocate more clutches to protective corrals, leaving fewer in situ where their survival is reduced. It could take at least 10 yrs before results of such a change in conservation practice become evident.

Twenty-one immature Kemp's ridley sea turtles (Lepidochelys kempii) were collected following incidental capture or entanglement in recreational hook-and-line gear during 2005–2008 in Galveston County, Texas, United States. Turtles consumed primarily swimming crabs (common blue crab, Callinectes sapidus, and Callinectes spp.), walking crabs (calico box crab, Hepatus epheliticus; mottled purse crab, Persephona mediterranea; and hermit crabs), and polychaete worm tubes. Macroalgae (Sargassum spp.) was also consumed by nearly half of the sampled turtles, presumably incidentally and likely as benthic detritus. The upper Texas coast and local fishing piers provide diverse foraging opportunities for immature Kemp's ridleys but also put the species at risk for interactions with human activities, including gear interactions and ingestion of anthropogenic debris.

A head-started Kemp's ridley sea turtle (Lepidochelys kempii) was documented nesting on South Walton Beach, Florida on 25 May 2015. This record supports the possibility that exposure to Florida waters after being held in captivity through 1–3 yrs of age during the head-starting process may have influenced future nest site selection of this and perhaps other Kemp's ridley turtles. Such findings could have important ramifications for marine water experimentation and release site selection for turtles that have been reared in captivity.

The ability for animals to become temporarily immobile via external stimulus is known as tonic immobility (TI) and has been widely described among different taxa. However, TI is poorly documented in turtles. We demonstrate TI in newly emerged green turtle (Chelonia mydas) hatchlings in relation to potential practical applications and discuss the methodology of how to induce TI. On average, combining all clutches sampled, TI induced green turtle hatchlings to remain immobile for 25 ± 12 sec; thus, we argue that in this state of immobility, researchers and conservationist can safely obtain quantitative variables (e.g., animals' weight and morphological measurements without forceful stressing or harming the animal).

We describe infestation of hawksbill turtle (Eretmochelys imbricata) nests by insects on Pipa beach in the municipality of Tibaudo Sul, Rio Grande do Norte, Brazil in January and June 2011. The mean number of live hatchlings (83.96 ± 43.31) was higher in nests unassociated with vegetation, although it is important to consider that a number of parameters other than proximity to vegetation may also affect nest success.

Hematologic and biochemistry ranges were established for 31 clinically healthy green sea turtles (Chelonia mydas) incidentally captured in artisanal fisheries in Sechura Bay, Peru. Postcapture stress may have influenced heterophil values and glucose concentration. Sechura Bay provides abundant dietary protein affecting urea and glucose values.

Johann Friedrich Eschscholtz published two herpetological titles, the first in a journal named Quatember. Until now, this paper, which contains descriptions of three sea turtle taxa, including Chelonia olivacea, has been overlooked, and the nomenclatural implications have been ignored. The Quatember paper preceded, and has precedence over, Eschscholtz's better known Zoologischer Atlas, and therefore is the earliest description of C. olivacea. However, Plate III of the Atlas remains the earliest illustration for what is today called Lepidochelys olivacea.