Distribution Of Turtles Research Articles

Surveys of the Angolan coast uncover the largest olive ridley sea turtle nesting population in the Atlantic and the largest non-arribada population globally

AbstractKnowledge of the abundance and distribution of species is important for designing and prioritizing conservation and management activities. Despite numerous existing studies on the distribution and status of sea turtles, we still lack knowledge about certain populations, especially in Angola, which is considered to be the southernmost range of nesting sea turtles in the eastern Atlantic. This study provides an overview of the status, size and distribution of the olive ridley sea turtle Lepidochelys olivacea population nesting along the coast of Angola, and its relevance in the context of other olive ridley turtle nesting populations in the Atlantic. Aerial and ground surveys were conducted along 1,410 km of Angolan coastline and daily beach monitoring over 53.9 km of seven permanent study sites at a range of latitudes during 2011–2020. Angola hosts the largest olive ridley turtle nesting population in the Atlantic, and the largest non-arribada population globally. Although the population appeared relatively stable, the pressures from various threats on land (e.g. consumption of turtles and eggs) and at sea (captures in fishing gear) necessitate the development of a comprehensive management plan, improved and strengthened legislation and law enforcement, and a cohesive approach to conserving all sea turtle species in Angola.

Oceanic drivers of juvenile sea turtle strandings in the UK

Juvenile sea turtles can disperse thousands of kilometers from nesting beaches to oceanic development habitats, aided by ocean currents. In the North Atlantic, turtles dispersing from American beaches risk being advected out of warm nursery grounds in the North Atlantic Gyre into lethally cold northern European waters (e.g. around the UK). We used an ocean model simulation to compare simulated numbers of turtles that were advected to cold waters around the UK with observed numbers of turtles reported in the same area over ~5 decades. Rates of virtual turtles predicted to encounter lethal (10°C) or detrimental (15°C) temperatures (mean 19% ± 2.7 SD) and reach the UK were consistently low (median 0.83%, lower quartile 0.67%, upper quartile 1.02%), whereas there was high inter-annual variability in the numbers of dead or critically ill turtles reported in the UK. Generalized additive models suggest inter-annual variability in the North Atlantic Oscillation (NAO) index to be a good indicator of annual numbers of turtle strandings reported in the UK. We demonstrate that NAO variability drives variability in the dispersion scenarios of juvenile turtles from key nesting regions into the North Atlantic. Coastal effects, such as the number of storms and mean sea surface temperatures in the UK, were significant but weak predictors, with a weak effect on turtle strandings. Further understanding how changing environmental conditions such as NAO variability and storms affect the fate of juvenile turtles is vital for understanding the distribution and population dynamics of sea turtles.

Fishers' Ecological Knowledge About Sea Turtles in Coastal Waters: A Case Study in Vengurla, India

Five species of sea turtle—the green (Chelonia mydas), hawksbill (Eretmochelys imbricata), leatherback (Dermochelys coriacea), loggerhead (Caretta caretta), and olive ridley (Lepidochelys olivacea)—feed in the coastal waters of India, nest on the mainland and island beaches, and are an important component of India's natural and sociocultural heritage. Sea turtles spend most of their life cycle at sea, so structured studies of the biology of nonnesting populations are challenging. However, fishers' ecological knowledge (FEK) could indicate sea turtle distribution, abundance, and population trends. Structured interviews with 93 male fishers at Sagareshwar Beach, Vengurla, in the Sindhudurg District of Maharashtra revealed observations of all 5 sea turtle species in local waters. Importantly, this was the first known record of loggerhead turtles for the Sindhudurg District of the state coastline and added to infrequent records of leatherback turtles over the previous 20 yrs. Observations were more common at a time when adult turtles are likely to be courting and mating, although this behavior was not observed. Fishers did not contribute ecological knowledge about sea turtle distribution from the waters they fished, potentially because of the method used to collect information on maps or reluctance to indicate areas fished. Estimates of abundance were widely disparate, but perceived decreases in the size of local populations were common among respondents. Outcomes of our study suggest that the FEK of small-scale coastal fishers operating in even a small area is of value in identifying potential areas for focused investigations on in-water populations of sea turtles.

Incorporating Geographical Scale and Multiple Environmental Factors to Delineate the Breeding Distribution of Sea Turtles

Temperature is often used to infer how climate influences wildlife distributions; yet, other parameters also contribute, separately and combined, with effects varying across geographical scales. Here, we used an unoccupied aircraft system to explore how environmental parameters affect the regional distribution of the terrestrial and marine breeding habitats of threatened loggerhead sea turtles (Caretta caretta). Surveys spanned four years and ~620 km coastline of western Greece, encompassing low (<10 nests/km) to high (100–500 nests/km) density nesting areas. We recorded 2395 tracks left by turtles on beaches and 1928 turtles occupying waters adjacent to these beaches. Variation in beach track and inwater turtle densities was explained by temperature, offshore prevailing wind, and physical marine and terrestrial factors combined. The highest beach-track densities (400 tracks/km) occurred on beaches with steep slopes and higher sand temperatures, sheltered from prevailing offshore winds. The highest inwater turtle densities (270 turtles/km) occurred over submerged sandbanks, with warmer sea temperatures associated with offshore wind. Most turtles (90%) occurred over nearshore submerged sandbanks within 10 km of beaches supporting the highest track densities, showing the strong linkage between optimal marine and terrestrial environments for breeding. Our findings demonstrate the utility of UASs in surveying marine megafauna and environmental data at large scales and the importance of integrating multiple factors in climate change models to predict species distributions.

Spatial distribution of sea turtles on South Atlantic subtropical reefs

Environmental conditions have a strong influence on sea turtle population dynamics. Sea turtles spend most of their lives in foraging areas; however, there is a lack of information on how oceanographic and biological parameters determine habitat use and density. Here, we estimated density of green turtles Chelonia mydas and hawksbill turtles Eretmochelys imbricata in a South Atlantic foraging area (Arraial do Cabo, Brazil). We also investigated the influence of environmental variables (wind fetch, temperature, depth, and visibility) and benthic composition on the distribution of turtles. Surveyed sites were split between a colder, more wave-exposed location (western), and a warmer, more sheltered location (eastern). To ensure that these mobile and sparsely distributed species were adequately surveyed, underwater visual censuses (timed transects) were conducted. Sea turtle densities were significantly different between warm/sheltered and cold/wave-exposed locations. C. mydas were almost 10 times more frequently sighted than E. imbricata. The local distribution of E. imbricata mirrored large-scale latitudinal patterns, where this tropical species is dominant on warmer reefs (similar to habitat conditions found at the eastern location). It was not possible to assess the environmental influence on E. imbricata sightings due to their low density. C. mydas were frequently sighted in the cold/exposed sites and negatively correlated with depth. Overall, the density of E. imbricata and C. mydas suggests that Arraial do Cabo is an important feeding ground in the western Atlantic Ocean. This study highlights that visual census can produce reliable density estimates of sea turtles in foraging areas.

A Systematic Review of Acoustic Telemetry as a Tool to Gain Insights Into Marine Turtle Ecology and Aid Their Conservation

While widely applied in fisheries science, acoustic telemetry remains an underutilized method in the field of marine turtle biotelemetry. However, with the ability to provide fine-scale spatial data (tens to hundreds of meters, depending on array setup and receiver range) at a low cost, acoustic telemetry presents an important tool for obtaining key information on marine turtle ecology. We present a comprehensive and systematic review acknowledging how acoustic telemetry has been used to advance the field of marine turtle ecology and conservation. We identify the extent of current studies and discuss common and novel research approaches while addressing specific limitations of acoustic telemetry. Forty-eight studies were reviewed, representing six of the seven marine turtle species and all life stages, with most individuals identified as juveniles (45%) and hatchlings (36%). Most studies (83%) focused on the spatial distribution of marine turtles, including estimating home ranges, investigating drivers of habitat use, and identifying horizontal movement patterns and vertical space use. Additionally, acoustic telemetry has been used to study hatchling dispersal and marine turtle exposure and response to threats, as well as to monitor physiological parameters. We identified that acoustic telemetry directly or indirectly informs 60% of the top questions and research priorities related to marine turtles identified by experts in the field. With an increase in acoustic telemetry receiver networks and collaborations across taxa, the applicability of acoustic telemetry is growing, not only for marine turtles but for a wide array of marine species. Although there are limitations that need to be considered at a site/project-level, acoustic telemetry is an important, low-cost technology able to address key questions related to marine turtle ecology that can aid in their conservation, and therefore should be considered by researchers as they develop their projects.

COVID-19 disruption reveals mass-tourism pressure on nearshore sea turtle distributions and access to optimal breeding habitat.

Quantifying the extent to which animals detect and respond to human presence allows us to identify pressure (disturbance) and inform conservation management objectively; however, obtaining baselines against which to compare human impact is hindered in areas where human activities are already well established. For example, Zakynthos Island (Greece, Mediterranean) receives around 850,000 visitors each summer, while supporting an important loggerhead sea turtle rookery (~300 individuals/season). The coronavirus (COVID‐19)‐driven absence of tourism in May–June 2020 provided an opportunity to evaluate the distribution dynamics of this population in the absence (2020) vs. presence (2018 and 2019) of visitors using programmed unmanned aerial system (UAS) surveys. Ambient sea temperature transitioned from suboptimal for breeding in May to optimal in late June, with turtle distribution appearing to shift from shallow (to benefit from waters 3–5°C above ambient) to deeper waters in 2018 and 2019, but not 2020. The 2020 data set demonstrated that increased tourism pressure, not temperature, drives turtles offshore. Specifically, >50% of turtles remained within 100 m of shore at densities of 25–50 visitors/km, even when sea temperature rose, with 2018 and 2019 data supporting this trend. Reduced access to warmer, nearshore waters by tourism could delay the onset of nesting and increase the length of the egg maturation period between nesting events (internesting interval) at this site. A coastal refuge zone could be delimited in May–June where touristic infrastructure is minimal, but also where turtles frequently aggregate. In conclusion, sea turtles appear capable of perceiving changes in the level of human pressure at fine spatial and temporal scales and adjusting their distribution accordingly.

Movements and distribution of hawksbill turtles in the Eastern Indian Ocean

Western Australia (WA) is one of the largest remaining hotspots for hawksbill turtles. Providing data from this region is a total of 42 satellite transmitter deployments on nesting hawksbill turtles at six rookeries (five located in WA and one in Timor-Leste) between 2000 and 2017. We used this data to quantify inter-nesting, migratory and foraging habitat use and overlap with protected areas. Turtles from WA rookeries (n = 40) remained in WA waters during their inter-nesting, migration and foraging phases, whereas those from Timor-Leste (n = 2) migrated to and foraged in WA. While inter-nesting, turtles remained in relatively small areas with an average 50% occupancy core of 39 ± 28 km2. Apart from one rookery, most of their inter-nesting distribution was contained within existing protected areas. Turtles migrating from WA rookeries remained in shallow continental-shelf waters (< 200 m), mainly following the coastline while dispersing in a north-easterly direction, whereas turtles from Timor-Leste crossed international waters. We calculated high overlap of individual turtles (56%) in a migratory corridor along the Pilbara coast, an area previously identified as critical for other migratory megafauna species. Turtles used at least 13 distinct foraging grounds, extending over ~900 km and in waters ranging from 1.5 to 84 m deep. Only 33% of this area was encompassed by either designated Biologically Important Areas for foraging hawksbill turtles (10%), or Australian and State-protected areas (23%). Unusually for this species, 17% of the turtles foraged in relatively deep waters (> 20 m), revealing new foraging habitats in need of further research and management. Our study provides the first quantitative stock-wide distribution maps for WA adult female hawksbill turtles during the different phases of their life cycle. These distributions can be used to directly refine critical areas for this species, particularly for foraging as currently only around a third of the foraging distribution we calculated overlapped with designated protected areas. It appears that Australia-focussed management strategies are appropriate for adult female hawksbill turtles from WA rookeries as they do not leave Australian waters. However, for Timor-Leste adult females, evidence of international migrations, unknown stock affiliation and limited samples sizes show that further investigation is required to understand how domestic and regional management is structured to ensure their future conservation.

Loggerhead sea turtle, Caretta caretta, presence and its exposure to floating marine litter in the Sardinia Channel and the Strait of Sicily: results from seven years of monitoring using ferry as platform of observation

The loggerhead turtle is the most common sea turtle species in the Mediterranean Sea. Despite relevant research efforts, information of its distribution is still scarce, particularly in the open sea where they may be exposed to different threats among which marine litter is of great concern. Here we investigated the distribution of loggerhead turtles and floating marine macro litter (FMML) in the Sardinia Channel and Strait of Sicily, a key area of the central Mediterranean Sea, by using 7 years of data collected by experienced observers aboard passenger ferries along commercial routes. The high-risk exposure areas were identified and the influence of upper layer currents on turtle and FMML distribution was evaluated. Overall, loggerhead sighting rates were higher than those reported from other Mediterranean routes but the distribution of turtles within the study area was clearly heterogeneous and influenced by the surface circulation pattern. Summer sighting rates were significantly higher in the Sardinia Channel with respect to the Strait of Sicily. Analysis of the co-occurrence of FMML and loggerhead turtles identified a priority risk area in the central Sardinian channel where the large South-Eastern Sardinia Gyre acts as a trap for both animals and FMML. This study corroborates the effectiveness of using passenger ferries as platforms of observation to conduct systematic surveys of sea turtles and floating macro litter in offshore areas. Results highlighted the importance of the Sardinia Channel and Strait of Sicily for the loggerhead turtle and the areas of greater risk of exposure to the marine litter threat.

Wide-Scale Population Connectivity Revealed by Postnesting Migrations of Green Sea Turtles from Ras Al Hadd, Oman

There is limited information on postnesting dispersal of green turtles Chelonia mydas from nesting sites in the Arabian region. Understanding habitat connectivity can promote effective conservation programs across a wider range of critical sea turtle habitats. We present postnesting migration data for 9 green turtles departing from Ras Al Hadd in Oman, one of the largest and most important nesting sites for this species in the northwest Indian Ocean (NWIO). Turtles migrated to Eritrea (n = 1), India (n = 2), Oman (n = 4), and the United Arab Emirates (n = 2), demonstrating connectivity for this species across the NWIO and linkages to known green turtle foraging areas. Turtles used deep international waters of the NWIO, and coastal waters of Eritrea, India, Iran, Oman, Pakistan, Saudi Arabia, and Yemen. Alongside the potential for fisheries bycatch, ghost fishing, entanglement, and direct take in waters near nesting sites and at the dispersal destinations, these movement patterns reveal a need for coordinated efforts to address sea turtle mortality in fisheries at a regional level. These data enhance our knowledge of sea turtle distribution and connectivity in the Arabian region and will contribute to ongoing efforts to conserve sea turtles in the NWIO.

A Review of Distribution of Cantor's Giant Softshell Turtle in India Along with Multiple Notable New Records from Kerala State

We review the historical and current distribution for Cantor's giant softshell turtle (Pelochelys cantorii) in India. We report 13 new records from Kerala State. Based on our intensive survey in Kasaragod District, we report a potential breeding population from this region.

Citizen-Sourced Sightings and Underwater Photography Reveal Novel Insights About Green Sea Turtle Distribution and Ecology in Southern California

East Pacific (EP) green turtles (Chelonia mydas) have undergone substantial population recovery over the last two decades owing to holistic protection at nesting beaches and foraging areas. At the northern end of their range in southern California United States, green turtles have been seen in more areas and in greater numbers since 2014 than before as a result. A resident population of green turtles has established near La Jolla Shores (LJS), a protected site with daily marine tourism (e.g., kayakers, snorkelers, divers). To study this local aggregation, innovative and non-invasive methods were required because the traditional capture-recapture methods were infeasible due to public relations sensitivities. Green turtle habituation to humans at this site has created a unique opportunity for citizen-based science using underwater photography to document turtles and their surroundings. We obtained 309 usable photographs of local green turtles from members of the dive/snorkel community in LJS. Photos were taken from April 2016 to June 2019. Images were processed in Hotspotter—a patterned species instance recognition software—to identify seven individuals, five of which were consistently photographed throughout that period. These images helped infer minimum residency duration (MRD), seasonal differences in algal coverage on the carapace, habitat association, behavioral patterns, and diet. Mean MRD was 424 days (SE = 131 days, calculated from entire population, n = 7), during which turtles were active in 82.8% of the photographs; the remainder of the photographs depicted foraging (14.9%) or resting behavior (2.3%). Green turtles were seen foraging in water temperatures as low as 15.8°C, the lowest recorded temperature for foraging green turtles documented in literature. Additional opportunistic observational platforms were used to look at trends of increasing green turtle abundance in southern California since 2015 that supported the arrival of a new aggregation of green turtles in LJS. Our use of citizen-sourced photographs confirms the presence of a resident aggregation of green turtles in LJS. Existence of green turtles and other protected species in highly populated areas provide excellent opportunities to educate beachgoers and seafarers about conservation of these species. This study also highlights the value of citizen-based science in areas where traditional research techniques are ill-suited.

Using Aerial Photogrammetry to Assess Stock-Wide Marine Turtle Nesting Distribution, Abundance and Cumulative Exposure to Industrial Activity

The lack of accurate distribution maps and reliable abundance estimates for marine species can limit the ability of managers to design scale-appropriate management measures for a stock or population. Here, we tested the utility of aerial photogrammetry for conducting large-scale surveys of nesting marine turtles at remote locations, with a focus on the flatback turtle (Natator depressus) in the Pilbara region of Western Australia. Aerial surveys were conducted between 29 November and 6 December 2016 to overlap with the peak nesting season for flatback turtles and collected imagery was used to examine marine turtle distribution, abundance, and cumulative exposure to industrial activity relative to overlap with protected areas. Two observers independently reviewed aerial georeferenced photographs of 644 beaches and recorded turtle tracks and other evidence of turtle nesting activity. A total of 375 beaches showed signs of nesting activity by either flatback, green (Chelonia mydas) or hawksbill (Eretmochelys imbricata) turtles. Most of these beaches (85.3%) were located on islands, and the rest (14.7%) on the mainland. Half (n = 174) of the active beaches showed evidence of fresh (0–36 h. old) flatback nesting activity, with track abundance varying from 1.0 to 222.0 tracks·night−1. Six rookeries accounted for 62% of the Pilbara flatback stock. Remarkably, 77% of identified flatback rookeries occurred within protected areas. However, one-third (34%) of those were also located within 5 km of a major industrial site, including eight of the highest abundance beaches (50–250 tracks·night−1). Several key rookeries were also identified as being relatively unexposed to industry-related pressures but currently unprotected, highlighting the need for a cumulative impact assessment to be completed for this flatback stock. Finally, our aerial tallies and multiple ground-survey flatback track tallies were highly correlated and together with low intra- and inter-observer errors suggested that reliable data can be collected via aerial photogrammetry for nesting marine turtles. Such large-scale digitized surveys can therefore be used to assess the cumulative exposure of marine turtles to pressures, and to reveal new conservation opportunities.

A snapshot of the distribution and demographics of freshwater turtles along Toronto’s Lake Ontario coastal wetlands

The aim of this study was to provide a baseline assessment of the turtle community in the coastal wetlands of the Greater Toronto Area. We documented turtle species diversity, abundance, reproductive classes, sex-ratios, and evidence of inter-wetland movement. Our study consisted of a series of mark-recapture surveys across eleven Lake Ontario coastal wetland complexes of the Greater Toronto Area performed between 2016 and 2019. We captured and marked 532 individual turtles of four native species (298 midland painted, Chrysemys picta marginata; 180 snapping, Chelydra serpentina; 7 Blanding’s, Emydoidea blandingii, and 5 map, Graptemys geographica) and three non-native species (40 red-eared slider, Trachemys scripta elegans; 1 false map, Graptemys pseudogeographica, and 1 Chinese softshell, Pelodiscus sinensis). Of note was the capture of an exceptionally large male snapping turtle, one of the largest recorded in Canada for both length and mass. The age classes of both snapping and midland painted species presented large proportions of breeding-sized adults, yet midland painted turtles showed a potential low recruitment with an underrepresentation of non-reproductive females. The sex ratios of both midland painted and snapping turtles across the whole waterfront did not differ from the expected 1:1 ratio. We also recaptured 198 turtles (135 midland painted, 53 snapping, 6 Blanding’s and 12 red-eared Sliders). The recaptured turtles revealed inter-wetland movements of 12 km over a two-year span for a midland painted turtle and an 8 km journey for a snapping turtle, potentially demonstrating some connectivity between geographically separate wetland complexes.

A Sea Turtle Population Assessment for Florida's Big Bend, Northeastern Gulf of Mexico

Coastal waters of Florida’s Big Bend, Gulf of Mexico (GOM) once supported one of the largest sea turtle fisheries in the United States. To fill an information gap in this region on abundance and distribution of sea turtles, we used vessel—based distance sampling and active capture methods to characterize current foraging aggregations near the St. Martins Marsh Aquatic Preserve. Over 10 sampling periods between 2012—2018, we completed 513 km of transects and recorded 819 turtles among 4 species—green turtle (Chelonia mydas, n = 624), Kemp’s ridley (Lepidochelys kempii, n = 147), loggerhead (Caretta caretta, n = 47), and a single hawksbill (Eretmochelys imbricata). Turtle densities in 4 study plots within the 200 km2 study site ranged from 57—221 immature green turtles/km2, 16—56 immature Kemp’s ridleys/km2, and 1—14 juvenile—to—adult loggerheads/km2. Of 200 green turtles captured, 67.5% showed skin tumors consistent with fibropapillomatosis, a frequency similar to that from urbanized estuaries of Florida’s east coast. The largest green turtles (&gt; 60 cm straight standard carapace length), abundant in the southern portion of our study area, are of note because this size class is uncommonly recorded within US territorial waters. Analyses of green turtle mtDNA haplotypes found contributions from rookeries in the western GOM, Mexican Caribbean, and Costa Rica. Although Big Bend protected areas were principally designed to conserve marine and coastal habitats, these regulatory zones have also effectively encompassed a hotspot for foraging sea turtles.

Ecology and Genetic Identification of Freshwater Turtles in Pakistan

Background: The turtle population plays an important role in sustaining the water ecosystem by minimizing pollution from water. The identification and molecular investigation of freshwater fauna is essential for conservation of the species that are near to extinction. The quality of water, type of flora, fauna, and environmental condition are the major factors that directly affect the distribution of freshwater turtles. Studies on the species diversity and habitat of freshwater turtle have not been focused previously in the region. The present study was the first conducted to estimate the habitat and genetic diversity of freshwater turtles using 12S rRNA (ribosomal RNA) gene in Pakistan.Materials, Methods &amp; Results: A total of 26 samples were collected from various localities using hand net, cast net, gills net, steel hooks, thick chemical wire, using chicken intestine and small fishes. The collected turtle specimens were morpho-taxonomically categorized into two genera, Lissemys punctata andersoni (n=13, 50%) and Nilssonia gangetica (n=13, 50%). The collected species showed an aggressive and active behavior in captivity during summer. Genomic DNA was extracted from collected specimens and used in PCR reaction by using specific primers for the amplification of short fragments of 12S rRNA gene. Analysis of generated sequences confirmed the existence of L. p. andersoni in the region. The generated sequences of L. p. andersoni correspond to Clad A and showed a close resemblance among different species of the genus Lissemys.Discussion: This study is the first investigation about the habitat and of the endemic turtle species L. p. andersoni and N. gangetica in Pakistan. The genetic identification followed by phylogenetic analysis based on 12S rRNA partial genes revealed a closest similarity with the sequences generated for the same species from the neighboring countries. This study provided information to conduct further molecular studies that are essential to provide significant genetic data about turtle species.Keywords: turtle, ecology, diversity, phylogeny, Pakistan.

Distribution, Abundance, and Status of Barbour's Map Turtle (Graptemys barbouri) in Florida

We collected information to determine the status of Barbour's map turtle (Graptemys barbouri) in Florida by conducting standardized surveys of occupied watersheds in 2014–2015, including the Choctawhatchee, Chipola, Apalachicola, and Ochlockonee rivers. Single-pass basking surveys were used to determine the distribution and relative abundance of G. barbouri. Multiple-pass basking surveys and N-mixture modeling were used in sections of the Apalachicola and Ochlockonee rivers to estimate detectability and abundance of map turtles. Observed counts were compared with available information from previous surveys to make inferences about population change. A total of 5917 G. barbouri observations were recorded during single-pass surveys along 502 river kilometers (rkm) and we expanded the documented range by 76 rkm. Further, we used multiple-pass surveys to estimate 2079 G. barbouri along six 2-km sections (12 km total) of the Apalachicola River (173.3 turtles/rkm) and 292 G. barbouri along five 5-km sections (25 km total) of the Ochlockonee River (11.7 turtles/rkm). The present study is the most comprehensive distributional survey for G. barbouri in Florida to date. The species was documented for the first time in 2 counties and observed counts were consistently higher than in previous surveys. Overall, the Florida population appears secure with evidence of expansion in both the Choctawhatchee and Ochlockonee drainages.

Preliminary data on an affordable UAV system to survey for freshwater turtles: advantages and disadvantages of low-cost drones

Unmanned aerial vehicles (UAVs) are established, valuable tools for wildlife surveys in marine and terrestrial environments; however, they are seldom utilized in freshwater ecosystems. Therefore, baseline data on the use of UAVs in lotic environments are needed that balances flight parameters (e.g., altitude and noise level) with image quality, while minimizing disturbance to individuals. Moreover, the traditional high-cost UAVs may present challenges to researchers conducting rapid assessments on species presence with limited funding. However, emerging, affordable UAV systems can provide this preliminary data to researchers, albeit with caveats on reliability of data. We tested a low-cost UAV system to document freshwater turtle presence, species distribution, and habitat use in a small North Carolina wetland. We observed minimal instances of turtles fleeing basking sites (∼0.7%), as this UAV system was only ∼2.1 dB above ambient noise levels at an altitude of 20 m. Freshwater turtles were found primarily in algal mat basking habitats with highly variable numbers observed across locations and flights, likely due to image quality reliability and altitude. Our affordable UAV system was successful in providing baseline information on species presence, size distribution, and habitat preference of turtles in freshwater ecosystems.

Species Distribution Modeling Provides New Insights into Different Spatial Distribution Patterns among Native and Alien Freshwater Turtles in Japan

The endemic Japanese freshwater turtle Mauremys japonica is the most common turtle in foothill areas, whereas it is usually absent or scarce in lowland environments in Japan. In contrast, another turtle, Reeves' pond turtle (M. reevesii), usually inhabits lowland areas. Explanation of this pattern based on habitat segregation between M. japonica and M. reevesii remains controversial because several studies have emphasized that M. reevesii is not indigenous but rather introduced from mainland China and the Korean Peninsula. The newly proposed hypothesis is that M. reevesii and the recently introduced red-eared slider (Trachemys scripta elegans) have excluded M. japonica from certain suitable habitats in lowland areas. In this study, to test whether M. japonica originally had a broad distribution range covering the habitats currently occupied exclusively by M. reevesii and T. s. elegans, we applied species distribution modeling using MaxEnt and ENMTools to estimate the suitable habitats and ecological niches of M. japonica, M. reevesii, and T. s. elegans, respectively, and examined these similarities. The models showed that M. japonica had the largest suitable habitat range, from flatlands to foothill areas, compared to that of alien species; however, almost the entire habitat area of the native turtle and that of the aliens overlapped. Moreover, these turtles possessed significantly high niche similarity. These results are consistent with the hypothesis that recent species interactions have shaped the distribution of indigenous and alien turtles, although the precise ecological and evolutionary processes have not yet been determined.

First record of Western Black-Bridged Leaf Turtle, Cyclemys atripons Iverson &amp;amp; McCord, 1997 (Testudines, Geoemydidae),&amp;nbsp;in Vietnam

We report the distribution of the Western Black-bridged Leaf Turtle, Cyclemys atripons Iverson &amp;amp; McCord, 1997, from Vietnam for the first time. This species was recorded on Phu Quoc Island, Kien Giang Province, southern Vietnam based on morphological and molecular evidence. This record extends the distribution of this species approximately 100 km east of the previously recorded location in Kok Kong, Cambodia. This discovery raises the recorded number of species of genus Cyclemys in Vietnam to three: C. atripons, C. oldhamii Gray, 1863, and C. pulchristriata Fritz, Gaulke &amp;amp; Lehr, 1997.