Direct and Indirect Effects of Fire on Eastern Box Turtles

Prescribed fire is an increasingly important management tool for eastern deciduous forests, but relativity little is known about the direct effects of fire on the eastern box turtle (Terrapene carolina carolina). We used very high frequency (VHF) transmitters to monitor mortality, movement, and spatial ecology of 118 box turtles in response to 17 prescribed fires across 4 seasons and 3 sites in east Tennessee, USA, during 2016–2018. Annual survival of box turtles that experienced a prescribed fire event was lower (0.87 ± 0.04 [SE]) than turtles that did not (0.98 ± 0.01) and was negatively correlated with fire intensity, fire temperature the turtle experienced, and litter depth. All prescribed fire-related mortalities occurred during the early (Apr–May, n = 5) or late growing season (Sep–Oct, n = 1). Fourteen percent of box turtles we captured exhibited damage to their carapace from previous fire events. Box turtles that survived prescribed fires were in microsites that did not burn, moved to unburned areas during the fire, or burrowed following ignition. Home range size was similar before and after burns and sinuosity of movements did not differ in burned or unburned areas. Our results indicate that though box turtles are susceptible to prescribed fire during their active season, they have behavioral and physical traits that reduce the direct effects of prescribed fire. Prescribed fire practitioners should be aware of the risks of fire, particularly during the active season. We suggest managers consider altering prescribed fire intensity, seasonality, and firing pattern to minimize risk of direct effects where box turtles are of concern. © 2020 The Wildlife Society.     

Isolation and characterization of polymorphic microsatellite loci for the three-toed box turtle (Terrapene carolina triunguis) and cross-amplification in other Terrapene species

We isolated and characterized eight polymorphic microsatellite loci for a Texas population of three-toed box turtle, Terrapene carolina triunguis, using a refined hybridization capture procedure. All eight primer pairs amplified successfully at all loci in seven Texas ornate box turtles (T. ornata ornata). Due to the decline and conservation concerns of North American box turtles, these isolated microsatellites may be a most valuable tool for evaluating baseline population genetic structure for threatened box turtle populations.     

Temporal variance in hematologic and plasma biochemical reference intervals for free-ranging eastern box turtles (Terrapene carolina carolina)

Eastern box turtle (Terrapene carolina carolina) populations are in decline, likely due to anthropogenic forces and disease, necessitating hematologic and biochemical data from healthy individuals for evaluation of wild populations. We repeatedly sampled 21 free-ranging eastern box turtles from May to September 2009 in the spring, summer, and fall to establish temporal hematologic and biochemical reference intervals. Packed cell volume, aspartate aminotransferase, and potassium levels declined significantly as the active season progressed. High levels of albumin, globulin, and calcium coincided with the presence of eggs in females. These reference intervals should provide baseline data for the clinical evaluation of wild box turtles presented for veterinary care or for studies of wild populations.     

Great Lakes coastal wetland habitat use by seven turtle species: influences of wetland type, vegetation, and abiotic conditions

Great Lakes coastal wetlands are important habitats for turtles but few studies have looked at factors driving community structure in these systems. We evaluated the effects of wetland type, vegetation, and abiotic conditions on turtle communities for 56 wetlands in Lakes Huron, Michigan, and Superior with data collected during the summers of 2000–2008. Overall, 1,366 turtles representing seven species were captured using fyke nets. For the majority of species, catches were highest in drowned river mouth wetlands In addition, turtles tended to be more abundant in water lilies, submersed aquatic vegetation, and cattails compared to bulrush. We also found positive correlations between catches of four of the species as well as total turtle catch and turtle species richness with a human disturbance gradient. These correlations suggest that turtles may be able to utilize coastal wetland areas that are inhospitable to fish because of hypoxic conditions. Our results show the importance Great Lakes coastal wetlands to turtles, and stress the need for managers to take into account turtle populations when preparing conservation and restoration strategies.     

Effects of slope, substrate, and temperature on forces associated with locomotion of the ornate box turtle, Terrapene ornata

In spite of several studies of the locomotor performances of reptiles, we know as yet relatively little about the mechanical forces involved. The present investigation examined the effects of substrate, slope and temperature on the pulling forces exerted by ornate box turtles tethered to a force transducer. These forces increased with body mass in a nearly isometric manner. The forces exerted during the initial effort were greatest on a styrofoam substrate, whereas maximum forces generated were greatest on pea gravel. Both forces progressively increased as slope decreased from +30 degrees to -30 degrees. The rate of force generation (N/s) was greatest at intermediate slopes. Contact force tended to increase as normal force increased, and was strongly influenced by slope, increasing from -30 degrees to +30 degrees. Surprisingly, we found no significant effects of temperature on tether forces, contraction times, or rates. This evaluation of pulling forces associated with box turtle locomotion revealed some interesting, and at times unexpected, relationships.     

Analysis of prey capture and food transport kinematics in two Asian box turtles,Cuora amboinensis and Cuora flavomarginata (Chelonia,Geoemydidae), with emphasis on terrestrial feeding patterns

This study examines the kinematics and morphology of the feeding apparatus of two geoemydid chelonians, the Malayan (Amboina) box turtle (Cuora amboinensis) and the yellow-margined box turtle (Cuora flavomarginata). Both species are able to feed on land as well as in water. Feeding patterns were analysed by high-speed cinematography. The main focus of the present study is on the terrestrial feeding strategies in both Asian box turtles, because feeding on land has probably evolved de novo within the ancestrally aquatic genus Cuora. During terrestrial feeding (analysed for both species), the initial food prehension is always done by the jaws, whereas intraoral food transport and pharyngeal packing actions are tongue-based. The food uptake modes in Cuoras differ considerably from those described for purely terrestrial turtles. Lingual food prehension is typical of all tortoises (Testudinidae), but is absent in C. amboinensis and C. flavomarginata. A previous study on Terrapene carolina shows that this emydid turtle protrudes the tongue during ingestion on land, but that the first contact with the food item occurs by the jaws. Both Asian box turtles investigated here have highly movable, fleshy tongues; nonetheless, the hyolingual complex remains permanently retracted during initial prey capture. In aquatic feeding (analysed for C. amboinensis only), the prey is captured by a fast forward strike of the head (ram feeding). As opposed to ingestion on land, in the underwater grasp the hyoid protracts prior to jaw opening. The head morphology of the investigated species differs. In contrast to the Malayan box turtle, C. flavomarginata exhibits a more complexly structured dorsal lingual epithelium, a considerable palatal vault, weaker jaw adductor muscles and a simplified trochlear complex. The differences in the hyolingual morphology reflect the kinematic patterns of the terrestrial feeding transport.     

Spatial Ecology and Resource Selection of Eastern Box Turtles

Eastern box turtles (Terrapene carolina carolina) are widely distributed throughout the eastern United States. Although once common throughout much of its distribution, the species has experienced declines in local populations. Understanding resource selection is important for the conservation of this species; however, few data exist on resource selection for eastern box turtles in the southeastern United States. We estimated home range and resource selection for 100 individual turtles in the Blue Ridge, Ridge and Valley, and Cumberland Plateau and Mountains physiographic regions in Tennessee, USA, from 2016 to 2018. We used step-selection functions to investigate eastern box turtle resource selection during May–August 2017 and May–August 2018 at 2 spatial scales. We classified vegetation type, measured vegetation composition and structure, recorded time since fire, and measured coarse woody debris abundance at 1,225 used telemetry locations and 1,225 associated available points. Home range sizes averaged 9.3 ha ± 3.0 (SE) using minimum convex polygon analysis, 8.25 ha ± 2.88 using 95% kernel density analysis, and 1.50 ha ± 0.56 using 50% kernel density analysis. Box turtles selected areas with greater visual obstruction at the 0–0.25-m level, greater amounts of 10-hour and 100-hour fuels (timelag categories used in fire-danger ratings), and greater litter depths compared to available locations. Box turtles were more likely to select areas with greater cover of brambles and coarser woody debris and were less likely to select areas with less vegetation cover. Vegetation type and time since last fire did not affect selection. Our data suggest that management activities that encourage greater understory vegetation cover, greater visual obstruction at the 0–0.25-m level, and greater bramble cover will enhance habitat quality for eastern box turtles. © 2020 The Wildlife Society.     

Aquatic feeding in a terrestrial turtle: a functional-morphological study of the feeding apparatus in the Indochinese box turtle Cuora galbinifrons (Testudines, Geoemydidae)

The Indochinese box turtle Cuora galbinifrons is regarded as a purely terrestrial species, but our results demonstrate that it can feed both on land and in water. The inverse relationship between the relative development of the hyoid apparatus and the tongue found in the most investigated chelonians is not valid in the Indochinese box turtle. Our morphological analysis of the feeding apparatus reveals that the palate shape and the design of the tongue are consistent with terrestrial feeders, but the construction of the hyoid complex is more characteristic of aquatic feeders. Previous studies have demonstrated that tongue enlargement negatively impacts the capacity of the turtles to suction feed. The present study focuses on the aquatic intraoral prey transport kinematic patterns. Our analysis is based on high-speed films with 250 fr/s and high-speed cineradiography with 50 fr/s. The aquatic intraoral food transport mechanisms differ depending on prey size: small items are transported predominantly by “inertial suction”, whereas larger items are moved by the tongue—normally a clear terrestrial strategy. As the genus Cuora is ancestrally aquatic, the use of lingual food transport in the aquatic environment is presumably an aberrant modus typical only for the most terrestrial among the Asian box turtles.     

Microhabitat Association of Blanding's Turtles in Natural and Constructed Wetlands in Southeastern New York

ABSTRACT We studied Blanding's turtle (Emydoidea blandingii) microhabitat in natural wetlands and wetlands constructed for the turtles in Dutchess County, New York, USA. Investigation of these topics can provide information on ways to increase the extent of Blanding's turtle habitat, improve its quality, and assure that conservation or restoration managers do not overlook key habitat characteristics. Microhabitat was determined by radiotracking individuals to their exact locations and recording habitat variables. Blanding's turtles were associated with shallow water depths (x̄ = 30 cm), muck substrates, and areas of abundant vegetation (total cover xM = 87%). Buttonbush (Cephalanthus occidentalis)had the greatest mean total cover (29%). In the constructed wetlands, Blanding's turtles were associated with significantly less cover and warmer water than in the natural wetlands. Blanding's turtles appeared to be using the constructed wetlands to bask and forage in the spring and early summer but moved to deeper wetlands in late summer when the constructed wetlands dried up or became too warm. For Blanding's turtles, new habitat should contain abundant emergent vegetation (including buttonbush in Dutchess County and other areas where the turtles are known to use buttonbush swamps), basking areas, muck, floating plant material, and submerged aquatic vegetation. Blanding's turtle's use of constructed wetlands highlights the value of a complex of connected wetland habitats in providing for the varied needs of the turtle.     

Modifications of traps to reduce bycatch of freshwater turtles

Mortality of freshwater turtles varies among types and deployments of traps. There are few or no losses in hoop or fyke traps set where turtles may reach air, including placement in shallows, addition of floats on traps, and tying traps securely to a stake or to shore. Turtle mortality occurs when traps are set deep, traps are checked at intervals >1 day, and when turtles are captured as bycatch. Devices are available that exclude turtles from traps set for crab or game fish harvest. Slotted gates in front of the trap mouth reduce turtle entry, but small individuals still may be trapped. Incidental take of turtles is preventable by integrating several designs into aquatic traps, such as adding floats to the top of traps so turtles may reach air or an extension tube (chimney, ramp) that creates an escape route. © 2010 The Wildlife Society.     

Microclimates and energetics of free-living box turtles, Terrapene carolina, in South Carolina

We measured microclimate, field metabolic rates (FMRs), water flux, and activity patterns of telemetered box turtles (Terrapene carolina) in South Carolina from September 1987 to October 1988. Turtles were inactive for most of the winter and were active only sporadically during the rest of the year. Using the doubly labeled water method, we found that water flux averaged 8.8, 18.9, and 26.4 mL kg(-1) d(-1) in winter, spring, and summer/fall, respectively. FMR for the same periods averaged 0.028, 0.065, and 0.124 mL CO(2) g(-1) h(-1). Differences in FMR among seasons were significant but not between sexes. Using operative temperatures, we predicted standard and maximum metabolic rates of turtles. In winter, FMR was elevated above standard metabolic rates and close to maximum metabolic rates, whereas in spring and summer/fall, FMR fell midway between standard and maximum metabolic rates. We used a model to predict metabolic rates, geographical distribution, and potential reproductive output of box turtles across latitudes in eastern North America. Low FMR and low annual reproductive output may allow box turtles to survive and flourish in unpredictable resource environments by minimizing costs and risks, thereby maintaining greater lifetime reproductive success.     

Past, current and future thermal profiles of green turtle nesting grounds: Implications from climate change

Sex determination and hatching success in sea turtles is temperature dependent and as a result global warming poses a threat to sea turtles. Warmer sand temperatures may skew sea turtle population′s sex ratios towards predominantly females and decrease hatching success. Therefore, understanding the rates at which sand temperatures are likely to increase as climate change progresses is warranted. We recorded sand temperature and used historical sea surface and air temperature to model past and to predict future sand temperature under various scenarios of global warming at key sea turtle nesting grounds (n = 7) used by the northern Great Barrier Reef (nGBR) green turtle, Chelonia mydas, population. Reconstructed temperatures from 1990 to the present suggest that sand temperatures at the nesting sites studied have not changed significantly during the last 18 years. Current thermal profile at the nesting grounds suggests a bias towards female hatchling production into this population. Inter-beach thermal variance was observed at some nesting grounds with open areas in the sand dune at northern facing beaches having the warmest incubating environments. Our model projections suggest that a near complete feminization of hatchling output into this population will occur by 2070 under an extreme scenario of climate change (A1T emission scenario). Importantly, we found that some nesting grounds will still produce male hatchlings, under the most extreme scenario of climate change, this finding differs from predictions for other locations. Information from this study provides a better understanding of possible future changes in hatching success and sex ratios at each site and identifies important male producing regions. This allowed us to suggest strategies that can be used at a local scale to offset some of the impacts of warmer incubating temperatures to sea turtles.     

Thermoconformity strategy in the freshwater turtle Hydromedusa tectifera (Testudines,Chelidae) in its southern distribution area

Ectotherm species are not capable of generating metabolic heat; therefore, they present different strategies for regulating their body temperatures, ranging from a precise degree of thermoregulation to a passive thermoconformity with ambient temperatures. In reptiles, aerial basking is the most common mechanism for gaining heat. However, among aquatic reptiles, such as freshwater turtles, aquatic basking is also frequent. Hydromedusa tectifera is a turtle of exclusively aquatic and nocturnal habits widely distributed in South America. We studied the relationship between body temperature (Tb) of H. tectifera and its habitat, and explored the effects of sex, life stage and body size and mass on Tb. Fieldwork was conducted in two streams of a mountain area of central Argentina. We recorded cloacal temperature, size and mass of 84 turtles. We also determined individuals’ sex and life stage (adult/juvenile). Regarding ambient temperatures, we measured water temperature on the surface (Tsurf) and at depth of turtle capture (Tdepth) and air temperature. Mean Tb was 18.58 °C (Min = 10.20 °C; Max = 25.70 °C). Tsurf and Tdepth were highly correlated. Multi-model analysis using Akaike criterion indicated that Tb was strongly associated with water temperature, whereas air temperature and body size and mass did not show a significant effect. There was also no effect of turtle sex or life stage on Tb. Our results indicate that H. tectifera is a thermoconformer and eurythermal species. A nocturnal pattern of activity and a fully aquatic lifestyle are suggested as determinant factors.     

Seasonal fire effects on the diversity patterns,spatial distribution and community structure of forbs in the Northern Mixed Prairie,USA

The effects of fire season on forb diversity patterns, density, and composition were determined for a northern Mixed Prairie site, USA. Repeated spring burns (dormant season), summer burns, fall burns (dormant season), and unburned treatments were compared over a 3-yr period characterized by wet and dry moisture conditions. Alpha and beta diversity were highest on unburned and summer burn treatments, while landscape mosaic diversity was highest on fall burns. Forb density was highest on fall and spring burn sites. Nine forb species comprised 82% of total densities and were significantly affected by fire season and year to year variations in moisture. Forb composition for unburned and spring burn treatments was similar, but both treatments were different from the summer burn and fall burn treatments which were similar to each other. Fire alone did not appear to be an intense enough disturbance to initiate drastic changes in the forb component of vegetation patches. Specific fire seasons did appear to either mask or enhance forb structure arising from other disturbance(s). Fire season also affected the scales of forb organization in the landscape. Contrasting spatial characteristics of the forb component of prairie plant communities may provide a diagnostic technique for exposing the interaction of disturbances at different temporal and spatial scales.     

Hibernal thermal ecology of eastern box turtles within a managed forest landscape

Box turtles are being extirpated from much of their former range and remaining populations often live in association with anthropogenically altered habitats. This is particularly evident at the northern distributional limit of eastern box turtles (Terrapene carolina carolina) and is an important factor to consider during the winter months when their ability to respond to microclimatic change is limited. Using temperature dataloggers, we studied the hibernal microclimate of box turtles and associated habitat following timber harvests. We monitored the body temperatures of 38 eastern box turtles and collected detailed air and soil profile temperatures of 12 box turtle hibernacula, 6 clearcuts, and 6 adjacent forested areas during the hibernal season (winter 2009–2010). We partitioned the hibernal season into 2 biologically significant thermal periods: hibernation and emergence. The mean hibernation body temperature averaged (3.28° C, SE = 0.09) and corresponded to an average depth of 10 cm. Clearcuts were consistently colder ( = 1.91° C) than forests ( = 2.68° C) and hibernacula ( = 2.77° C) during hibernation, but became the warmest areas during emergence ( = 9.96° C). We found that in the average clearcut, turtles could burrow to approximately 20 cm to attain the average hibernation body temperature or to approximately 15 cm to attain a body temperature no different than those overwintering on colder, northeast-facing slopes in the forest ( = 2.83° C). Alternatively, we found that southwest-facing slopes were warmer and if turtles chose to overwinter only in clearcuts on those slopes, they could remain shallower. All but 1 turtle overwintered in forested areas; however, our study suggests that some timber harvested areas offer various microhabitats exploitable by hibernating box turtles based on soil profile temperatures, slope aspect, and depth of hibernation. © 2012 The Wildlife Society.     

Long-term monitoring of leatherback turtle diving behaviour during oceanic movements

The diving behaviour of four leatherback turtles (Dermochelys coriacea) was recorded for periods of 0.5-8.1 months during their postnesting movements in the Indian and Atlantic Oceans, when they covered 1569-18,994 km. Dive data were obtained using satellite-linked transmitters which also provided information on the dive depths and profiles of the turtles. Turtles mainly dove to depths < 200 m, with maximum dive durations under 30-40 min and exhibited diel variations in their diving activity for most part of the routes, with dives being usually longer at night. Diurnal dives were in general quite short, but cases of very deep (> 900 m) and prolonged (> 70 min) dives were however recorded only during daytime. The three turtles that were tracked for the longest time showed a marked change in behaviour during the tracking, decreasing their dive durations and ceasing to dive deeply. Moreover, diel variations disappeared, with nocturnal dives becoming short and numerous. This change in turtle diving activity appeared to be related to water temperature, suggesting an influence of seasonal prey availability on their diving behaviour. The turtle diving activity was independent on the shape of their routes, with no changes between linear movements in the core of main currents or looping segments in presence of oceanic eddies.     

Coexistence of <Emphasis Type="Italic">Placobdella costata</Emphasis> (Fr. Müller, 1846) (Hirudinida: Glossiphoniidae) and mud turtle <Emphasis Type="Italic">Emys orbicularis</Emphasis>

Emys orbicularis is receding from Europe, mainly due to anthropogenic habitat changes. Its parasite, Placobdella costata, is widely distributed within both the former and the present distribution range of the host. Though closely associated with the mud turtle, it may have other hosts (birds, amphibians, reptiles). Its reproductive period coincides with that of its host’s migration to the breeding grounds, thus facilitating dispersal of the parasite. Based on literature data we have analyzed the geographic spread of P. costata and mud turtle to observe the possible overlap of their habitats. Observations on the population of mud turtle and the associated leech species (P. costata) were carried out in eastern Poland — Podlasie Lowland. The studies were conducted in spring and summer in 1986–1993. The leeches were collected from the turtles caught in the water and on land. Observations showed that most leeches were found on turtles inhabiting the lake or moving to a breeding area. The greatest intensity of invasion was observed in June and July and that most leeches were observed in female E. orbicularis characterized by greater length of the carapace and weight, compared with males and juvenile individuals.     

First Assessment of the Sex Ratio for an East Pacific Green Sea Turtle Foraging Aggregation: Validation and Application of a Testosterone ELISA

Determining sex ratios of endangered populations is important for wildlife management, particularly species subject to sex-specific threats or that exhibit temperature-dependent sex determination. Sea turtle sex is determined by incubation temperature and individuals lack external sex-based traits until sexual maturity. Previous research utilized serum/plasma testosterone radioimmunoassays (RIA) to determine sex in immature/juvenile sea turtles. However, there has been a growing application of enzyme-linked immunosorbent assay (ELISA) for wildlife endocrinology studies, but no study on sea turtles has compared the results of ELISA and RIA. This study provides the first sex ratio for a threatened East Pacific green sea turtle (Chelonia mydas) foraging aggregation, a critical step for future management of this species. Here, we validate a testosterone ELISA and compare results between RIA and ELISA of duplicate samples. The ELISA demonstrated excellent correspondence with the RIA for providing testosterone concentrations for sex determination. Neither assay proved reliable for predicting the sex of reproductively active females with increased testosterone production. We then applied ELISA to examine the sex ratio of 69 green turtles foraging in San Diego Bay, California. Of 45 immature turtles sampled, sex could not be determined for three turtles because testosterone concentrations fell between the ranges for either sex (females: 4.1–113.1 pg/mL, males: 198.4–2,613.0 pg/mL) and these turtles were not subsequently recaptured to enable sex determination; using a Bayesian model to predict probabilities of turtle sex we predicted all three ‘unknowns’ were female (> 0.86). Additionally, the model assigned all turtles with their correct sex (if determined at recapture) with 100% accuracy. Results indicated a female bias (2.83F:1M) among all turtles in the aggregation; when focusing only on putative immature turtles the sex ratio was 3.5F:1M. With appropriate validation, ELISA sexing could be applied to other sea turtle species, and serve as a crucial conservation tool.     

Erfahrungsbericht über die Haltung und deutsche Erstzucht der Borneo-Flussschildkröte (Orlitia borneensis Gray, 1873) im Zoo Dresden

Dresden Zoo bred successfully the Malaysian giant turtle (Orlitia borneensis) in summer 2012. This was the first successful breeding of this species in Germany.Little is known about biology and behaviour of this large river turtle and keeping and especially breeding of this endangered species in captivity is a rarity. In order to create optimal breeding conditions Dresden Zoo rebuilt an enclosure for the turtles in 2010. An area with soil and sand was built for the expected egg deposition. After arranged matings one female dug a nest on this area and buried her eggs. Nine eggs were secured and transferred into an incubator in a box filled with a 1:1 mixture of vermiculite and water. The average temperature was 29 °C. After problems with the temperature regulation the damaged incubator had to be replaced. Because of an estimated incubation period of 3–4 months, one egg was opened on day 127 of incubation. A live hatchling with a big yolk sac was fetched. Because of the non-reabsorbed yolk sac the hatchling was further incubated. On day 154 of incubation all eggs were manually opened and the hatchlings were fetched. All of these hatchlings showed a non-reabsorbed yolk sac and were incubated onwards in a box with wet paper towel until the yolk sac was completely reabsorbed. After that the hatchlings were housed solitarily in a box with water of approximately 4 cm height and a small land area. Two days after housing food was offered for the first time. All hatchlings accepted the offered food consisting of herbal as well as of animal products and later turtle pellets and self-made turtle jelly.Though little is known about breeding this species, the breeding success of Dresden Zoo demonstrates a possible approach to this topic. But there are still things to optimize. For example the manual hatching is something that should be avoided in future. Fertilization and hatching rate of 100% are promising and up to date eight out of nine hatchlings are still alive.