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Northeastern Naturalist publishes natural history research related to the biology and ecology of the organisms and environments of northeastern North America.
For species of conservation concern, documenting extant populations is a critical first step to making informed conservation and management decisions at both local and regional scales. We implemented a standardized survey protocol, consisting of both trapping and visual-encounter surveys, in an effort to document Clemmys guttata (Spotted Turtle) populations at sites across Florida, Georgia, and South Carolina from 2018 to 2021. We surveyed a total of 56 sites, conducting 5703 trap nights and 891 visual-encounter surveys. Across all surveys, we observed Spotted Turtles at 16 sites, including 5 long-term–monitoring sites and 11 sites that were formally surveyed for the first time. Of the 11 new sites with detections, 7 were characterized by the observation of just a single individual. Using single-season occupancy models, we found that estimates of occupancy (min–max: 0.12–0.13) and detection (min–max: 0.19–0.20) probability were low at mean covariate values. Overall, we struggled to document Spotted Turtle populations across 3 southeastern states using standardized survey methodologies. Even successful documentation of new populations was often supported by few individuals, suggesting our survey efforts were missing core-activity areas, that populations exist at low densities, and/or that populations have declined at some sites.
Understanding space-use dynamics of wildlife populations is important for informing habitat management and restoration initiatives. In West Virginia, Clemmys guttata (Spotted Turtle) is restricted to the eastern panhandle region and is considered a species of greatest conservation need. The West Virginia Division of Natural Resources is interested in managing and restoring Spotted Turtle habitat, but information on space use is limited. To address this information gap, we used radiotelemetry to track space-use patterns of 9 Spotted Turtles at 2 sites that represent different wetland types in the state from spring 2018 to fall 2020. One site was a wetland complex containing ∼13.19 ha of potential habitat, and the other site was a single isolated wetland containing ∼2.09 ha of potential habitat. Spotted Turtle home-range size and use of potential habitat varied between the sites, with larger home-range sizes and a larger proportion of habitat used at the wetland complex site. Our results represent the first home-range size estimates reported for Spotted Turtle populations in West Virginia and suggest that space-use dynamics may be variable and dependent on site-level wetland characteristics.
In temperate climates, freshwater turtles have to contend with the challenges of hypoxic or anoxic conditions that prevail in ice-covered wetlands during the winter months. Here we describe behavior indicating that Clemmys guttata (Spotted Turtle) make small adjustments to their position late in the overwintering period. We speculate that these movements facilitate access to higher concentrations of dissolved oxygen near the water's surface, and also to the first available aerial oxygen once ice-cover has melted. This access to oxygen in early spring would help eliminate the consequences of acidosis generated over the winter when long-term hypoxia forces turtles to respire using anaerobic pathways.
Predation can lead to nonlethal injury as well as mortality in turtles, with many Clemmys guttata (Spotted Turtle) having predator-induced limb and foot amputations. The impact of such injuries on movements of freshwater turtles remains poorly understood. We tracked Spotted Turtles (n = 20) in a single population on the Delmarva Peninsula using radio telemetry for ∼1 year. Seven turtles had at least 1 limb or foot completely amputated by a predator, and the remaining 13 were uninjured. When comparing movements among turtles, we found no difference in home-range sizes between male (n = 8) and female (n = 7) nor between injured (n = 7) and uninjured (n = 8) Spotted Turtles during their breeding season. However, injured turtles (n = 5) had smaller home ranges (mean ± SE = 0.26 ± 0.14 ha) than uninjured turtles (n = 12, 0.74 ± 0.15 ha) during the nonbreeding season, when turtles are more terrestrial. Our findings suggest a potential ecological cost of nonlethal injury, as predator effects might extend beyond simple mortality.
The last description of the abundance and distribution of Clemmys guttata (Spotted Turtle) on the island of Martha's Vineyard, MA, was published in 1976 by James Lazell. From 2020 to 2022, we surveyed wetlands with historic records or verified sightings of Spotted Turtles. We captured and marked 24 individuals in 1362 trap nights (0.018 spotted turtles/trap night). We identified 3 Spotted Turtle populations with 5–13 individuals, but only 1 population exhibited a variety of age and size classes among captures. Lazell noted this turtle species was uncommon in the 1970s, and our surveys indicate they may be even less common today, as we found the species at only 2 of the 4 sites Lazell surveyed. Considerable development and habitat fragmentation have degraded the landscape surrounding wetlands across the island in the last 30 years and sea-level rise threatens 2 populations, putting this elusive turtle at risk of local extinction.
We studied an offshore population of Clemmys guttata (Spotted Turtle) on a morainal island in Dukes County, MA, that served as a US Navy range from 1943 to 1996. We established a permanent study area consisting of 3 distinct wetland basins encompassing 2.11 ha (5.21 ac) of emergent marshes and ponds, including ∼4.3 % of all National Wetlands Inventory-classified palustrine wetlands on the island. Within our study area, we estimated the average population size of adult turtles to be 110.1 adult turtles during 2019–2021, or a density of 52.2 turtles/ha of wetland. Among the wetlands in our study area was a 1.1-ha (2.7-ac) emergent marsh 19 m (62 ft) in elevation that had breached into the ocean immediately prior to our study as the result of coastal erosion. Twenty-two adult turtles (28%) exhibited deformed or missing limbs, despite an absence of mammalian predators. The morainal islands of southern New England appear to be vulnerable to coastal erosion that can affect freshwater wetlands more than a dozen meters above sea level. Future work at this island should evaluate the response of Spotted Turtles—at the individual and population level—to ongoing coastal erosion, and the proximate causes of limb deformity.
Natural wildfire regimes are important for ecosystem succession, but increased frequency and severity of wildfire due to climate change can negatively alter habitat characteristics. In 2018, over 11,000 ha of a granite rock barrens landscape that extends along the eastern shoreline of Georgian Bay, Lake Huron, burned in a wildfire. This landscape is a biodiversity hotspot providing habitat for many species at risk, including Emydoidea blandingii (Blanding's Turtle) and Clemmys guttata (Spotted Turtle), where turtles nest in shallow soil deposits in cracks and crevices in the bedrock. The burned, open rock-barren habitat had ∼70% fewer available nesting sites, but suitability of remaining nest habitat was unknown. To assess the impact of the wildfire on the suitability of turtle nesting habitat, we compared soil properties and in situ thermal and moisture regimes at turtle-selected nest sites, burned and unburned rock barren habitat, and burned forested uplands that may provide newly available habitat as a result of increased canopy openness following fire. Burned and unburned rock barren habitats drained quickly following rainfall, similar to turtle-selected sites, whereas burned forested uplands drained more slowly and provided wetter incubation conditions. Burned forested uplands provided a comparable thermal regime to turtle-selected nest sites and were often moss-dominated, with a relatively open canopy. Hatch success was estimated to be 20% lower at burned rock-barren habitats compared to unburned sites. Our findings suggest that severe wildfire affects soil thermal and moisture regimes, which can negatively alter the suitability of nest habitat, but burned upland forests are likely to provide suitable nesting habitat for at-risk turtles in the first years following fire.
A regionally significant population of the rare Emydoidea blandingii (Blanding's Turtle) at Great Meadows National Wildlife Refuge (GM) in Massachusetts declined in numbers of individuals of >110 mm SCL from an estimated 135 in 1973 to ∼54 in 2004, when we began a long-term conservation management program for this population. In the early years of our efforts, the majority of females in the population were older individuals, mostly marked as adults in the 1970s (and thus >50 years old), and juveniles appeared scarce. In response, we began protecting Blanding's Turtle nests at GM in 2003 and began headstarting hatchlings and releasing them back into the population regularly in 2007. By the end of 2023, we had released 683 headstarted juveniles into the GM wetlands. Using data from nearly 20 years of population monitoring, including 430 turtle-years of radiotelemetry, we estimate that the number of Blanding's Turtles >110 mm SCL at GM has increased significantly during that period. Our 2023 population estimates, derived from an integrated capture–recapture model (using trapping and telemetry data) and a known-fate model (telemetry only) suggest that the population has nearly quadrupled (204 individuals, 95% CI = 176–240) or sextupled (316 individuals, 95% CI = 185–442), respectively, when compared to the 2003 estimate (54 individuals). Trapping data also support the conclusion that headstarting has greatly augmented the GM Blanding's Turtle population, with the population skewing younger and catch-per-unit-effort climbing throughout this effort.
Headstarting is an increasingly common tool used by conservationists, especially with herpetofauna. However, attaining meaningful conservation results often entails headstarting large numbers of animals over many years, a significant investment of time, resources, and space. In order to share the burden of the work, and also enable community engagement in the project, we partner with local schools to raise the turtles in classrooms. Headstarting in schools also allows us to expose participating school children to local conservation concerns and give them an opportunity to make a difference in their communities. At the same time, a decentralized headstarting structure can present challenges, such as ensuring that protocols and standards are maintained, communicating with a large group of caretakers, and monitoring the health and growth of animals in different locations. Based on 14 year's experience in overseeing the raising of nearly 1000 hatchling Emydoidea blandingii (Blanding's Turtle) and Glyptemys insculpta (Wood Turtle) in classrooms, we present our key lessons learned and best practices for other organizations who may be contemplating similar collaborations with local schools.
Researchers have observed sexual dichromatism in chelonians, but it has not been formally documented in Emydoidea blandingii (Blanding's Turtle). We tested if this characteristic can be detected in the upper tomium coloration and pattern of Blanding's Turtles, and if so, how accurately sex can be determined using this characteristic. We sorted individuals based on non-color traits to confirm the presence of sexual dichromatism. We created the following sexual dichromatism guideline: males have dark upper tomia, and females have cream/yellow tomia with black banding. Thirteen observers categorized 179 tomium photographs to assess the guideline accuracy. Observers correctly identified the turtle's sex 96.78% of the time. The guideline can be a useful tool for determining sex in the field and has beneficial conservation applications.
Jared M. Green, Stephanie L. Koch, Kurt A. Buhlmann, Brian A. Bastarache, Kourtnie A. Bouley, Brian O. Butler, Richard B. Chandler, Tracey D. Tuberville
Emydoidea blandingii(Blanding's Turtle) is a species facing a variety of anthropogenic threats that decrease population viability. We initiated a project to establish a new population of Blanding's Turtles on a National Wildlife Refuge in Massachusetts using hatchlings obtained from a nearby, robust donor population. We released 440 headstarted individuals and 401 directly released hatchlings between 2007 and 2013 and conducted multiple years of post-release monitoring via aquatic trapping to estimate survival. Between 2014 and 2021, we released an additional 824 headstarted and 433 directly released individuals and conducted 1 year of aquatic trapping in 2021 to estimate population size. First year post-release survival of headstarted turtles was 6 times that of directly released hatchlings (0.72 vs. 0.12, respectively), but annual survival of both groups was 0.78–0.90 in subsequent years. Only 19% of turtles released at <60 mm carapace length (CL) were subsequently recaptured compared to 60% of those released at ≥60 mm CL, supporting 60 mm CL as a target minimum release size. The mean population estimates using 2 different study designs were 164 and 202, with 91 individuals encountered. Now that turtles released early in the project are approaching reproductive maturity, we recommend resampling and expanding trapping efforts to include more wetlands to assess long-term survival, abundance, and distribution of Blanding's Turtles in this newly established population. Our results, combined with other evaluations of headstarting across the species' range, add credence to the use of headstarting as a population-recovery tool for Blanding's Turtles.
We studied the spatial ecology of globally endangered Emydoidea blandingii (Blanding's Turtle) inhabiting a wetland in the urban center of Sudbury, ON, Canada. Between May 2013 and October 2014, we captured 12 individuals, 6 of which were radio-tagged and tracked. We found that home-range sizes (minimum convex polygon: mean = 32.9 ha) and minimum daily movements (mean = 47.5 m/day) were similar to those reported in the literature for conspecific turtles in more pristine habitats. However, we found that turtles displayed strong selection for specific habitat types including drainage channels, indicating that urbanization may have influenced habitat selection. In 2019, when we conducted follow-up surveys, we captured 1 new adult turtle, and found 1 previously captured turtle outside of its former home range, highlighting the importance of long-term studies to support effective conservation of endangered species in challenging urban landscapes.
While conducting research on urban ecology of turtles, I recorded probable nesting by Emydoidea blandingii (Blanding's Turtle) on high rocky outcrops on the Canadian Shield in Greater Sudbury, ON, Canada. While the use of rocky outcrops for nesting by this species has been well-documented, the elevation of nesting sites relative to wetland of origin are under-reported. Here I report on 2 nest sites within an anthropogenically impacted landscape, 44 m (144 ft) and 50 m (164 ft) in elevation above the wetland of origin. I also report on an instance of a depredated nesting female.
We studied Actinemys pallida (Southwestern Pond Turtle) in Amargosa Creek, near Palmdale, CA, from 1997 to 2023. The population in the upper creek was the focus of a mark–recapture study from 1997 to 2003 during monitoring required by a road-construction project. An estimated 193 (95% CI = 142–256) turtles were present in 1997 or recruited to the upper creek population between 1997 and 2003. Total abundance and recruitment declined after 2001, coincident with the onset of a multi-decadal megadrought. Turtles in upper Amargosa Creek are presumed to be extirpated because the creek dried up in the ensuing years. As part of a separate research project, we resurveyed the lower creek at Piute Ponds on Edwards Air Force Base from 2019 to 2023. As of 2023, there was a remnant breeding population of at least 22 turtles there. We did not find any marked turtles from the upper creek in the ponds. Only 2 populations of Southwestern Pond Turtles are known to survive in the Mojave Desert, one at Piute Ponds and another in the Mojave River.
Mark A. Jordan, Brendan N. Reid, Daniel J. Guinto, Whitney J.B. Anthonysamy, Christina M. Davy, Judith Rhymer, Michael Marchand, Matthew Cross, Gregory Lipps Jr, Yu Man Lee, Bruce Kingsbury, Lisabeth Willey, Michael Jones, Jonathan Mays, Glenn Johnson, Lori Erb
Adequate genetic variation in a population is fundamental to reducing the risk of inbreeding depression in the short term and maintaining its ability to respond to evolutionary forces over the long term. There are now several studies that use microsatellite loci to assess genetic variation within populations across the geographic range of Emydoidea blandingii (Blanding's Turtle), but direct comparisons among studies have not been conducted. We present estimates of allelic richness (A) and expected heterozygosity (HE) from 59 localities across much of the species'geographic range and compare them using a resampling method that calibrates values relative to a reference population to account for different sample sizes and microsatellite panels. We further compared these measures between 2 datasets, from the midwestern US and from the northeastern US, that were made compatible using a sample of re-genotyped individuals. In both cases, we found lower A and HE in the northeastern localities. We also developed a sensitivity analysis of effective population size (Ne) estimation with the linkage disequilibrium method (NeLD) that used a well-sampled population modelled in the program ‘NeOGen’ to explore the effects of adult population size (Nc), sample size, and locus number while accounting for overlapping generations, life history, and demography. We find that it is possible to estimate Ne with accuracy and precision in populations with Nc < 400 when sample size is ∼25% of adult population size and ≥11 microsatellite loci are used. With this benchmark, we then estimated NeLD in 7 localities using single-sample linkage disequilibrium in NeEstimator, a method that does not account for overlapping generations, demography, and life history but is more accessible for users. This approach overestimated NeLD by ∼37%. Collectively, our analyses of genetic variation within populations facilitate assessment of population status and resiliency in Blanding's Turtles by demonstrating the range of genetic variation across a large number of populations and developing a baseline for the estimation of effective population size in natural populations.
We studied a remote and robust population of Actinemys pallida (Southwestern Pond Turtle) in the upper Río Santo Domingo (RSD) watershed, Sierra San Pedro Mártir, Baja California, Mexico. We conducted cursory assessments in 2014 and 2015 and intensive trap-based surveys in 2016 and 2022. We captured and marked 486 unique turtles a total of 597 times. Using closed-population models within years, we estimated the total abundance of one 3.8-km study reach to be 511.1 (CI = 395.7–686.5) turtles in 2016 and 663.8 (467.2–1011.0) turtles in 2022, equivalent to instream densities of 134.5 turtles/river-kilometer (rkm) in 2016 and 174.7 turtles/rkm in 2022. The proportion of juveniles among detected turtles was 0% in 2014, 4.6% in 2015, 21.7% in 2016 and 19.6% in 2022. In 73.5 trap-nights (TN), we recorded 532 captures, equivalent to an average of 7.24 turtles/TN or 0.30 turtles/trap-hour. The RSD population appears to be one of the largest known in Baja California and is relatively large across the range of the Southwestern Pond Turtle. Thirty-three turtles recaptured more than 1 year apart had moved up to 1.6 km downstream and 2.3 km upstream, averaging a net upstream movement of 240 m. Adult males and females both had an average straight carapace length (SCL) of 112 mm, which is small for Southwestern Pond Turtles, but expected in the regional context. In addition to a regionally significant population of Southwestern Pond Turtles, this isolated, perennial watercourse supports a micro-endemic fish and 2 regionally rare amphibians and warrants protection as a globally significant biodiversity reserve.
Based on a long-term dataset, this paper is part of a series exploring the influence of environmental spatial and temporal heterogeneity on reproduction, recruitment, survival, and movement of Emydoidea blandingii (Blanding's Turtle) in Nova Scotia, at the northeastern limit of the species' range. This population complex comprises 4 geographically discrete and genetically distinguishable subpopulations that vary in morphology, reproduction, and behavior. This variation may reflect different local environments and evolutionary histories and underscores the importance of understanding ecological scale(s) to ensure that we adopt appropriate management scale(s) for this endangered population. Here we compare clutch size, nesting frequency, dates of nesting and emergence, incubation period, hatching success, and recruitment over 20 years of nest monitoring and protection between 3 of the 4 subpopulations. While nesting frequency was similar across all 3, dates of nesting and emergence, incubation period, and hatching success varied. Clutch size varied with both body size and subpopulation. Despite considerable interannual variation, average dates of nesting and emergence in the 3 subpopulations over the 20-year period were ∼6–10 days earlier and ∼12–18 days earlier, respectively, consistent with a climate change-induced signal.
Water depth may be a primary factor that influences aquatic habitat use by Glyptemys insculpta (Wood Turtle). We used radio telemetry to investigate the influence of sex and activity period on water depth used by Wood Turtles to reveal aquatic behavioral patterns with potential habitat-management implications for this imperiled species. We located 42 Wood Turtles (28 females, 14 males) from 3 sites in Iowa biweekly to bimonthly during 2017–2021. We measured water depth at 1784 individual turtle locations and compared turtle depth to the minimum and maximum depths within 10 m of the turtle, and stream depth at mid-channel, to determine if water depth differed between sexes and/ or 5 seasonal activity periods (brumation, pre-nesting, nesting, post-nesting, and pre-brumation). Activity period significantly affected water depth used, and both sexes chose deeper water locations during winter brumation (mean = 110.6 cm) than during the other 4 activity periods. However, sex, and the interaction between sex and activity period, were not significant factors. Both sexes utilized deep water (81–121 cm) most frequently (35.6% of observations) during brumation. Utilization of moderately deep, flowing-water areas during winter may be an adaptation in Wood Turtles that provides protection from thickening river ice and fluctuating water levels while they are largely inactive. Our results provide data that can be used by habitat managers to mitigate the effects of various bridge, roadway, and stream-based construction projects that may influence stream depth and water flow in Wood Turtle habitat.
Massachusetts populations of Glyptemys muhlenbergii (Bog Turtle) encompass the northeasternmost limit of the species' range. Populations of this species have declined primarily as a result of habitat alterations and fragmentation. We report hepatic neoplasia in 2 adult Bog Turtles from the same fen in Massachusetts in the spring and summer of 2020. The presence of neoplasia in 2 turtles from the same site is notable and has potential conservation implications for disease surveillance and research, population monitoring, and threats assessment of this critically endangered species that often occurs in small, isolated populations.
Wisconsin encompasses a substantial portion of the Upper Midwest distribution for the globally endangered Glyptemys insculpta (Wood Turtle). However, the paucity of prior research and population monitoring statewide has limited our understanding of their status and population trends in the state. To address this information gap, we conducted standardized Wood Turtle population surveys at 50 sites across 8 HUC-8 watersheds in Wisconsin from 2018 to 2023 to estimate adult abundance and population demographic parameters. We captured turtles at 29 of 50 sites, and detected 250 unique individuals, consisting of 107 adult females, 77 adult males, and 66 juveniles. Site-level estimated adult abundances varied from 0 to 23 (mean = 5 among all sites surveyed). Our results provide a foundation for assessing long-term population trends and responses to conservation and habitat management efforts for Wood Turtles in Wisconsin.
Increased mortality of freshwater turtles due to changing climate conditions, possibly due to increased predation because of a lack of refugia in drought years, is a key issue facing turtle-recovery efforts. Zoo New England's Field Conservation department has been studying and protecting Glyptemys insculpta (Wood Turtle) in Massachusetts since 2012 and has been headstarting juvenile turtles and tracking adult and headstart survival intensively since 2019. Following several anecdotal observations that Wood Turtle mortality was disproportionately high during drought years across several study sites, we analyzed data from a multi-year survey of 112 unique individual Wood Turtles living in eastern Massachusetts. We found via one-way ANOVA that lower mean stream depth was a significant predictor of Wood Turtle mortality (P = 0.037) and that a generalized linear model using stream depth as a predictor of Wood Turtle survival had more explanatory power than models using rainfall, temperature, or Julian date. We believe that most of the mortality was due to increased mammalian predation when access to safe aquatic habitats for resting and sheltering from predators is reduced due to lower-than-average streamflow.
Andrew S. Weber, Danielle D'Amato, Stephen J. Enders, Miranda L. McCleaf, Christopher B. Bortz, Jessica T. Weber, Ellie Campbell, Lyndsi Gilbert, Arthur E. Bogan
Many invertebrate taxa have been reported attached to the shells of turtles. Freshwater limpets (Planorbidae: Ancylinae) have a widespread distribution in North America that overlaps with many species of freshwater turtles. We have observed 5 cases of Ferrissia californica (Fragile Ancylid) attached to the shells of Glyptemys insculpta (Wood Turtle) in a Pennsylvania stream. Four instances were on live turtles, and 1 case on a deceased individual. We only observed limpets on turtles in the fall season. Herein, we report details of these observations and discuss potential advantages and disadvantages to both turtle and limpet.
We present home-range and movement-pattern analyses for a population of Glyptemys insculpta (Wood Turtle) in central Maine. We radio-tracked 27 adult turtles for 1–6 years each to characterize migration patterns, stream use, home-range sizes, and flood-displacement events. There was no significant difference between stream-emergence dates for males and females in the spring; however, males did return to the stream significantly earlier in the fall than females (male mean = 29 August, female mean = 18 September). There were also significant differences among years in emergence dates (2020 mean = 15 May, 2021 mean = 3 May, 2022 mean = 17 May), but not in return dates. On average, the maximum distance traveled from the stream during the summer months was significantly greater for females (mean = 284 m) than males (mean = 186 m). We assessed core and home-range sizes using 2 different methods but found no significant differences between males and females. Maximum occupied stream-length distances differed significantly between males (mean = 2964 m) and females (mean = 1174 m). Lastly, our analysis of flood events showed that Wood Turtles were often displaced downstream following rain events of 2 cm or greater and that larger rain events caused a greater proportion of the population to become displaced. Our Maine-based study helps to fill an important geographic gap in the literature, and our results have implications for managing Wood Turtle populations in changing environments.
Ecological studies of Glyptemys muhlenbergii (Bog Turtle) in the northern part of their range—from New England to Maryland—generally report that individuals exhibit high interannual fidelity to small, isolated, graminoid-dominated fens over periods up to several decades. However, relatively long-distance dispersal (to 4.0 km) events have been documented in southern populations from Virginia to Georgia. Studies of dispersal in Bog Turtles are generally hindered by the small size of the adult turtle, which limits the size, signal strength, and battery capacity of traditional VHF transmitters and other tracking methods. We report the apparent long-distance dispersal of a young male Bog Turtle marked at a long-term study site in Massachusetts in June 2018 and found dead on a residential homeowner's driveway 3.9 km to the north 2 years later.
We quantified mortality risk of agricultural practices on Glyptemys insculpta (Wood Turtle) via radio-tracking of 23 (6M:17F) turtles in an agri-forested landscape in 2017 and 2018. During the hay-harvesting season, ∼35% of turtle locations were within hayfields, and 86% locations of radio-tracked turtles in fields were <30 m from hayfield edges. Movement trials on 14 individuals arbitrarily placed in hayfields established that Wood Turtles can orientate towards a stream and potential safety. However, during hay harvest, Wood Turtles are unlikely to escape to safety, as none of the turtles at our study site were able to avoid the tractor as it circled the field in 5–8 minute intervals. We recommend that managers consider temporarily retaining a minimum 30 m-wide buffer strip of uncut hay along the edge of the field closest to streams during the summer harvesting season.
Radio-telemetry has provided valuable information about habitat use, movement, and ecology of reptiles. However, capture and repeated observations can be stressful for animals and may affect behavior, which could influence conclusions drawn from observations. Previous work on handling-induced stress of Glyptemys insculpta (Wood Turtle) showed a physiological response to handling, though there is currently no data on how handling may impact the spatial behavior and movement of this species. We examined the spatial effects of handling 21 adult female Wood Turtles in New Brunswick, Canada, using GPS loggers. We found that turtles moved significantly more after handling events than before, suggesting that turtles may exhibit a flight response to handling. We suggest future studies on turtles limit unnecessary interaction with study individuals and avoid using relocations in habitat-use studies for up to 50 hr after capture when studying fine-scale animal movement and habitat use.
West Virginia is located at the southwestern edge of the geographic range of Glyptemys insculpta (Wood Turtle), and there are concerns that warming temperatures with climate change could result in a northward range retraction for the species. Increasing development and conversion of habitat to incompatible land uses may exacerbate this issue. Standardized population monitoring for Wood Turtles in West Virginia began in 2020. We collected population-survey data between the fall of 2020 and fall of 2022 at 5 long-term monitoring sites to estimate population demography and adult abundances. Across the 5 sites, we captured 162 unique individuals, including 48 adult females, 92 adult males, and 22 juveniles. Estimated site-level abundances varied from 72 to 147, but confidence intervals for the estimates were wide. The large number of Wood Turtles documented during surveys and high estimated abundances suggest that populations in West Virginia are currently more robust than many other regions across the species' distribution. Our results provide baseline estimates for tracking long-term population responses to climate and land-use changes in West Virginia.
Nest predation is a conservation concern for species with low reproductive output, such as Glyptemys muhlenbergii (Bog Turtle). Over 4 years and across 9 sites in New York, we monitored 77 Bog Turtle nests and examined clutch size (n = 77; 1–5 eggs; mean = 3.3 eggs ± 0.92 S.D.), incubation periods (n = 27; 67–89 days; mean = 79.7 days ± 5.78) and temperatures, and the effectiveness of predator excluders. We compared nest-predation rates with (n = 53) and without (n = 24) predator excluders and assessed the effects of predator excluders on hatching rates and incubation timing. On average, protected nests lost 1.04 fewer eggs to predation than nests without predator excluders, and the predation rate (loss of 1 or more eggs) was 25% lower for protected nests (38%) than for unprotected nests (63%). However, the failure rate for eggs surviving predation was marginally higher for protected nests versus unprotected nests, and the number of viable hatchlings produced per nest was not statistically different between protected versus unprotected nests. Overall, our results underscore the need to monitor hatching rates in addition to predation rates when evaluating the success of predator-exclusion devices for turtle conservation.
A small relict population of Glyptemys insculpta (Wood Turtle) was discovered on a protected area in New Jersey in 2006. Marking and radio-tracking of the old founder individuals helped to determine movement patterns and habitat use. Monitoring of nesting females revealed that nesting habitat and nest success was limited due to invasive plants, human landscape alteration, and Procyon lotor (Raccoon) depredation. We initiated habitat restoration including creation of protected nesting areas, mowing in winter, invasive plant removal, and adjacent landowner education. We direct-released hatchlings from protected nests from 2006 to 2015, yet only a few were detected in subsequent years. Between 2011 and 2023, some or all of each hatchling cohort were head-started indoors at a high school for 9 months. We have continuously radio-tracked all head-starts from the 2011 cohort and portions of the 2012–2014 cohorts. Head-started turtles found their own food, established home ranges, and hibernated communally with founder adults. Subsidized Raccoons, mowers, automobiles, and flooding events—all human-instigated—were the causes of mortality. The first males and first females from the 2011 head-start cohort reached maturity in 2017 and 2019, respectively, at ages 6–8, younger than expected by 4–5 years. Successful reproduction by head-starts was confirmed by viable hatchlings produced in 2019, 2020, and 2023. Head-starting can pull a relict population out of the nose-dive to extirpation when used in conjunction with habitat-restoration practices, but it must be conducted with persistence and continuity over at least the number of years it takes for the earliest cohorts to reach maturity and begin producing offspring of their own.
To seek ways of reducing on-farm mortality of Glyptemys insculpta (Wood Turtle), we conducted radiotelemetry for 4 years at an intensively farmed river valley in eastern New York. We documented farm-related mortality of Wood Turtles, which was mostly associated with the use of a roller-crimper tractor implement on cover crops planted in organic legume and maize fields. In places where there were larger areas of the favored terrestrial forb-shrub thicket between stream channel and cropfields, the turtles were less likely to move into hazardous cultivated areas. Turtles were more likely to move into those hazardous areas during nesting forays, when summer temperatures were high, at times of high flows caused by reservoir releases, and when crossing cropfields from overwintering habitats to active-season habitats. Nesting occurred in a disused gravel pit, on gravel bars, and in cropfields.
Management actions to reduce predation of Glyptemys insculpta (Wood Turtle) nests commonly include nest cages and electric fences. However, these methods do not always effectively deter predators. Nest cages are expensive to implement because of the time required to locate nests. Electric fences can fail periodically, and some predators learn how to breach them. Herein we describe a novel nest-protection method for Wood Turtles based on designs developed by others, the “nest box”, which passively allows natural nesting and protects nest sites from depredation. The nest box consists of a lumber frame enclosed in chicken wire with a gap around the base, allowing turtles access to the site. We also compared the cost of protecting nests with nest boxes, electric fences, or nest cages. We found nest boxes to be most effective at reducing depredation, with a depredation rate of 8%, followed by nest cages (30%) and electric fences (35%). Nest boxes were also the most cost-effective nest protection method for projects lasting 3 years and longer. Given that nest boxes were effective at reducing depredation and the most cost-effective long-term protection method, we present our design as an affordable alternative to other commonly used nest-protection methods.
I observed an apparent case of kyphosis in an adult female Terrapene nelsoni (Spotted Box Turtle) from Nayarit, Mexico, and compared its measurements to a normal adult female Spotted Box Turtle also from Nayarit. Kyphosis is a congenital condition little-known in tropical Mexican turtles.
Road mortality often presents a serious conservation challenge for freshwater turtles. Population-level effects may be skewed toward either sex depending on habitat context and configuration, species, and season, and may be temporally variable. We opportunistically collected occurrence data for all turtle species encountered on roadways in the context of a 2-year radio-telemetry study. We primarily collected field data between March and August 2016 and 2017. We summarized the demographic and species composition of turtles encountered and conducted a logistic regression analysis to evaluate the influence of landscape variables associated with areas of high-density road crossings by Terrapene carolina major (Gulf Coast Box Turtle). In total, we observed 6 species of freshwater turtle on paved and unpaved roads, with 92% of records representing Gulf Coast Box Turtles. Of the roadway observations used to evaluate landscape variables, 91% of the records were Gulf Coast Box Turtles, 80% of which were females. Road crossings were associated with higher percentage of coniferous plantation and greater distance to floodplain swamp. Additionally, for all paved roads evaluated, the percent of individuals found alive varied from 58% to 89%. Our results were expected based on the radio-telemetry data collected on local populations; male box turtles in this area appeared to rely more heavily on floodplain swamps than confierous plantations. We recommend that researchers opportunistically collect road-occurrence data as feasible and coordinate with local partners to develop robust datasets that can be utilized to develop strategic mitigation measures.
Terrapene carolina bauri (Florida Box Turtle) is a species of conservation interest that ranges throughout peninsular Florida. Florida Box Turtles utilize a number of habitat types throughout the state, but limited information has been collected in the southern extent of their range. We investigated the home range (HR) and habitat usage of a coastal population of Florida Box Turtles in southwestern Florida for 3 tracking periods (2020–2021, 2021–2022, and 2022–2023) via radiotelemetry. We found variation in HR between sexes, with males exhibiting larger home-range estimates. Estimated HR was 3.68–7.54 ha for males and 1.74–2.87 ha for females depending on estimate type. We detected no significant differences in HR between tracking periods or wet and dry seasons. However, we did observe a significant interaction between season and sex indicating male HR in both seasons was greater than that of females. Our evaluation of second-order habitat selection revealed that turtles preferred coastal grassland habitat during all 3 tracking periods. Second-order selection also indicated that turtles avoided both ephemeral habitats lacking water from drought, and areas of anthropogenic influence. Third-order selection indicated variation among tracking periods in the most selected habitat, with hammock and grassland being selected for in different periods. Similarly, turtles selected against flooded grasslands and dunes. These preferences for multiple habitats may support Florida Box Turtles as an opportunistic generalist, capable of using a mosaic of habitats and resources. These data provide critical information on the ecology of a species that is understudied in the southern Florida region and may aid in conservation decisions in the future.
Translocation, the human-mediated movement of organisms, is an important tool to conserve wildlife populations, and turtles are commonly subject to this management action. One potential source stock for turtle translocations are animals confiscated from the illegal wildlife trade or otherwise held in captivity. There is limited information, however, on the post-release behavior and survival of these animals. We monitored 26 translocated long-term captive (i.e., former pet) Terrapene carolina carolina (Eastern Box Turtle) to assess their survivorship, space use, and the effects of soft-release (penning) on site fidelity. We found long-term captives displayed high first-year survivorship (88.5–92.3%) and similar space use to resident turtles, and that soft-release was effective at reducing post-release movements. Our study indicates long-term captive turtles may be suitable for release and provides insights for how confiscated turtles may best contribute to conservation.
In 2020, natural resource managers at Camp Edwards, Barnstable County, MA, observed Terrapene carolina carolina (Eastern Box Turtle) individuals infected by myiasis, where parasitic flesh flies larviposit into the living tissue of a host. The hypothesized parasite was Dexosarcophaga cistudinis, but its impacts on the host's body condition, movement, and habitat use were unknown. Our objectives were to identify the parasite at Camp Edwards and to compare the body condition, movement, and habitat characteristics at capture locations of Eastern Box Turtles for infected and noninfected individuals. We radio-tracked turtles weekly and encountered 48 individuals from May to August 2022 at Camp Edwards, MA. Upon capture, we recorded turtle infection status, mass, carapace length, shell surface temperature, GPS location, and habitat characteristics of the capture location. We confirmed D. cistudinis as the parasite and found that myiasis-infected turtles had a significantly higher shell temperature (27.92 ± 5.28 °C) than noninfected turtles (26.77 ± 5.64 °C). However, we did not find an effect of myiasis on body condition, habitat use, or average daily distance moved. Collectively, our results suggest that infected turtles may exhibit behavioral fever, a mechanism by which ectotherms move to warmer microclimates to raise their body temperature in response to infections. Eastern Box Turtles at Camp Edwards may be able to use behavioral fever in response to myiasis infection because of the habitat mosaic made available through detailed habitat-management regimes.
I studied population demography and life-history trait variation of Terrapene ornata (Ornate Box Turtle) from 1981 to 2019 on and near the Crescent Lake National Wildlife Refuge in the Sandhills of western Nebraska. Most captures were made along drift fences (∼1200 m) between wetland and upland habitats (609 individually marked turtles captured 2684 times), supplemented by data from telemetry of 37 females, and dissections of road-killed animals. The adult sex ratio was 1.5 females per male. Recapture histories for data from 1981 to 2000 indicated annual female survival rates of 0.932. Survival of juveniles (based on actual captures) were 0.86 for the first year after spring emergence, 0.932/ yr for the next 2 years, and 0.99/yr for the next 8 activity seasons. Based on recaptures, females reach maturity in 12–16 years (14 being typical) at ∼110 mm plastron length (100 mm carapace length). Long-term capture histories (12–37 yrs) of 37 full adults nearly all showed positive slopes, and 14 had slopes significantly greater than zero, suggesting indeterminate growth. Some telemetered females appeared to nest within their home ranges, but some undertook forays over 1 km away. All observed nesting (n = 22; 28 May–17 June) was overnight into the early morning. Clutch size varied from 1 to 6 eggs (mean = 3.6) and tended to increase with body size, but egg size (mean = 11.9 g) was not related to body size. Clutch mass averaged 11.3% of gravid female body mass. Individual females produced 0–2 clutches/year. Upon hatching, neonates buried below or near their nest site and descended to nearly 1 m below the surface for their first winter. Survival of 21 nests to hatching was 57.1%, but only 7 hatchlings from an estimated 75 eggs (9.4%) were recovered from those nests the following spring. Survival analyses indicated that the population increased by about 22% per generation (∼28 yr). The importance of the permanent wetland for hydration associated with nesting and for summer estivation was clear based on my telemetry and recapture data.
Turtle movement patterns are influenced by foraging, searching for mates, shelter, and thermoregulating. Movements can be influenced by intrinsic characteristics of the organisms, such as sex and age, but also by extrinsic factors such as seasonal changes, availability of food, and the need to find microhabitats for long inactive periods such as estivation and brumation. Terrapene coahuila (Coahuila Box Turtle) is the only aquatic species of Terrapene and inhabits the wetlands of Cuatro Ciénegas, Coahuila, in northern Mexico. This study describes the movement patterns and the home range of adult Coahuila Box Turtles, and the influence of pronounced seasonality in the wetland system of the Cuatro Ciénegas Valley on the species' behavioral ecology. The average daily linear distances traveled by adults during the wet–warm, wet–cold, and dry–warm seasons were 36.76, 21.38, and 32.18 m, respectively. The daily distance travelled was not statistically different between males and females or among seasons. The average number of movements was affected by seasonal conditions, with a marked reduction in the wet–cold season. The average home ranges for wet–warm, wet–cold, and dry–warm seasons were 0.91, 0.60, and 0.25 ha, respectively, using the fixed kernel method (FK), and 4.68, 1.48, and 5.09 ha, respectively, using the minimum convex polygon method (MCP). There were no significant differences in home-range size between sexes or among seasons using FK but there were using MCP (the latter being smaller during the wet–cold season). Seasonal differences in movement patterns may reflect seasonal changes in the habitat as well as other landscape attributes that might be involved in the spatial ecology of the species.
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