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At least 703 records · Page 39Linked to original sources
USGS2013

Home range characteristics and overwintering ecology of the stripe-necked musk turtle ( Sternotherus minor peltifer ) in middle Tennessee

Little is known about the movement behavior of the stripe-necked musk turtle, Sternotherus minor peltifer . Using radiotelemetry, we calculated mean (± SD) home range length, which was 341.4 ± 90.3 m, with home range length not differing between the sexes (males, 335 ± 194 m; females, 346 ± 79.5 m). Sternotherus m. peltifer were active in every month of the year but decreased their movement distance and frequency between December and March; during nonwinter and winter periods, individuals used limestone bluffs most often.

Tennessee↗
USGS2013

Nest site selection by diamond-backed terrapins (Malaclemys terrapin) on a Mid-Atlantic Barrier Island

We scored 48 Malaclemys terrapin nests destroyed by raccoons on Fisherman Island, Virginia, for the presence or absence of tree canopy, shrub canopy, no canopy, bare sand, grass cover, and herbaceous cover. Significantly more nests than expected were found in the open with no vegetation cover and observed distances of predator-destroyed nests from the edge of the nearest habitat island of woody vegetation were significantly different from a normal distribution; most were placed near the island margin. Our results underscore the need to understand the influence of predator search behavior on terrapin nest survival in different habitat types.

Chelonian Conservation and Biology↗
USGS2016

Diet of diamondback terrapins (Malaclemys terrapin) in subtropical mangrove habitats in South Florida

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

Florida↗
USGS2016

Head-started Kemp’s ridley turtle ( Lepidochelys kempii ) nest recorded in Florida: Possible implications

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

Florida↗
USGS2017

Hatching success and predation of Bog Turtle (Glyptemys muhlenbergii) eggs in New Jersey and Pennsylvania

Nest-site selection by most turtles affects the survival of females and their offspring. Although bog turtles ( Glyptemys muhlenbergii ) do not typically leave their wetlands for nesting, nest-site selection can impact hatching success and hatchling survival. Between 1974 and 2012, we monitored the fates of 258 bog turtle eggs incubated in the field and 91 eggs incubated under laboratory conditions from 11 different bogs, fens, or wetland complexes in New Jersey and Pennsylvania. Laboratory-incubated eggs exhibited the greatest hatching success (81%), but we did not detect a significant difference in hatching success between nests protected with predator excluder cages (43%) and unprotected nests (33%). However, we found significantly lower predation rates in protected nests, suggesting that while predator excluder cages successfully reduced predation, other environmental factors persisted to reduce egg survival in the field. Natural hatching success was potentially reduced by poor weather conditions, which may have resulted in embryo developmental problems, dehydration, or embryos drowning in the egg. Our results suggest that egg depredation, coupled with embryo developmental problems and infertility, are limiting factors to hatching success in our study populations. Using predator excluder cages to protect bog turtle eggs in the field, or incubating eggs in the laboratory and releasing hatchlings at original nesting areas, may be an effective conservation tool for recovering populations of this federally threatened species.

New Jersey, Pennsylvania↗
USGS2017

Seasonal and diel environmental conditions predict western pond turtle (Emys marmorata) behavior at a perennial and an ephemeral stream in Sequoia National Park, California

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

California↗
USGS2018

Crowding affects health, growth, and behavior in headstart pens for Agassiz's desert tortoise

Worldwide, scientists have headstarted threatened and endangered reptiles to augment depleted populations. Not all efforts have been successful. For the threatened Agassiz's desert tortoise ( Gopherus agassizii ), one challenge to recovery is poor recruitment of juveniles into adult populations, and this is being addressed through headstart programs. We evaluated 8 cohorts of juvenile desert tortoises from 1 to 8 yrs old in a headstart program at Edwards Air Force Base, California, for health, behavior, and growth. We also examined capacities of the headstart pens. Of 148 juveniles evaluated for health, 99.3% were below a prime condition index; 14.9% were lethargic and unresponsive; 59.5% had protruding spinal columns and associated concave scutes; 29.1% had evidence of ant bites; and 14.2% had moderate to severe injuries to limbs or shell. Lifetime growth rates for juveniles 1–8 yrs of age were approximately two times less than growth rates reported for wild populations. Tortoises in older cohorts had higher growth rates, and models indicated that high density in pens and burrow sharing negatively affected growth rates. Densities of tortoises in pens (205–2042/ha) were 350–3500 times higher than the average density recorded in the wild (< 1/ha) for tortoises of similar sizes. The predominant forage species available to juveniles were alien annual grasses, which are nutritionally inadequate for growth. We conclude that the headstart pens were of inadequate size, likely contained too few shelters, and lacked the necessary biomass of preferred forbs to sustain the existing population. Additional factors to consider for future reptilian headstart pens include vegetative cover, food sources, soil seed banks, and soil composition.

California↗
USGS2018

Factors affecting nesting ecology of Apalone spinifera in a northwestern Great Plains river of the United States

The nesting ecology of Apalone spinifera in large North American rivers is largely unknown despite the wide distribution of the species in these naturally dynamic ecosystems. We describe the nesting locations, timing, behavior, and habitat of A. spinifera in relation to natural and anthropogenic factors in the Missouri River. Nesting followed annual peak river stage, mostly occurred in the afternoon when air temperatures were 25°–30°C, and did not occur when human activity was nearby. Apalone spinifera nested in June in a year with average discharge (2012), but nested 20 d later in a year with a large flood event (2011). During the average discharge year, 90% of nests were found on islands, but similar proportions of nests were found on island and mainland habitats during the flood year because many islands were inundated. Nests were mostly in mixed-gravel substrates where vegetation cover was sparse or absent. Depredation occurred only after the emergence of hatchlings (∼ 60 d after nesting) and more often on nests on the mainland than on islands. Emergence rates were ∼ 1.5 times higher in the average year than the flood year, and emergence rates were higher in mixed-gravel nests than in pure-sand nests in 2011. In artificial nests, incubation temperatures averaged ∼ 4.3°C higher in mixed-gravel than in sand substrates, and freezing temperatures in winter penetrated to depths greater than the mean egg chamber depth (7.5 cm) for up to 3 wks. Therefore, incubation might be accelerated in mixed-gravel substrates. Accelerated incubation would enhance reproductive success because freezing temperatures preclude hatchlings from overwintering in nests in our study area. Mountain snowmelt-driven hydrology, coupled with the onset of freezing temperatures in autumn, might create a temporal “runoff-freeze squeeze” that limits the successful reproduction of A. spinifera in some years. However, high runoff also scoured vegetation from shorelines where A. spinifera nested in subsequent years. Natural variation in annual discharge might therefore be crucial to conservation of A. spinifera in large rivers.

Chelonian Conservation and Biology↗
USGS2018

Global conservation status of turtles and tortoises (order Testudines)

We present a review and analysis of the conservation status and International Union for Conservation of Nature (IUCN) threat categories of all 360 currently recognized species of extant and recently extinct turtles and tortoises (Order Testudines). Our analysis is based on the 2018 IUCN Red List status of 251 listed species, augmented by provisional Red List assessments by the IUCN Tortoise and Freshwater Turtle Specialist Group (TFTSG) of 109 currently unlisted species of tortoises and freshwater turtles, as well as re-assessments of several outdated IUCN Red List assessments. Of all recognized species of turtles and tortoises, this combined analysis indicates that 20.0% are Critically Endangered (CR), 35.3% are Critically Endangered or Endangered (CR+EN), and 51.9% are Threatened (CR+EN+Vulnerable). Adjusting for the potential threat levels of Data Deficient (DD) species indicates that 56.3% of all data-sufficient species are Threatened. We calculated percentages of imperiled species and modified Average Threat Levels (ATL; ranging from Least Concern = 1 to Extinct = 8) for various taxonomic and geographic groupings. Proportionally more species in the subfamily Geoemydinae (Asian members of the family Geoemydidae) are imperiled (74.2% CR+EN, 79.0% Threatened, 3.89 ATL) compared to other taxonomic groupings, but the families Podocnemididae, Testudinidae, and Trionychidae and the superfamily Chelonioidea (marine turtles of the families Cheloniidae and Dermochelyidae) also have high percentages of imperiled species and ATLs (42.9–50.0% CR+EN, 73.8–100.0% Threatened, 3.44–4.06 ATL). The subfamily Rhinoclemmydinae (Neotropical turtles of the family Geoemydidae) and the families Kinosternidae and Pelomedusidae have the lowest percentages of imperiled species and ATLs (0%–7.4% CR+EN, 7.4%–13.3% Threatened, 1.65–1.87 ATL). Turtles from Asia have the highest percentages of imperiled species (75.0% CR+EN, 83.0% Threatened, 3.98 ATL), significantly higher than predicted based on the regional species richness, due to much higher levels of exploitation in that geographic region. The family Testudinidae has the highest ATL (4.06) of all Testudines due to the extinction of several species of giant tortoises from Indian and Pacific Ocean islands since 1500 CE. The family Testudinidae also has an ATL higher than all other larger polytypic families (≥ 5 species) of Reptilia or Amphibia. The order Testudines is, on average, more imperiled than all other larger orders (≥ 20 species) of Reptilia, Amphibia, Mammalia, or Aves, but has percentages of CR+EN and Threatened species and an ATL (2.96) similar to those of Primates and Caudata (salamanders).

Chelonian Conservation and Biology↗
USGS2020

Development of a genotyping protocol for Mojave desert tortoise scat

Noninvasive fecal genotyping can be a useful tool for population monitoring of elusive species. We tested extraction protocols on scat samples from the threatened Mojave Desert tortoise, Gopherus agassizii, to evaluate whether scat-based mark–recapture and population genetic monitoring studies are feasible.We extracted DNA from G. agassizii scat samples collected in California and Nevada using several extraction protocols and evaluated the reliability of resulting genotypes using quality scores, maximum likelihood reliability estimates, and paired scat and blood genotypes from the same individuals. Finally, we assessed probabilities of identity and sibship, and locus amplification quality, and calculated genotyping error rates for 19 microsatellite loci to determine the best set of loci to use with G. agassizii scat extractions. We found that genotype quality depended more on the sample quality than on the extraction method, and that the Qiagen DNeasy Plant Mini extraction kit is an efficient method for extracting tortoise DNA from tortoise scat. We identified 6 G. agassizii microsatellite loci that can be used to generate a unique molecular tag for individual tortoises. We characterized the reliability of an additional 13 microsatellite loci for use in population genetic analyses where additional power at the expense of some increase in error may be advantageous. As proof of concept, with very low error rates, we matched 3 opportunistically collected scat samples to blood genotypes from animals captured during population surveys within the study area and discovered at least 3 new individuals, even after 2 yrs of extensive survey work. These results suggest that genotyping of field-collected scat can complement existing methods used in long-term demographic and movement studies of G. agassizii and other, closely related, tortoise species.

California↗
USGS2020

Dispersal of hatchling Ouachita map turtles (Graptemys ouachitensis) from natural nests on the lower Wisconsin River, Wisconsin, USA

Despite its importance to individual fitness and population dynamics, the dispersal behaviors of most neonate freshwater turtles after nest emergence are poorly known. We studied the initial dispersal tendencies of neonate Ouachita map turtles ( Graptemys ouachitensis ) exiting natural nests during 2015–2017 along the Wisconsin River, Wisconsin. Overall, dispersal was nonrandom, and hatchlings largely oriented toward the nearest substantial vegetative cover, a woodland north of the nesting area. However, variation sometimes occurred in routes taken among hatchlings within a clutch. Directional changes within an individual's dispersal track, including route reversals, were also observed. As our work appears to be the first to use standalone trail cameras as a primary data-gathering tool for a hatchling dispersal study, it highlights the potential benefits and limitations of this technique for similar research.

Wisconsin↗
USGS2024

Diet of Dermatemys mawii, an aquatic turtle that relies heavily on terrestrial vegetation

Dermatemys mawii is a critically endangered freshwater turtle endemic to Central America. In the wild, these turtles are thought to be wholly herbivorous as adults and feed on a variety of vegetation; however, no studies have quantitatively assessed potential dietary differences based on biotic and abiotic factors. The purpose of our study was to describe and quantify the wild diet of D. mawii and assess differences based on habitat, maturity, and sex. We evaluated the stomach contents of 66 turtles legally harvested by local hunters for personal consumption throughout the country of Belize. Percent volume (by displacement) and percent frequency of each stomach item were used to calculate an index of relative importance (IRI). One algal and 6 plant families contributed to an overall diet composition consisting of leaves, flowers, stems, seedpods, seeds, and fruit. Rocks and invertebrates were also consumed, although we believe these to be incidental consumption. The leaves of the riparian tree Inga edulis were present in 73.1% of turtle stomachs and accounted for almost half of the total volume of all stomach contents combined. We used Spearman rank correlation coefficients to test the null hypothesis that there was no correlation in the rankings of stomach items (i.e., there were differences) when comparing turtles by habitat, age, and sex. There were significant differences in the ranking of food items between river and lagoon habitats, with lagoon turtles relying heavily on the algae Nitella sp.; however, the stomach contents from both habitats were equally diverse (H rivers = 1.68, H lagoons = 1.64). There were no differences in IRIs between adults and juveniles or between males and females. Our results emphasize the importance of habitat in D. mawii diet selection and the importance of leaves from riparian plants species that are shed into their aquatic habitats.

Chelonian Conservation and Biology↗
USGS2024

Comparison of two methods to detect the northwestern pond turtle (Actinemys marmorata) and the invasive American bullfrog (Lithobates catesbeianus) in interior northern California

Knowledge about the distributions of species and the variables influencing their occurrence is important for their management and conservation, but factors affecting occurrence can vary across the range of a species. Northwestern pond turtles ( Actinemys marmorata ) are widespread generalist turtles, but are nonetheless of conservation concern throughout their range. To better understand the distribution of northwestern pond turtles and introduced American bullfrogs ( Lithobates catesbeianus ), we surveyed streams on private timberlands of the interior foothills of northern California using visual encounter surveys and collecting samples of environmental DNA. We found that northwestern pond turtle occurrence was negatively related to elevation in our sampling frame. Detection probabilities with environmental DNA were approximately twice those of visual encounter surveys, but both methods were effective for detecting turtles in streams. American bullfrogs were detected in a single sample at each of 2 sites (one by environmental DNA, one by visual encounter surveys). Management for northwestern pond turtles in forest streams within our sample area will likely have the largest effect at lower elevation sites where turtles are most likely to occur.

California↗
USGS2025

Arsenic accumulation in Sonora Mud Turtles (Kinosternon sonoriense) in an unusual freshwater food web

Montezuma Well is an unusual fishless, spring-fed, desert wetland in central Arizona. Water in the wetland is naturally enriched with > 100 µg/l dissolved geogenic arsenic (As) and supports a simple aquatic food web dominated by a small number of endemic invertebrate species that achieve high abundances. Previous studies of As among various environmental compartments and organisms in Montezuma Well did not include omnivorous Sonora Mud turtles ( Kinosternon sonoriense ) despite their potential importance in the As cycle by virtue of their substantial biomass and role as top predators. We measured As concentrations in water, sediment, and organisms (macrophytes, amphipods, insects, leeches, and turtles) representing a range of trophic levels in order to document the importance of turtles at the apex of the Montezuma Well food web and in the As cycle. Concentrations of As in turtles varied according to tissue type. The greatest values (up to 26.77 mg/kg dry weight) were in the scutes of 1 of our oldest turtles (31.5 yrs). These elevated concentrations may be due to the affinity of As to react with sulfur in the keratin of scutes, and therefore might reflect duration of exposure in long-lived turtles. Although As concentrations generally tend to decrease when moving up to higher trophic levels in a food web, our results were different. Relatively elevated concentrations reported in sediments by us and a previous study declined in plant samples as expected. Amphipod concentrations increased but then decreased again in 3 of their invertebrate predators. Arsenic concentrations in endemic leeches were extremely elevated with a mean value of 72.2 mg/kg. The mean concentration of As in turtles was 7.08 mg/kg across tissue types and was greater than the plants or invertebrates they eat, with the notable exception of leeches, which have been proposed to be part of their diet.

Arizona↗
USGS2025

Freshwater turtle assemblages and densities in agricultural ditches and aquaculture ponds of eastern Arkansas

The Mississippi Alluvial Plain (MAP) of Arkansas is a landscape where many wetlands have been altered for use as aquaculture ponds or agricultural ditches. Commercial harvest of freshwater turtles within the MAP is not restricted or limited, with reported harvest numbers for 2019 alone exceeding 4000 for spiny softshell turtles ( Apalone spinifera ) and 39,000 for red-eared sliders ( Trachemys scripta elegans ). Herein, we attempt to provide baseline estimates of freshwater turtle densities and community composition in aquaculture ponds and agricultural ditches of eastern Arkansas, the habitat types most frequently trapped by commercial harvesters. We used a capture–mark–recapture approach over 3 summers (2019–2021) to evaluate population densities and community composition of freshwater turtles in these anthropogenic aquatic habitats. We captured > 4000 individuals of 9 species of turtle. One species, the red-eared slider, dominated the turtle community in both anthropogenic aquatic habitats, comprising 66% (± 22% SD) of all captures in agricultural ditches and 63% (± 32% SD) in aquaculture ponds. Diversity and richness did not differ between aquaculture ponds and agricultural ditches. We estimated densities of the 2 most commonly captured species, the red-eared slider and spiny softshell turtle. Density of red-eared sliders ranged from 0 turtles/unit area (linear kilometers in ditches or hectares in ponds) to 500 turtles/unit area, with a median of 37 turtles/unit area. The spiny softshell turtle was more frequently captured in ponds than ditches and attained average densities of 25 (± 19) turtles/ha and 7 (± 4) turtles/linear km, respectively. Our mean density estimates were lower than those in reported literature, including estimates from similar habitats, such as urban ditches and farm ponds, which resemble our study sites in structure, use, and geographical placement. We estimate the region contains 22,317 ha of aquaculture ponds and 18,350 linear km of agricultural ditches. By extrapolating our density estimates to each anthropogenic aquatic habitat type, we estimated 2 million red-eared sliders and 427,000 spiny softshell turtles occurred in aquaculture ponds and agricultural ditches across eastern Arkansas. Our results suggest that these altered wetlands provide abundant habitat for only a few generalist turtle species.

Arkansas↗
USGS2021

Invasive black carp as a reservoir host for the freshwater mollusk parasite Aspidogaster conchicola: Further evidence of mollusk consumption and implications for parasite dispersal

Black Carp ( Mylopharyngodon piceus ) has invaded the Mississippi River and is a potential threat to native mollusks. During prior diet research, we discovered that the fluke Aspidogaster conchicola , a mollusk parasite, occurs regularly in the gastrointestinal tract of Black Carp. The fluke remains in fish intestines for extended periods after the fish has consumed its host. Flukes were found in 33% of the wild Black Carp examined, and numbers ranged from 1 to 802, with no pattern evident across seasons of fish capture. Treating the flukes as indicators of prior mollusk consumption, we adjusted the percent occurrence of mollusks from 26.6% to 54.1%, indicating that the previously reported incidences for bivalves (22.8%) and gastropods (16.5%) in the diet of wild Black Carp are likely to be underestimated. Based on percent occurrences in Black Carp, larger fish (>791 mm) had significantly higher fluke occurrence (42.6%) and fish captured from lentic habitats had significantly greater fluke-adjusted mollusk occurrence (87.5%). These diet-occurrence estimates, coupled with the presence of gravid A. conchicola and evidence of their continued viability in Black Carp intestines, indicate that these fish retain evidence of mollusk consumption for extended periods after evacuation of the gastrointestinal tract. Consequently, Black Carp has the potential to disperse this parasite to other mollusks.

Arkansas, Illinois, Kentucky, Louisiana, Mississip↗
USGS2022

Assessment of a habitat equivalency analysis for freshwater mussels in the upper Mississippi River

The upper Mississippi River (UMR) contains diverse, dense, and reproducing assemblages of native freshwater mussels. In the case of an injury to mussels and their habitats, such as a hazardous material spill, train derailment, or barge grounding, resource managers have few restoration strategies. Resource managers need a means to document, quantify, and mitigate adverse effects on mussels resulting from injury. Habitat equivalency analysis (HEA), developed for use with a wide variety of habitat types, is a restoration scaling technique that compares ecological services lost from injury to ecological services gained through restoration actions. The U.S. Fish and Wildlife Service and Iowa Department of Natural Resources modified the HEA for use with native mussels. The mussel HEA has been applied within the UMR to estimate the quantity of restoration needed to compensate the public for injuries to mussels due to contaminant spills and construction projects. Our objective was to describe the UMR HEA for a general audience and assess if the four biological input variables used in the mussel HEA were reasonable based on literature values. We also evaluated the performance of HEA under a range of input scenarios. Although the input estimates used in HEA were within ranges reported in the peer-reviewed literature or were supported by professional judgment in the absence of peer-reviewed literature, outcomes of the mussel HEA were highly variable and would benefit from additional research to reduce uncertainty in the biological inputs. The application of HEA to mussels provides resource managers with a tool to quantify mussel-related ecological services lost from injury and to guide restoration efforts in the UMR.

Freshwater Mollusk Biology and Conservation↗
USGS2023

Further bacteriological analysis of annual Pheasantshell (Actinonaias pectorosa) mussel mortality events in the Clinch River (Virginia/Tennessee), USA, reveals a consistent association with Yokenella Regensburgei

Pheasantshell ( Actinonaias pectorosa ) mussels in the Clinch River (Tennessee/Virginia, USA) have declined dramatically in recent years. The bacterium Yokenella regensburgei was first isolated with high prevalence from Pheasantshells during the peak of a 2017 mortality event, but it was not identified after mortality subsided a few months later. Since 2017, Pheasantshell mortality in the Clinch River has occurred each autumn. We extended the investigation of culturable bacterial communities in the Clinch River during mussel mortality events in 2018, 2019, and 2020 and examined the spatial and temporal distribution of bacterial genera among Pheasantshells, as well as among other unionid mussels. We identified Y. regensburgei each year, almost exclusively during active mortality events. The significance of Y. regensburgei remains unclear, but the continued association of this bacterium with mussel mortality events warrants further study.

Tennessee, Virginia↗