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Advances in the Biology and Conservation of Turtles
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Advances in the Biology and Conservation of Turtles

A special issue of Diversity (ISSN 1424-2818). This special issue belongs to the section "Animal Diversity".

Deadline for manuscript submissions: closed (31 March 2019) | Viewed by 86329

Special Issue Editor

Prof. Russell L. Burke

E-Mail Website
Guest Editor
Department of Biology, Hofstra University, Hempstead, NY, USA
Interests: chelonian ecology and conservation

Special Issue Information

Dear Colleagues,

The approximately 356 species of testudines (turtles) are remarkable for their blend of phylogenetic conservatism and diversity. A few species thrive in the Anthropocene, yet many are among the most highly endangered vertebrates. Turtles have wide-spread public charisma, yet populations are hunted to near extinction for imaginary medicinal properties. In recent years, there has been a dramatic increase in research into the biology and conservation of turtles globally, especially regarding species that previously have received relatively little attention. New research has been aided by the use of traditional and cutting-edge techniques, from the use of tracking dogs to drones and eDNA. The development of well-supported turtle phylogenies makes interspecific comparisons particularly appealing. This Special Issue provides a venue to highlight relatively novel and robust analyses and experiments involving turtles—understudied species, interspecific comparisons, new or neglected techniques. Each manuscript should have clear conservation implications.

Prof. Russell L. Burke
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Diversity is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Turtle
  • Conservation
  • Biodiversity
  • Comparison

Published Papers (17 papers)

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Editorial

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3 pages, 172 KiB  
Editorial
Advances in the Biology and Conservation of Turtles
by Russell L. Burke
Diversity 2021, 13(1), 17; https://0-doi-org.brum.beds.ac.uk/10.3390/d13010017 - 06 Jan 2021
Viewed by 2205
Abstract
The approximately 356 species of testudines (turtles) are remarkable for their blend of phylogenetic conservatism and diversity [...] Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)

Research

Jump to: Editorial, Review

11 pages, 2646 KiB  
Article
Poor Correlation between Diamondback Terrapin Population Estimates Using Two New Estimation Methods
by Lisa Prowant and Russell L. Burke
Diversity 2020, 12(11), 409; https://0-doi-org.brum.beds.ac.uk/10.3390/d12110409 - 23 Oct 2020
Cited by 2 | Viewed by 2368
Abstract
Reliable estimates of animal and plant population sizes are necessary to track trends in populations through time. Diamondback terrapins are an ecologically unique keystone species that are globally declining. Conservation efforts for this species rely on accurate estimates of population sizes; however, diamondback [...] Read more.
Reliable estimates of animal and plant population sizes are necessary to track trends in populations through time. Diamondback terrapins are an ecologically unique keystone species that are globally declining. Conservation efforts for this species rely on accurate estimates of population sizes; however, diamondback terrapin population size estimates are difficult to measure with precision or accuracy. Terrapin collection methods are often labor-, time-, and cost-intensive. The present study compares two recently developed rapid assessment methods for measuring diamondback terrapin abundances. Since mark–recapture or similar data were unavailable, we could not test the accuracy of either method directly; instead, we compared the two methods. If the methods produce similar estimates of terrapin population size, this would increase confidence in these methods. We measured the abundance of diamondback terrapins at 77 sites in Long Island, New York, using headcount surveys and surveys of parasitic trematodes that can be used as a proxy for terrapin abundance. We used random forest analyses to test whether the variation in diamondback terrapin abundance measured using headcount surveys could be explained by either the prevalence or the abundance of trematode parasites. The most variation explained by any of the models was 7.77%, indicating that trematode prevalence and abundance could not explain the variation in terrapin abundance measured using headcounts. This poor correlation between terrapin census methods indicates that one, or both, of the census measures are inaccurate, at least in the habitats found across Long Island, NY. A technique that accurately estimates the abundance of diamondback terrapin populations is critical to understanding their population fluctuations and trends. The only way to evaluate the status of the species is to have information on population numbers and trends across the species’ range, which might not be possible without a more accessible survey method. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
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12 pages, 271 KiB  
Article
The Role of Nest Depth and Site Choice in Mitigating the Effects of Climate Change on an Oviparous Reptile
by Rebecca A. Czaja, Amanda L. Scholz, Miranda P. Figueras and Russell L. Burke
Diversity 2020, 12(4), 151; https://0-doi-org.brum.beds.ac.uk/10.3390/d12040151 - 16 Apr 2020
Cited by 12 | Viewed by 3720
Abstract
Climate change is likely to have strong impacts on oviparous animals with minimal parental care, because nest temperature can impact egg development, sex, and survival, especially in the absence of mitigation via parental care. Nesting females may compensate for increasing temperatures by altering [...] Read more.
Climate change is likely to have strong impacts on oviparous animals with minimal parental care, because nest temperature can impact egg development, sex, and survival, especially in the absence of mitigation via parental care. Nesting females may compensate for increasing temperatures by altering how, when, and where they nest. We examined the factors determining nest depth and site choice as well as the effects that nest depth and location have on nest temperature and hatching success in the diamondback terrapin (Malaclemys terrapin). We found that nest depth was not correlated with nesting female size, egg characteristics, or daily temperatures. Nest temperatures and hatching success were correlated with different environmental and nest characteristics between 2004, a cool and wet year, and 2005, a hot and dry year. Females selected nests with lower southern overstory vegetation in 2005. These results suggest that nest depth and location can play an important yet varying role in determining nest temperature and hatching success in more extreme warm and dry environmental conditions and, therefore, may mitigate the impacts of climate change on oviparous reptiles. However, we found minimal evidence that turtles choose nest locations and depths that maximize offspring survival based on short-term environmental cues. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
23 pages, 2755 KiB  
Article
A Long-Term Demographic Analysis of Spotted Turtles (Clemmys guttata) in Illinois Using Matrix Models
by Christina Y. Feng, Jason P. Ross, David Mauger and Michael J. Dreslik
Diversity 2019, 11(12), 226; https://0-doi-org.brum.beds.ac.uk/10.3390/d11120226 - 26 Nov 2019
Cited by 12 | Viewed by 5334
Abstract
Matrix models and perturbation analyses provide a useful framework for evaluating demographic vital rates crucial to maintaining population growth. Determining which vital rates most influence population growth is necessary for effective management of long-lived organisms facing population declines. In Illinois, the state-endangered Spotted [...] Read more.
Matrix models and perturbation analyses provide a useful framework for evaluating demographic vital rates crucial to maintaining population growth. Determining which vital rates most influence population growth is necessary for effective management of long-lived organisms facing population declines. In Illinois, the state-endangered Spotted Turtle (Clemmys guttata) occurs in two distinct populations, and management can benefit from an understanding of its demographic behavior. We conducted a mark–recapture study on both populations in 2015 and 2016 and used historical mark–recapture data from 1988 to 2010 to determine female age-specific survival and fecundity rates. Survival increased significantly with age, and age-specific reproductive output and fecundity were >1.0. However, both populations exhibited net reproductive rates below replacement levels, and one population had a negative growth rate. Summed elasticities for all adult age classes indicate adult survival has the highest proportional impact on population growth. We found evidence of demographic divergence between the two populations, and thus the prioritization of vital rates varied somewhat between sites, with a relatively higher emphasis on juvenile and young adult survival for one population. We recommend conservation actions such as habitat management and predator control, which will have positive impacts across stage classes. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
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22 pages, 69074 KiB  
Article
Movement and Home Range of the Smooth Softshell Turtle (Apalone mutica): Spatial Ecology of a River Specialist
by Jason P. Ross, Robert D. Bluett and Michael J. Dreslik
Diversity 2019, 11(8), 124; https://0-doi-org.brum.beds.ac.uk/10.3390/d11080124 - 26 Jul 2019
Cited by 6 | Viewed by 5338
Abstract
Spatial ecological information is necessary to guide the conservation efforts of river turtles, but it is lacking for many species including the smooth softshell turtle (Apalone mutica). We investigated the spatial ecology of A. mutica in two reaches of the Kaskaskia [...] Read more.
Spatial ecological information is necessary to guide the conservation efforts of river turtles, but it is lacking for many species including the smooth softshell turtle (Apalone mutica). We investigated the spatial ecology of A. mutica in two reaches of the Kaskaskia River in Illinois, USA to determine variables influencing movement rates, the best estimate of home range, and variables influencing home range size. We radio-tracked 28 A. mutica from 2013 to 2014 and used an information theoretic approach to select the best models describing movement and home range estimates. Mean movement rate was 142.3 m/day and was highly variable with some movements >2 km/day. Movement peaked at moderate water temperatures early in the active season, increased at higher water levels for females, and was greater in the higher stream order. The sexes responded differently to environmental variation, with female movement higher in most but not all conditions. The most informative home range estimate was a 95% kernel density estimate using likelihood cross-validation (CVh) smoothing clipped to the river channel. The mean home range size was 18.1 hectares and increased with movement rate, number of radio-locations, and stream order. Most turtles had well-defined home ranges, though a few were possibly nomadic. Our methods also provide a framework for spatial ecological studies of other riverine species. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
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11 pages, 2294 KiB  
Article
GIS-modeling of the Range Shifts of the Sub-fossil and Extant European Pond Turtle (Emys orbicularis) in Eastern Europe in Holocene
by Oksana Nekrasova, Yevheniia Yanish, Volodymyr Tytar and Mihails Pupins
Diversity 2019, 11(8), 121; https://0-doi-org.brum.beds.ac.uk/10.3390/d11080121 - 26 Jul 2019
Cited by 4 | Viewed by 4821
Abstract
The study of the dynamics of the European pond turtle’s Emys orbicularis range and distribution as an indicator of climate change in the past, present, and future is most relevant in connection with the protected status of this species in Europe. Based on [...] Read more.
The study of the dynamics of the European pond turtle’s Emys orbicularis range and distribution as an indicator of climate change in the past, present, and future is most relevant in connection with the protected status of this species in Europe. Based on our original finds, 25 archaeological sites yielding 1623 remains of 1504 individuals of subfossil pond turtles, current marginal distribution in Latvia, Ukraine, Russia, and literature data, we analyzed 437 records of Holocene turtles and 2847 current records of pond turtles. We identified areas that could serve as refugia for E. orbicularis, as a result of GIS modeling, while using 19 bioclimatic variables from the Worldclim and PaleoClim data bases. The data obtained confirm current hypotheses regarding the origin of more than 10 mtDNA lineages of E. orbicularis and the existence of multiple glacial refugia, and considerable Holocene home range dynamics. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
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15 pages, 1953 KiB  
Article
Visual Head Counts: A Promising Method for Efficient Monitoring of Diamondback Terrapins
by Patricia Levasseur, Sean Sterrett and Chris Sutherland
Diversity 2019, 11(7), 101; https://0-doi-org.brum.beds.ac.uk/10.3390/d11070101 - 27 Jun 2019
Cited by 8 | Viewed by 4204
Abstract
Determining the population status of the diamondback terrapin (Malaclemys terrapin spp.) is challenging due to their ecology and limitations associated with traditional sampling methods. Visual counting of emergent heads offers a promising, efficient, and non-invasive method for generating abundance estimates of terrapin [...] Read more.
Determining the population status of the diamondback terrapin (Malaclemys terrapin spp.) is challenging due to their ecology and limitations associated with traditional sampling methods. Visual counting of emergent heads offers a promising, efficient, and non-invasive method for generating abundance estimates of terrapin populations across broader spatial scales than has been achieved using capture–recapture, and can be used to quantify determinants of spatial variation in abundance. We conducted repeated visual head count surveys along the shoreline of Wellfleet Bay in Wellfleet, Massachusetts, and analyzed the count data using a hierarchical modeling framework designed specifically for repeated count data: the N-mixture model. This approach allows for simultaneous modeling of imperfect detection to generate estimates of true terrapin abundance. Detection probability was lowest when temperatures were coldest and when wind speed was highest. Local abundance was on average higher in sheltered sites compared to exposed sites and declined over the course of the sampling season. We demonstrate the utility of pairing visual head counts and N-mixture models as an efficient method for estimating terrapin abundance and show how the approach can be used to identifying environmental factors that influence detectability and distribution. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
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17 pages, 2634 KiB  
Article
A Comparison of the Population Genetic Structure and Diversity between a Common (Chrysemys p. picta) and an Endangered (Clemmys guttata) Freshwater Turtle
by Scott W. Buchanan, Jason J. Kolbe, Johanna E. Wegener, Jessica R. Atutubo and Nancy E. Karraker
Diversity 2019, 11(7), 99; https://0-doi-org.brum.beds.ac.uk/10.3390/d11070099 - 26 Jun 2019
Cited by 8 | Viewed by 4870
Abstract
The northeastern United States has experienced dramatic alteration to its landscape since the time of European settlement. This alteration has had major impacts on the distribution and abundance of wildlife populations, but the legacy of this landscape change remains largely unexplored for most [...] Read more.
The northeastern United States has experienced dramatic alteration to its landscape since the time of European settlement. This alteration has had major impacts on the distribution and abundance of wildlife populations, but the legacy of this landscape change remains largely unexplored for most species of freshwater turtles. We used microsatellite markers to characterize and compare the population genetic structure and diversity between an abundant generalist, the eastern painted turtle (Chrysemys p. picta), and the rare, more specialized, spotted turtle (Clemmys guttata) in Rhode Island, USA. We predicted that because spotted turtles have disproportionately experienced the detrimental effects of habitat loss and fragmentation associated with landscape change, that these effects would manifest in the form of higher inbreeding, less diversity, and greater population genetic structure compared to eastern painted turtles. As expected, eastern painted turtles exhibited little population genetic structure, showed no evidence of inbreeding, and little differentiation among sampling sites. For spotted turtles, however, results were consistent with certain predictions and inconsistent with others. We found evidence of modest inbreeding, as well as tentative evidence of recent population declines. However, genetic diversity and differentiation among sites were comparable between species. As our results do not suggest any major signals of genetic degradation in spotted turtles, the southern region of Rhode Island may serve as a regional conservation reserve network, where the maintenance of population viability and connectivity should be prioritized. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
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12 pages, 2870 KiB  
Article
Long-Term Variation in Survival of A Neotropical Freshwater Turtle: Habitat and Climatic Influences
by Mario F. Garcés-Restrepo, John L. Carr and Alan Giraldo
Diversity 2019, 11(6), 97; https://0-doi-org.brum.beds.ac.uk/10.3390/d11060097 - 20 Jun 2019
Cited by 8 | Viewed by 3099
Abstract
Few long-term demographic studies have been conducted on freshwater turtles of South America, despite the need for this type of inquiry to investigate natural variation and strengthen conservation efforts for these species. In this study, we examined the variation in demography of the [...] Read more.
Few long-term demographic studies have been conducted on freshwater turtles of South America, despite the need for this type of inquiry to investigate natural variation and strengthen conservation efforts for these species. In this study, we examined the variation in demography of the Chocoan River Turtle (Rhinoclemmys nasuta) based on a population from an island locality in the Colombian Pacific region between 2005 and 2017. We calculated survival, recapture, and transition probabilities, and the effects of stream substrate and El Niño–Southern Oscillation (ENSO) phases (El Niño, Neutral, La Niña) on these variables using a multi-state model. We found differences in survival probabilities between ENSO phases, likely as a consequence of an increase in flood events. In addition, we found support for survival being greater in muddy streams than rocky streams, possibly because it is easier to escape or hide in mud substrates. Recapture probabilities varied by life stages; differences in the probability of recapture between size classes were associated with the high fidelity to territories by adults. The present increases in frequency and severity of El Niño and La Niña may exacerbate the consequences of climatic regimes on natural populations of turtles by increasing the mortality caused by drastic phenomena such as floods. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
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14 pages, 2353 KiB  
Article
Do Local Environmental Factors and Lunar Cycle Influence Timing and Synchrony of Oviposition of a Turtle with Strict Nocturnal Nesting?
by Tibisay Escalona, Nicole Valenzuela and Dean C. Adams
Diversity 2019, 11(5), 78; https://0-doi-org.brum.beds.ac.uk/10.3390/d11050078 - 15 May 2019
Cited by 8 | Viewed by 4396
Abstract
Timing of nesting affects fitness of oviparous animals living in seasonal environments, and females may cue on environmental factors for their nesting behavior, but these relationships are understudied in tropical turtles. Here, the timing and synchrony of egg-laying relative to environmental factors were [...] Read more.
Timing of nesting affects fitness of oviparous animals living in seasonal environments, and females may cue on environmental factors for their nesting behavior, but these relationships are understudied in tropical turtles. Here, the timing and synchrony of egg-laying relative to environmental factors were examined in the South American freshwater turtle Podocnemis unifilis on 11 nesting beaches during three nesting seasons. Daily measurements included number of nests laid, rainfall, river level, air temperature, and the phase of the lunar cycle (full moon, last quarter, new moon and first quarter). Results confirmed that P. unifilis nested at night and revealed that females in our population nest in groups from 2 to 17 females at a time. Nesting was not correlated with rainfall, but a significant relationship was found with river level, such that nesting started at the onset of the dry season when river levels dropped and nesting grounds emerged. Importantly, we found that (1) nesting events concentrated on days with intermediate daily maximum air temperature (although maxima changed annually), and that (2) larger groups of females nested around full moon, suggesting the reliance on visual cues to initiate nesting activities (consistent with social facilitation behavior). Altogether, the timing of nesting in P. unifilis may be shaped by a combination of environmental factors, moon phase and social facilitation, where visual cues play an important role. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
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11 pages, 1219 KiB  
Article
Evaluation of Gonadal Tissue to Validate Size at Reproductive Maturity in Kemp’s Ridley Sea Turtles Found Stranded in Texas, USA
by Kathryn Stephenson Craven, Jay York Seabright Hodgson, Donna Jill Shaver, Jennifer Shelby Walker, Martha Ramona Villalba-Guerra and David William Owens
Diversity 2019, 11(5), 76; https://0-doi-org.brum.beds.ac.uk/10.3390/d11050076 - 09 May 2019
Cited by 5 | Viewed by 3123
Abstract
The Kemp’s ridley, Lepidochelys kempii, is the most endangered sea turtle in the world. Anthropogenic mortality of Kemp’s ridleys has been well documented in the Gulf of Mexico (GOM), USA. We evaluated the reproductive maturity of 75 Kemp’s ridley sea turtles found [...] Read more.
The Kemp’s ridley, Lepidochelys kempii, is the most endangered sea turtle in the world. Anthropogenic mortality of Kemp’s ridleys has been well documented in the Gulf of Mexico (GOM), USA. We evaluated the reproductive maturity of 75 Kemp’s ridley sea turtles found dead on GOM beaches on Mustang Island and North Padre Island, Texas, USA, 1994–1999. Straight carapace length (SCL) ranged from 40.8 to 68.7 cm. Preserved gonads and associated tissues were examined and measured. Gonadal measurements were then compared with SCL. Adults and juveniles shared a larger range of carapace measurements than expected, supporting the idea that juveniles spend several years in a pubertal state. Our results suggest caution when using SCL, tail length, or curved front claws alone as indicators of sexual maturity. In fact, SCL can be used to discern adults from juveniles with more predictive power when coupled with testis length or oviduct length measurements, thus allowing endangered species managers to more clearly identify demographic shifts in the number of mature animals, which can precede population changes. This study shows that information gained from the examination of stranded sea turtles allows wildlife managers to make more informed decisions regarding conservation priorities. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
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13 pages, 3333 KiB  
Article
Assessing the Impacts of Urbanization on Sex Ratios of Painted Turtles (Chrysemys picta)
by John P. Vanek and Gary A. Glowacki
Diversity 2019, 11(5), 72; https://0-doi-org.brum.beds.ac.uk/10.3390/d11050072 - 02 May 2019
Cited by 17 | Viewed by 4882
Abstract
Turtles are particularly susceptible to the negative impacts of urbanization due to low mobility and a life history strategy emphasizing long generation times and high adult survival. In addition to declines directly through habitat loss, urbanization has been hypothesized to limit populations of [...] Read more.
Turtles are particularly susceptible to the negative impacts of urbanization due to low mobility and a life history strategy emphasizing long generation times and high adult survival. In addition to declines directly through habitat loss, urbanization has been hypothesized to limit populations of aquatic turtles through changes in population structure, as adult females are disproportionally killed on and near roads, leading to male-biased populations, which can lead to population declines or local extirpations. The purpose of this study was to better understand how urbanization impacts the sex ratios of painted turtles (Chrysemys picta) in an urban ecosystem, as empirical results linking male-biased turtle populations to roads and urbanization are mixed. Using eight years of trapping data from a long-term monitoring program in a suburb of Chicago, IL, USA, we report one of the most male-biased populations ( x ¯ = 75% male) of turtles in the USA, consistent with prevailing road mortality hypotheses. However, we found no evidence that male-biased populations were related to road density or the amount of protected area around a sampling location and found that impervious surface (a metric of urbanization) was weakly related to less male-biased populations. Our results highlight the importance of replicating ecological studies across space and time and the difficulty in assessing population structure in aquatic turtles. We suggest that active conservation measures may be warranted for the continued persistence of urban turtle populations. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
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12 pages, 883 KiB  
Article
A Surfeit of Studies: What Have We Learned from All the Box Turtle (Terrapene carolina and T. ornata) Home Range Studies?
by Christopher W. Habeck, Miranda P. Figueras, Jean E. Deo and Russell L. Burke
Diversity 2019, 11(5), 68; https://0-doi-org.brum.beds.ac.uk/10.3390/d11050068 - 28 Apr 2019
Cited by 13 | Viewed by 4436
Abstract
Home range (HR) studies are a particularly common approach to investigations of animal habitat use, resource availability, and response to management manipulation such as relocations. Terrapene carolina (Eastern box turtle) and its sister taxon T. ornata (Ornate box turtle) are especially popular subjects [...] Read more.
Home range (HR) studies are a particularly common approach to investigations of animal habitat use, resource availability, and response to management manipulation such as relocations. Terrapene carolina (Eastern box turtle) and its sister taxon T. ornata (Ornate box turtle) are especially popular subjects of HR studies because they are relatively easily tracked. Terrapene HR studies have revealed a wide variation in HR sizes within and between populations, due to factors such as differences in ecoregion and analytical approach (e.g., minimum convex polygons, kernel analysis, bivariate normal, multivariate Ornstein–Uhlenbeck stochastic process, harmonic means). We performed a meta-analysis of the available literature, including unpublished work to avoid bias due to under-publication, to explore the causes for variation in HR size. We found 19 studies reporting T. carolina HR sizes and seven studies reporting T. ornata HR sizes; the resulting meta-analysis revealed patterns that are not visible in the individual studies. We found important differences between the species: female T. ornata had smaller HRs than males, whereas the opposite is true for T. carolina, and T. ornata HRs were influenced by ecoregion, while T. carolina HRs were not similarly influenced. Not surprisingly, we found that choice of analysis technique affected HR estimate; analyses using ellipses resulted in larger HR estimates than all the other techniques, while kernels were smaller than minimum convex polygons. Although not indicated by individual studies, our meta-analysis showed that the HRs of relocated T. carolina females were significantly larger than those of non-relocated females. Although the number of individual turtles in studies varied from three to 25, the sample size did not significantly affect HR size. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
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22 pages, 1215 KiB  
Article
A Brief Review of Non-Avian Reptile Environmental DNA (eDNA), with a Case Study of Painted Turtle (Chrysemys picta) eDNA Under Field Conditions
by Clare I. M. Adams, Luke A. Hoekstra, Morgan R. Muell and Fredric J. Janzen
Diversity 2019, 11(4), 50; https://0-doi-org.brum.beds.ac.uk/10.3390/d11040050 - 29 Mar 2019
Cited by 38 | Viewed by 9660
Abstract
Environmental DNA (eDNA) is an increasingly used non-invasive molecular tool for detecting species presence and monitoring populations. In this article, we review the current state of non-avian reptile eDNA work in aquatic systems, and present a field experiment on detecting the presence of [...] Read more.
Environmental DNA (eDNA) is an increasingly used non-invasive molecular tool for detecting species presence and monitoring populations. In this article, we review the current state of non-avian reptile eDNA work in aquatic systems, and present a field experiment on detecting the presence of painted turtle (Chrysemys picta) eDNA. Thus far, turtle and snake eDNA studies have shown mixed results in detecting the presence of these animals under field conditions. However, some instances of low detection rates and non-detection occur for these non-avian reptiles, especially for squamates. We explored non-avian reptile eDNA quantification by sampling four lentic ponds with different densities (0 kg/ha, 6 kg/ha, 9 kg/ha, and 13 kg/ha) of painted turtles over three months to detect differences in eDNA using a qPCR assay amplifying the COI gene of the mtDNA genome. Only one sample of the highest-density pond amplified eDNA for a positive detection. Yet, estimates of eDNA concentration from pond eDNA were rank-order correlated with turtle density. We present the “shedding hypothesis”—the possibility that animals with hard, keratinized integument do not shed as much DNA as mucus-covered organisms—as a potential challenge for eDNA studies. Despite challenges with eDNA inhibition and availability in water samples, we remain hopeful that eDNA can be used to detect freshwater turtles in the field. We provide key recommendations for biologists wishing to use eDNA methods for detecting non-avian reptiles. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
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12 pages, 1774 KiB  
Article
Tradeoffs with Growth and Behavior for Captive Box Turtles Head-Started with Environmental Enrichment
by Sasha J. Tetzlaff, Jinelle H. Sperry and Brett A. DeGregorio
Diversity 2019, 11(3), 40; https://0-doi-org.brum.beds.ac.uk/10.3390/d11030040 - 07 Mar 2019
Cited by 14 | Viewed by 7145
Abstract
Head-starting is a conservation strategy that entails releasing captive-reared animals into nature at sizes large enough to better resist post-release predation. However, efforts to maximize growth in captivity may jeopardize development of beneficial behaviors. Environmental enrichment can encourage natural behaviors before release but [...] Read more.
Head-starting is a conservation strategy that entails releasing captive-reared animals into nature at sizes large enough to better resist post-release predation. However, efforts to maximize growth in captivity may jeopardize development of beneficial behaviors. Environmental enrichment can encourage natural behaviors before release but potentially comes with a tradeoff of reduced growth in complex enclosures. We compared growth and behavior of enriched and unenriched captive-born juvenile box turtles (Terrapene carolina). Enriched turtles grew slower than unenriched turtles during the first eight months in captivity, although growth rates did not differ between treatments from 9–20 months old. After five months post-hatching, unenriched turtles became and remained larger overall than enriched turtles. During two foraging tasks, unenriched turtles consumed more novel prey than enriched turtles. In a predator recognition test, eight-month-old enriched turtles avoided raccoon (Procyon lotor) urine more than unenriched turtles of the same age, but this difference was not apparent one year later. The odds of turtles emerging from a shelter did not differ between treatments regardless of age. Although our results suggest turtles raised in unenriched environments initially grew faster and obtained larger overall sizes than those in enriched conditions, tradeoffs with ecologically-relevant behaviors were either absent or conditional. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
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16 pages, 1669 KiB  
Article
GPS Technology for Semi-Aquatic Turtle Research
by Madaline M. Cochrane, Donald J. Brown and Ron A. Moen
Diversity 2019, 11(3), 34; https://0-doi-org.brum.beds.ac.uk/10.3390/d11030034 - 01 Mar 2019
Cited by 6 | Viewed by 4559
Abstract
Global positioning system (GPS) telemetry units are now small enough to be deployed on terrestrial and semi-aquatic turtles. Many of these GPS units use snapshot technology which collects raw satellite and timestamp data during brief periods of data recording to minimize size. We [...] Read more.
Global positioning system (GPS) telemetry units are now small enough to be deployed on terrestrial and semi-aquatic turtles. Many of these GPS units use snapshot technology which collects raw satellite and timestamp data during brief periods of data recording to minimize size. We evaluated locations from snapshot GPS units in stationary tests and on wood turtles (Glyptemys insculpta) in northeastern Minnesota. Stationary GPS units were placed in wood turtle habitat to evaluate location accuracy, fix success rate, and directional bias. The GPS fix success rate and accuracy were reduced in closed canopy conditions and when the stationary GPS unit was placed under a log to simulate wood turtle hiding behavior. We removed GPS location outliers and used a moving average calculation to reduce mean location error in stationary tests from 27 m (SD = 38) to 10 m (SD = 8). We then deployed GPS units and temperature loggers on wood turtles and collected 122,657 GPS locations and 242,781 temperature readings from 26 turtles from May to September 2015 and 2016. Location outliers accounted for 12% of locations when the GPS receiver was on a turtle. We classified each wood turtle location based on the GPS location and by comparing temperature profiles from river, sun, and shaded locations to the temperature logger on the turtle. We estimated that wood turtles were on land 68% (SD = 12) of the time from May to September. The fix success rate for land locations was 38% (SD = 9), indicating that wood turtles often use habitats with obstructed views of the sky. Mean net daily movement was 55 m (SD = 192). Our results demonstrate that snapshot GPS units and temperature loggers provide fine-scale GPS data useful in describing spatial ecology and habitat use of semi-aquatic turtles. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
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Review

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22 pages, 509 KiB  
Review
A Review of the Effects of Climate Change on Chelonians
by Christopher J. Butler
Diversity 2019, 11(8), 138; https://0-doi-org.brum.beds.ac.uk/10.3390/d11080138 - 16 Aug 2019
Cited by 31 | Viewed by 10727
Abstract
Climate change is occurring at an unprecedented rate and has begun to modify the distribution and phenology of organisms worldwide. Chelonians are expected to be particularly vulnerable due to limited dispersal capabilities as well as widespread temperature-dependent sex determination. The number of papers [...] Read more.
Climate change is occurring at an unprecedented rate and has begun to modify the distribution and phenology of organisms worldwide. Chelonians are expected to be particularly vulnerable due to limited dispersal capabilities as well as widespread temperature-dependent sex determination. The number of papers published about the effects of climate change on turtles has increased exponentially over the last decade; here, I review the data from peer-reviewed publications to assess the likely impacts of climate change on individuals, populations, and communities. Based upon these studies future research should focus on: (1) Individual responses to climate change, particularly with respect to thermal biology, phenology, and microhabitat selection; (2) improving species distribution models by incorporating fine-scale environmental variables as well as physiological processes; (3) identifying the consequences of skewed sex ratios; and (4) assessments of community resilience and the development of methods to mitigate climate change impacts. Although detailed management recommendations are not possible at this point, careful consideration should be given regarding how to manage low vagility species as habitats shift poleward. In the worst-case scenario, proactive management may be required in order to ensure that widespread losses do not occur. Full article
(This article belongs to the Special Issue Advances in the Biology and Conservation of Turtles)
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