Ecology and Conservation of Freshwater Turtles

Symposium
ROOM: HCCC, Room 25C
SESSION NUMBER: 32
 
Freshwater turtles are one of the most threatened taxa worldwide, with 10% of all species recognized as critically endangered and 42% considered threatened. The southeastern United States and Great Lakes region of North America are epicenters for freshwater turtle diversity and of global importance for turtle conservation. Given the importance of multiple ecoregions in the United States for maintaining freshwater turtle diversity, understanding threats and potential mitigative actions is imperative for guiding conservation and monitoring efforts. This symposium addresses primary threats to freshwater turtle populations including climate change, habitat destruction, and fragmentation as well as potential mitigative actions. Presentations in this symposium will address conservation and management concerns around freshwater turtles, but the lessons learned from turtles can be applied to many other organisms.

8:10AM What Science, Long-Term Studies, Conservation Concepts, and Myths Bring to Interactions Among Stake Holders?
  Justin D. Congdon
9:10AM Are Turtles Suitable Indicators of Habitat Health and Proper Management?
  Whit Gibbons
Turtles can endure almost any affront the natural world has to offer. But they have not done so well with the disrespectful behavior of humans. Turtles (which of course include tortoises and sea turtles) have declined dramatically at the hands of unscrupulous pet trade merchants, food market barons, and look-the-other-way government officials resulting in the removal of staggering numbers from natural habitats worldwide. Ironically, turtles are not necessarily the front-line indicators of habitat health because of their resilience, hardiness, and endurance in the face of extraordinary habitat changes. Support for the premise that humans are the biggest problem turtles have, but not necessarily from habitat degradation, will be given by examples from studies demonstrating that turtles can survive impressive environmental modifications. Thus, when the turtles are not faring well, it is an indicator that the rest of the ecosystem is already in bad shape. By the time turtles are in trouble due to habitat health, the concept of proper habitat management is an issue for academic discussions during cocktail hour, because the time has past for prudent conservation measures. Maybe we can get ready for the next assault.
09:50AM Break
12:50PM Climate Change and Temperature Dependent Sex Determination
  Fredric J. Janzen
Numerous anthropogenic processes increasingly imperil turtles globally. Now, rapid climate change stands to exacerbate these problems, since so many of these species also have temperature-dependent sex determination (TSD). Can these iconic, long-lived animals adapt fast enough to match ongoing climate change or will they fail by evolving at a turtle’s pace instead? To illuminate this pressing matter, I will present findings obtained from over a quarter century of collaborative study of populations of painted turtles (Chrysemys picta) with TSD. I will first illustrate the considerable sensitivity of offspring cohort sex ratios to annual variation in climatic temperatures and then report on quantitative genetic analyses of three key traits that could permit TSD in these populations to adapt to biased offspring sex ratios expected under a moderate projection of climate change by the year 2100. The results of this extensive research indicate moderate among-year repeatabilities, but small overall field heritabilities, for (1) thermal sensitivity of embryonic sex determination, (2) nest-site choice with respect to vegetation cover, and (3) nesting phenology (=onset of the nesting season). Consequently, the potential for microevolution of TSD to keep pace with expected climate change appears to be limited. I will discuss the implications of these findings in terms of possible conservation and management actions.
1:10PM Roads and the Conservation of Freshwater Turtles
  David A. Steen
Based on what we know about freshwater turtle population demography, the mortality of adults on the road should be of general conservation concern for this group of animals. Since 2004, I have worked with a number of collaborators to determine how roads were influencing freshwater turtle populations, identify the scope of the problem, and then propose solutions based on how these animals use the terrestrial landscape. Our work demonstrated that A) female turtles were more vulnerable than males due to their requisite nesting migrations B) wetlands surrounded by a high density of roads contained male-biased populations presumably due to disproportionate mortality of females and C) this trend was widespread across the continent and apparently becoming increasingly severe. Because the root of this problem was females getting killed on nesting migrations, we conducted a comprehensive effort to assess the spatial extent of these movements. Ideally, this information may be useful to land managers interested in road placement, design, and mitigation. I will conclude by discussing some related questions we have yet to fully resolve and suggest future lines of research and conservation that may allow us to continue to use the landscape alongside large populations of freshwater turtles.
1:30PM Mapping and Identifying Critical Habitat for At-Risk Reptiles: Importance of Hydrologic Setting
  Chantel E. Markle; James M. Waddington
Reptiles occurring in Ontario, Canada exist at the northern limit of their species’ range and are vulnerable to climate change, land-use changes, and increased human presence. To better understand how sensitive reptile species may respond to such stressors, habitat suitability and occupancy models can be used to predict the distribution of important habitats under different scenarios, identify critical landscape features which contribute to habitat resilience, and guide management plans. Here, we used a landscape-scale database to investigate the effect of anthropogenic development, land cover class, and hydrologic setting on wetland suitability and occupancy for at-risk turtles. In total, 415 individual wetlands were surveyed for at-risk reptiles between 2013 and 2017 across the rock barren landscape of Georgian Bay, Lake Huron, Ontario. We hypothesized that the degree of aquatic connectivity in the surrounding upland matrix and the spatial complexity of wetland vegetation cover were important factors contributing to wetland occupancy by at-risk turtles. Furthermore, we explored the link between stage of peatland succession and reptile occupancy. We use a combination of habitat suitability and occupancy modeling techniques to identify key landscape features dictating reptile distribution patterns. Of the 415 surveyed wetlands, just over 55% were occupied by at-risk turtles. Preliminary results indicate that the spatial complexity and distribution of surface vegetation cover is an important distinguishing feature among wetlands supporting different reptile species-at-risk. Our resulting models can be used to predict the effects of climate change and altered landscape connectivity on wetland occupancy and suitability, and provide valuable insights to guide wetland restoration strategies.
1:50PM Making Road Networks Less Unfriendly to Turtles: From Planning to Mitigation
  Tom A. Langen
Road-kill and connectivity blockages caused by roads and road traffic can result in serious population declines of turtles. Turtles are particularly vulnerable to population declines caused by excessive road-kill because of their demography and because it is predominately breeding females that are killed on roads. Landscape-scale modeling of road mortality risk and road-caused habitat fragmentation indicate that effective monitoring and mitigation of these impacts on turtles require attention to the entire regional road network. I will explain general methods by which road-kill hotspots and connectivity blockages caused by roads can be predicted throughout a road network by creation and use of predictive models. Once such critical road segments for mitigation have been located, what is to be done? Wildlife fences designed for turtles may be an effective and relatively inexpensive mitigation measure to conserve aquatic turtle populations within a roaded landscape. I report on the design, cost, durability, and effectiveness of wildlife barriers along state highways that are intended to prevent turtle trespass onto roads in the northeastern US, and the effectiveness of culverts as passage structures. I conclude that for turtles optimal locations for mitigation within a road network can be predicted, and relatively inexpensive and easy-to-install fencing can be effective at reducing aquatic turtle road-kill, but some post-installation monitoring can indicate design modifications to improve effectiveness, and occasional inspection and repair is necessary to insure long-term functioning. There are viable options for natural resource and transportation agencies to reduce the negative impacts that roads and road traffic have on turtles.
2:10PM Empirically Assessing Headstarting as a Conservation Tool for Freshwater Turtles
  Willem M. Roosenburg; David Jenkins; Nicholas A. Smeenk; Converse Paul; Alayna Tokash
We conducted an empirical evaluation of headstarting as a supplementation tool in a population of the diamond-backed terrapin, Malaclemys terrapin. Our objective was to determine the effect of headstarting on the population growth rate, λ and other life history parameters. From 2005 – 2017, we released over 2,300 headstarted individuals and almost 14,000 natural emergence hatchlings (NEH) on the Paul S. Sarbanes Ecosystem Restoration Project on Poplar Island, Maryland. All headstarts were collected from natural nests, headstarted for eight months throughout Maryland schools, PIT tagged and released on Poplar Island in the spring of year one. All NEHs were tagged with binary coded wire and cohort scute notching and released within 24 hours of emergence. We used mark-recapture to relocate both groups and upon recapture, all NEHs and unmarked individuals were PIT tagged. We used R-MARK to estimate survival parameters and λ for the combined populations and compared headstarts vs. natural emergence hatchlings. We find early survival to be higher in headstarts and comparable survival in later stage classes to NEHs. Furthermore, several headstarts carried oviducal eggs as determined through inguinal palpation at age 6 compared to the youngest NEH at year 7. Finally, we find no difference between the average size of hatchlings released and the mean size at time of release of those that were recaptured. We find that headstarting can be an effective tool to supplement populations to increase λ. However, we caution about the constraints of demographic stochasticity and warn that headstarting remains a “halfway technology” that only addresses the symptom of population decline and not the causes.
2:30PM Refreshment Break
3:20PM The Importance of Health and Veterinary Care in Freshwater Turtle Conservation
  Michael B. Selig
It is estimated that over 50% of turtles are threatened and as a group are considered one of the most endangered taxonomic groups. Pressures such as habitat loss, over collection, road mortality, and diseases are all contributing to this decline. Determining a population’s health by assessing presence or absence is no longer enough. We have an ever-growing ability to evaluate individual diseases, genetic relatedness, and ecological changes. However, determining what is considered “healthy” has become an increasingly difficult question. A thorough evaluation of all the interconnecting risk factors affecting a population is necessary. Due to the challenges associated with making these population assessmentsit is imperative that a collaborative approach be taken.
3:40PM Conservation Implications of Being a Habitat Generalist and a Seasonal Activity Specialist: A Case Study Using Spotted Turtles
  Jacqueline D. Litzgus
The more I study Spotted Turtles (Clemmys guttata), the more I realize that there is still much to learn about this Species at Risk. My students and I have been studying and visiting various populations in Canada and the USA for more than 25 years, and I am frequently amazed by the differences in ecology among sites. Based on our observations, I was recently struck by two facts regarding Spotted Turtle habitat and activity patterns: on a global scale, the species is a habitat generalist, but at the local scale, individual populations are specialists in terms of their activity cycles. Across the North American range, we have found populations in cypress-tupelo swamp forests, alder swamps, sphagnum and fern swamps, open-canopy fens, bogs, flowing streams, stagnant beaver ponds, man-made ditches, and even small pools on rocky islands. Given such diversity, how does one quantify or predict the species’ habitat preference? Locally, Spotted Turtles display predictable seasonal shifts in activity and habitat use, and show temporal fidelity to specific sites. These activity patterns vary geographically among populations with earlier activity peaks in the south, and longer hibernation and shorter nesting seasons in the north. Protection of endangered species requires description of critical habitats, and this generalist-and-specialist dichotomy in Spotted Turtles presents an obvious challenge for creating and implementing conservation plans that focus on habitat protection. The data suggest that each population must be treated separately in assessments of critical habitat and seasonal activity, which in turn can present financial and logistical obstacles for management agencies. These obstacles must be overcome because, clearly, both site-specific and range-wide ecological data are essential for recovery strategies that aim to maintain the global population of Spotted Turtles.
4:00PM Spotted Turtle Movement and Occupancy Dynamics Across an Urbanized Landscape
  Ellery V. Ruther
Wetland ecosystems are often both spatially and temporally variable, causing wildlife to utilize several different wetlands across a season, and therefore characteristics such as wetland quality and connectivity are likely to influence demographic processes. The ecology of semi-aquatic freshwater turtles makes them especially vulnerable to habitat fragmentation, because individuals often make long distance movements among a variety of habitats for mating, foraging, aestivating, and overwintering purposes. I investigated the movement patterns and occupancy dynamics of the spotted turtle (Clemmys guttata) in a highly urbanized landscape in northern Virginia. I radio-located 30 adult and 10 juvenile turtles across the active season (March-August) in 2017 and 2018. I used daily movements and home range sizes (autocorrelated kernel density estimates) as response variables in generalized linear mixed models and tested for effects of sex, age, climatic, and landscape features, as well as interactions among these. I also examined the occupancy dynamics of wetland patches using the same covariates. Juvenile turtles exhibited smaller daily movement and home range sizes than adult turtles. Turtle movement was strongly associated with precipitation and wetland depth, and home range size had an inverse relationship with road density. Road crossing frequency was correlated with precipitation, with no apparent influence from age or sex class. Variation in occupancy probability was best explained by climatic covariates, rather than habitat quality. This may be a function of the limited wetland availability, therefore forcing turtles to occupy sub-optimal patches. Because spotted turtles are equally dependent on both aquatic and terrestrial habitats, and may make large movements between wetland patches, it is recommended that this species should be managed using a landscape conservation approach. Further, conservation of wetland matrices and the connectivity among them, rather than individual patches, is vital for the population stability of this species and other sympatric semi-aquatic wildlife.
4:20PM Collaborative Conservation for Blanding’s Turtles in the Northeastern United States
  Lisabeth L. Willey; Michael T. Jones; Michael Marchand; Paul R. Sievert
Blanding’s turtles (Emydoidea blandingii) are listed as Endangered by the IUCN and were identified as a species of high regional responsibility by Northeast Partners for Amphibian and Reptile Conservation. The Northeast Blanding’s Turtle Working Group (NEBTWG: www.blandingsturtle.org), a collaborative group of state and federal agencies, non-profits, universities, and independent biologists, has been working since 2004 to conserve the Blanding’s turtles throughout their range in the northeastern US, including portions of Maine, New Hampshire, Massachusetts, New York, and Pennsylvania, where they occur in disjunct populations. Following a regional status assessment in 2007, with support from a Competitive State Wildlife Grant, the NEBTWG developed a Conservation Plan in 2014. As part of the planning process, we undertook standardized monitoring to establish baseline distribution and abundance in order to track change over time, rank and prioritize sites, assess the effects of habitat and landscape characteristics on population size and structure, and identify covariates that influence detection. The monitoring strategy has two, nested tiers: intensively trapped sites that provide site-specific population estimates using mark-recapture models and rapid assessment sites that are analyzed using mixture models. Across the Northeast during 2012—2013, we captured 1,178 Blanding’s turtles (including recaptures) at 156 sites over 20,342 trap nights. The Conservation Plan incorporated empirical data, genetic information, and habitat and population models to identify priority sites and actions. We are currently implementing the highest priority actions identified in the Plan including land protection, habitat management and restoration, and head-starting and nest protection. We are also continuing standardized sampling, which will be used to evaluate the effectiveness of actions and to adaptively modify the conservation strategy going forward. Several efforts for related species have been modeled after this effort, including Wood Turtles in the Northeast, and an effort just beginning for Spotted Turtles from Maine to Florida.
4:40PM Conservation Plan for the Wood Turtle in the Northeastern United States
  Michael T. Jones; Patrick Roberts; Lisabeth Willey; Thomas Akre; Paul Sievert; Dana Weigel; Andrew Whiteley
The Wood Turtle (Glyptemys insculpta) is listed as Endangered by the IUCN and is a Regional Species of Greatest Conservation Need in the northeastern United States, where many populations have declined. In 2018, the Northeastern State Wildlife Agencies from Maine to Virginia completed a Conservation Plan for the Wood Turtle in the Northeast, supported by a Competitive State Wildlife Grant and the Northeast Regional Conservation Needs (RCN) program. The Northeast Wood Turtle Conservation Plan is composed of six elements: (1) a five-year, standardized, hierarchical population assessment in all northeastern States to identify robust and regionally significant populations and to establish baselines, for which nearly 400 surveyors participated in a total of 2,141 field surveys throughout the Northeast and recorded 4,611 Wood Turtle detections; (2) an analysis of regional population genetics to evaluate genetic diversity and relatedness as well as the feasibility of genetic assignment of confiscated Wood Turtles, for which 1,895 individual turtles were analyzed; (3) the development of habitat management guidelines and technical assistance materials for key landowners, and a rangewide conservation symposium for the species held in Massachusetts; (4) a spatially-explicit, geographically stratified Conservation Area Network built from empirical population data, distribution data, predictive habitat and distribution models, patterns of population genetics, and an expert-weighted algorithm; (5) a spatially-explicit and expert-informed Conservation Action Plan for priority sites; (6) a multi-scale implementation framework modeled upon other regional conservation planning efforts including those for Blanding’s Turtle. We used pseudonyms throughout the process to protect sensitive site locations. Critical actions are primarily geared toward the protection and appropriate management of high-integrity riparian habitats. Key aspects of the Plan’s implementation and effectiveness monitoring will be funded by the RCN program and managed by the Wood Turtle Council, a formal Working Group made up of state agencies and partners.

 
Organizers: Nicholas Smeenk, The Ohio State University, Columbus, OH; Greg Lipps, The Ohio State University, Columbus, OH; Matt Cross, Toledo Zoo, Toledo, OH; Mike Benard, Case Western Reserve University, Cleveland, OH; Mark Jordan, Purdue University – Ft. Wayne, Ft. Wayne, IN; Teal Richards-Dimitrie, EnviroScience Inc., Stow, OH; David Dimitrie, Case Western Reserve University, Cleveland, OH
 
Supported by: Ohio Partners in Amphibian and Reptile Conservation; Midwest Partners in Amphibian and Reptile Conservation

Symposium
Location: Huntington Convention Center of Cleveland Date: October 9, 2018 Time: 8:10 am - 5:00 pm