Session 43: Turtle Conservation & ManagementRoom: Room 206C2022-07-31 08:15 - 09:15 |
| Moderator: Gareth Hopkins |
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1. 08:15 Effects of Human Land Use and Landscape Context on Population Demographics of the Painted Turtle (Chrysemys picta). Benjamin Phillips*, University of New Hampshire; Remmington Moll, University of New Hampshire; Rebecca Rowe, University of New Hampshire; Jennifer Purrenhage, University of New Hampshire benjamin.phillips@unh.edu
Habitat loss and fragmentation can negatively affect freshwater turtle populations through local and landscape factors that influence sex ratio and survival. Population sex ratios can become skewed due to changes in temperature, exposure to endocrine disrupting pollutants, and female-biased mortality. Human development often removes vegetative cover which increases ground temperatures resulting in a higher proportion of female hatchlings. Many forms of land use also lead to chemical contamination of surface waters, and exposure to certain endocrine-disrupting chemicals may either compound or mask temperature-mediated effects on sex ratios in aquatic species. Additionally, female turtles are disproportionately susceptible to direct mortality from vehicle collision and predators due to their annual nesting migrations. The goal of this study was to assess how land cover and land use influence freshwater turtle abundance and population dynamics in southeastern New Hampshire. This study focused exclusively on the painted turtle (Chrysemys picta) because they are common, and their relatively short generation time suggests they will show a measurable response to disturbance before other turtle species. We sampled 31 ponds along a gradient of urbanization to estimate sex ratio and population size. We used a Bayesian mixed model analysis to assess the relative importance of land cover and road density on abundance and sex ratio. We also assessed presence of common industrial, agricultural, and pharmaceutical pollutants in pond water and turtle blood. Our findings provide insights into the impacts of land use and land cover on the population dynamics of freshwater turtles. |
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2. 08:30 Responses of Native and Invasive Freshwater Turtles to Basking and Nesting Habitat Restoration in the Pacific Northwest. Gareth Hopkins*, Western Oregon University; Stephani Symanowicz, Western Oregon University; Emil Ricci, Western Oregon University; Summer Broome, Western Oregon University; Matthew Johnston, City of Salem; Susan Barnes, Oregon Department of Fish & Wildlife; Jennifer Ringo, Oregon Department of Fish & Wildlife hopkinsg@mail.wou.edu
The Pacific Northwest’s native freshwater turtles, the Western Painted Turtle (Chrysemys picta) and the Northwestern Pond Turtle (Actinemys marmorta), are listed as species of conservation concern due to habitat loss, human activity, and interactions with invasive species (e.g., bullfrogs; invasive plants; and Red-eared Sliders (Trachemys scripta)). As such, habitat restoration is a critical tool for the conservation of these species. How native and invasive turtles respond to restoration is not well quantified. We investigated how turtles responded to restoration of basking and nesting habitat in a semi-urban park in the City of Salem, Oregon. Supplemental basking structures were added to waterbodies, and the use of these structures by native and invasive turtles was monitored. Structure use was examined in the context of location within a waterbody, temperature, and structure type. We also restored nesting habitat in some areas through removal of invasive blackberries, restricting human activity, and introduction of dirt mounds to improve substrate. We monitored nesting activity and quantified abiotic habitat characteristics of all detected nests in order to understand if environmental factors might predict nesting. We found species-specific basking structure use, with supplemental platforms being highly used by native turtles, but in a more restricted temperature range, compared to sliders. In contrast, a very low number of successful nests of any species was detected. There were significant abiotic predictors of nesting activity, including vegetative cover, aspect, and distance from water. Our results provide critical information for the management of native and invasive turtles in the Pacific Northwest. |
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4. 08:45 Using Expert Elicitation to Model Wood Turtle Demography. Hardin Waddle*, US Geological Survey; Jennifer Moore, University of Florida; Julien Martin, US Geological Survey; Evan Grant, US Geological Survey; Jillian Fleming, US Geological Survey hwaddle@gmail.com
The Wood Turtle (Glyptemys insculpta), like numerous other turtle species, is facing threats to species survival. Although much is known about the life history of the species, there are few examples of populations with comprehensive data on all population vital rates. We compiled estimates of survival and reproduction parameters from the published literature to construct a stage-based matrix population model. However, as these inputs are from disparate studies, sometimes from decades ago, it is likely that this model reflects past conditions more than current. To supplement this information and to provide a more realistic estimate of population growth rate, we conducted an expert elicitation and used aggregation methods that account for the full uncertainty around vital rate estimates. The model based on the knowledge of the expert group has more uncertainty and predicts a lower population growth rate than the literature-based one. We also elicited threats to survival of the life history stages of wood turtle to determine the effect of various natural and human-caused events on population growth. This information can be used by managers to estimate the impact of management actions and interventions on the population growth of the species. Our methodology for accounting for uncertainty and base population model are applicable to many similar species, especially other long-lived reptile species. |
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5. 09:00 Population Demography and Viability of Wood Turtles (Glyptemys insculpta). Matthew Chatfield*, University of Maine; Gregory LeClair, University of Maine; Hunter Howell, University of Miami; Cheryl Frederick, Center for Wildlife Studies matthew.chatfield@maine.edu
The wood turtle (Glyptemys insculpta) is experiencing widespread declines throughout its range in the eastern United States and Canada. Maine is considered a stronghold for the species due to an abundance of habitat and a relatively low human population density. Furthermore, recent studies have identified Maine as a potentially important climate refuge for the species. Using data collected in a five-year capture-mark-recapture study of turtles, we estimate population size, apparent survival rates, population growth rates, and population viability. We also performed a sensitivity analysis to illustrate the impacts of slight perturbations to demographic rates. Our estimated total population size is 73 (95% CI 69–85) individuals. Annual apparent survival varied across years, ranging from 77.5–99.0%, with females having a slightly higher survival (94.8%; 95% CI 81.6–98.7%) than males (93.6%; 95% CI 81.9–97.9%). The baseline population viability analysis model predicted a lambda of 0.92 (95% CI 0.90–0.95) and a 100% probability of extinction within 150 years. Despite some broad permutations in our baseline demographic parameters, there were no scenarios included within our sensitivity analysis that increased the population’s growth rate to a positive value. These results have implications for the long-term persistence of wood turtles in Maine and throughout their range. Our study helps fill a need for current data from this area that may be used to inform both local and regional management plans such as Maine’s State Wildlife Action Plan, in which wood turtles are a Priority One Species of Greatest Conservation Need. |