The Bog Turtle (Glyptemys muhlenbergii) is a federally threatened species that occupies isolated pockets of open-canopy fens. This long-lived species is susceptible to habitat loss and degradation; thus, the conservation of known populations and management of their habitat is critical to the species’ survival. Long-term (multi-decadal) assessment is important for determining population trends and responses to ongoing habitat management. I assessed population demographics (abundance, survival) and spatial distribution (home range) of two Bog Turtle populations in Massachusetts that have been managed since the late 1990s by treating invasive species, thinning woody vegetation, and mitigating flooding. The results of this study were compared to two previous studies conducted in 1994–1997 and 2005–2009 to evaluate the response to habitat management. Estimates of adult population abundance increased from the first study period (Site 1 X̅= 37.3 ± 10.4, Site 2 X̅= 36.2 ± 3.2) to the last study period (Site 1 X̅= 65.1 ± 17.9, Site 2 X̅= 42.5 ± 10.9) across both sites. Estimates of annual survival across all study periods remained above 90% at Site 1 and were 100% for two years at Site 2. I constructed 95% minimum convex polygon (MCP) and 95% kernel density estimation (KDE) home ranges for 71 turtles. At Site 1 there was no significant influence of the study period on home range estimates. The increase in abundance estimates, high survival, and stable home range sizes at Site 1 suggest that ongoing management has maintained quality habitat. At Site 2, the average home range size decreased by approximately half after the first study period in response to flooding but increased in the current study. Fluctuations in population abundance, and home range size at Site 2 throughout the study period reflect the cycles of habitat degradation and habitat management. My results indicate that habitat management efforts implemented since the late 1990s have provided quality habitat for the two Bog Turtle populations in Massachusetts while also mitigating long-term negative impacts on the populations. This further supports the need for long-term analysis of Bog Turtle populations, especially at sites where active habitat management is occurring.

Bog turtles (Glyptemys muhlenbergii) are a small freshwater turtle ranging east of the Appalachian Mountains from New York to Georgia, in small, patchily distributed (<10ha) groundwater fed wetlands. Despite their name, these wetlands are more appropriately identified as seep meadows or fens owing to their reliance on groundwater, with bogs being typified by precipitation as the major hydrologic input. Groundwater inputs are not only important in taxonomically classifying wetland type, but also contribute in important ways to bog turtle natural history. Bog turtles ectothermically regulate body temperature by utilizing thermally buffered groundwater inputs during seasonal extremes. Perennially saturated wetland areas disrupt the establishment of facultative wetland vegetation or woody vegetation that may induce wetland succession, maintaining adequate bog turtle habitat. Further, groundwater input mechanistically contributes to microtopographic variation, providing viable nesting locations. Hydrologic studies pertaining to these wetland habitats has been limited in scope, and often attempts to define hydrologic regimes by use of a centrally placed monitoring well. Several studies that have comprehensively monitored these seep meadow wetlands show hydrologic regime variability at intrasite scales. In this thesis, I sought to confirm the spatially variable nature of hydrologic regimes in bog turtle wetlands. Finding that hydrologic conditions were location-dependent, I then tested whether a seep to non-seep hydrologic gradient, or the defining physical components therein, explained variation in bog turtle population density across a wetland. In Chapter II, I observed wetland conditions in summer extremes to categorize wetland areas based on surface saturation into seep, always wet, and sometimes wet locations. I placed multiple water level monitoring wells within these categories at six bog turtle wetlands and used observed water level data to test for spatial hydrologic variability at within- and across-site scales, finding that hydrologic regime can vary at short distances (<10m), and that alike categorized wells differed in groundwater inputs across-sites. I then used observed water level monitoring data during the growing season to test initial observer-based classifications. These classifications were then reorganized using the amount of time water remained near the soil surface, the degree of fluctuation that water level experienced, and differences in thermal exchange with ambient air temperature and thermally buffered groundwater input. I created a method to delineate spatially variable hydrologic regimes based on groundwater discharge by using several seep-associated features. Soil water temperature, depth to resistive soil layer, and specific conductivity were tested for sampling applicability across seasonal extremes, and for co-occurrence in constrained ordination with spatially explanatory covariates. I found that spatial gradients for relative measures of each seep-associated feature were largely consistent across seasons and that all seep-associated features were more often correlated than any other spatial arrangement. Constrained ordination model results were visualized to depict the seep to non-seep hydrologic gradients found within these wetlands. These gradients were then tested against observed water level data for their predictive capability, finding mixed results across seasons and that hydrologic gradients as modeled could likely be improved with additional explanatory information. Depending on where groundwater is entering a wetland, habitat conditions might vary for bog turtles. Seep areas create perennially saturated or mucky soil conditions, with locations further from groundwater discharge experiencing total or some degree of drying out in the growing season. Bog turtle habitat associations recorded in literature suggest that bog turtles are typically found in or near these soft mud or open water areas. Constant groundwater input near these seeps also leads to rivulet formation. Cool, gently flowing water weaves between hummocks of vegetation near these locations, creating pathways for easy movement, elevated platforms for turtles to bask, and muddy substrates to which turtles can retreat to. Because of the habit conditions afforded by these seep areas, I hypothesized that turtle density might be higher with seep occurrence as influenced by the underlying wetland hydrologic gradient. In Chapter III, I tested whether bog turtle population density was a function of hydrologic features across seep to non-seep gradients, relative soil water temperatures, the depth of substrate above a consolidated soil layer, and relative soil moisture conditions. In the summer of 2022, I trapped at six bog turtle wetlands and tracked 24 bog turtles with radiotelemetry. I used a spatially explicit capture mark recapture framework to estimate density and used data developed for hydrologic datasets in Chapter II to examine density associations. Bog turtle density relationships to hydrologic covariates varied across wetlands and supports the view that bog turtles in their active season are not particularly sensitive to specific hydrologic regime conditions, but rather utilize the entirety of wetland conditions. / Master of Science / Bog turtles (Glyptemys muhlenbergii) are a small freshwater turtle ranging east of the Appalachian Mountains from New York to Georgia, in small, patchily distributed (<10ha) groundwater-fed seep meadows and fens. Groundwater inputs create these wetlands and conditions necessary for bog turtle survival. Hydrologic studies in these wetland types are limited but hint towards a reliance on groundwater input as contributing to hydrologic regimes that are locationally dependent. In this thesis, I sought to confirm the spatially variable nature of hydrologic conditions in these wetlands by focusing on ground water entry points and testing whether seeps, or associated seep characteristics, influenced bog turtle population density across a wetland. In Chapter II, I used water level monitoring wells to establish that hydrologic regimes in bog turtle wetlands are spatially variable and characterized these regimes by the resulting saturated to dry surface conditions. I then selected wetland features hypothesized to be associated with groundwater discharge locations and provided evidence that these features occur together and are seasonally constant. These features were then used to delineate hydrologic gradients and tested for whether they could predict conditions observed in water level monitoring. Hydrologic gradients drawn from seep to non-seep locations had limited ability to predict observed hydrologic regimes. Ground water seeps are considered to contain necessary habitat conditions for bog turtles as thermal and predatory refugia, a mechanistic disturbance favoring herbaceous vegetation over woody vegetation, and provide processes that establish microtopographic variation favorable to bog turtle nesting behavior. In Chapter III, I used delineated gradients from the preceding chapter to assess underlying hydrologic conditions that explain where turtles are more likely to be found within their habitat, and whether these associations were shared across bog turtle populations. Bog turtle density across wetlands differed by hydrologic-associated features, and findings suggest that site-wide variability in conditions is the more important aspect of bog turtle wetlands than a specific hydrologic regime.

Reptile populations are in decline worldwide, with turtle species showing some of the largest drops in population. The bog turtle (Glyptemys muhlenbergii) is considered one of the rarest North American turtle species, and this rarity is made more severe by anthropogenic factors. The wetland habitats that are used by bog turtles contain seepage areas and soil saturation that are characteristic of specific types of wetlands, suggesting that bog turtle rarity may in part be attributed to narrow habitat requirements. In this dissertation, I have sought to spatially and temporally characterize the hydrology and soils of wetlands that are used by bog turtles in an effort to determine how these factors are related to the species' habitat requirements, movement, and activity. In Chapter 1, I evaluated hydrology over a continuous 28-month period using shallow groundwater wells in six wetland fens known to be used by bog turtles for breeding and six apparently similar, but unused, wetlands. The saturated surface area near wells was measured and correlated with depth to the water table. Overall, water tables remained high, with mean monthly depth to the water table for all 12 wetlands remaining > -35 cm (depth below surface datum is negative). Bog turtle breeding wetlands had significantly higher mean water tables and surface saturation than wetlands where no turtles were encountered, particularly during and after the two-year drought occurring in 2007 and 2008. Findings of Chapter 1 suggest that relatively small differences in water table hydrology can affect bog turtle biology and use of wetlands. Bog turtles access soils and move through them to thermoregulate, find cover, and hibernate. Most wetlands used by bog turtles are also grazed by livestock that can modify soil strength. In Chapter 2, I identified dominant soil series and sampled surface soils from wetlands used by bog turtles and similar, but unused, wetlands. Samples were analyzed for organic carbon content and particle size distribution. Organic carbon content was greater in areas that were always wet (10%) than temporarily wet areas (5%). Somewhat higher organic carbon contents were present in wetlands that were used by bog turtles (8.8%) than wetlands where turtles were never encountered (5.7%). Soil textures were sandy loams and silt loams on all the study wetlands. Based on measurements of soil strength made with a static cone penetrometer, bog turtles selected wetland locations with low-strength soils. The mean and variability of soil strength were no different between grazed and ungrazed areas. The physical qualities of surface soils in bog turtle wetlands are dependent on consistently high water tables. In Chapter 3, I described three field studies in which I deployed temperature loggers to measure and contrast ambient air and soil temperatures to turtle carapace temperatures during activity and hibernation. I used temperature signatures to evaluate the timing and cues of spring emergence and to recognize thermoregulatory activities during periods of turtle activity. Mean daily turtle temperatures (n=16 turtles) during the coldest portion of two winters ranged between 1.3°C and 6.1°C, with one turtle experiencing 14 continuous days at temperatures between -1°C and 0°C when ambient temperatures dipped below -10°C. Water tables remained within 10 cm below the soil surface throughout the winter, preventing freezing temperatures for shallow hibernating turtles. Soil temperatures at 10 cm depth were a primary cue for spring emergence. Daily mean summer turtle temperature (n=8) was 20.8°C. My findings indicated that the presence of water near the surface and the ability for turtles to submerge themselves in mud are important for thermoregulation. In Chapter 4, I used radio telemetry to evaluate bog turtle activity (distance moved / hour), linear range, and the pathways used for dispersal. I also investigated bog turtle activity during sampling periods with either wet or dry hydrology. Mixed model analysis indicated that turtles were much less active between 18:30 and 09:30 relative to the daytime and that turtles were most active during times when hydrology was categorized as wet during 2008 when moderate to severe drought was the dominant condition. Sex was not a factor in turtle activity. Bog turtle paths during large movements (≥ 80 m) were mostly contained to areas within 80 m of USGS 7.5â quadrangle mapped streams. Turtles made large movements more frequently during dry conditions. Results suggested that drying conditions can stimulate bog turtles to either remain inactive in sparsely available saturation or to move long distances to find wetter conditions. Future conservation efforts should focus on allowing safe dispersal among habitats by reducing obstructions and risks to travel near streams. I n chapter 5, I used GIS-derived data to compare land cover, stream order, topographic wetness index inverse, presence of hydric soils, and presence of National Wetland Indicator (NWI) wetlands on bog turtle occupied wetlands (n=50) to the same variables on apparently unoccupied (n=48) wetlands or random areas (n=74) along streams. Occupied areas differed from random areas in having near zero values of the topographic wetness index inverse (indicating areas with low slopes and large upstream drainage areas that are more prevalent in wet portions of the landscape), the presence of > 50% low vegetation typical of non-forested agricultural areas, and presence of 3rd order streams. I used significant regression coefficients to create a GIS layer of high quality bog turtle habitat over the landscape, and tested this layer with bog turtle field survey data collected in 2009 independently of model building data. The resulting model has the potential to quickly rule out large portions of the landscape as potential bog turtle habitat. Finally, in Chapter 6, I provided general recommendations for managing bog turtle habitats in Southwestern Virginia. Managing bog turtle wetlands must emphasize the maintenance of high water tables, while avoiding inundation. Maintaining connectivity among wetlands used by bog turtles is an important aspect to consider when developing bog turtle conservations plans associated with development and other land use changes. Educating landowners and enforcing existing wetland laws are imperative for effective bog turtle management in Southwestern Virginia. / Ph. D.

Freshwater turtles are among the most threatened groups of taxa globally, and the bog turtle, Glyptemys muhlenbergii is among the most imperiled in North America. In Virginia, USA, bog turtles are restricted to occupying Appalachian Mountain fens. Fens are naturally small and fragmented wetlands characterized by elevated water tables and an open canopy. Although there is a strong need to document and monitor populations of bog turtles, efforts to do so are often limited by the low detection of the species. The first objective of this thesis was to assess proposed methodologies for locating populations of turtles on the landscape. My first chapter assessed a previously-developed habitat distribution model for bog turtles using an occupancy modeling approach. I conducted 216 surveys of 49 discretely predicted patches of habitat, recording conditions such as weather, size of wetland and time of year, hypothesized to affect detection during each survey. In addition, I assessed factors including stream entrenchment, grazing presence and surrounding impervious surfaces for each surveyed patch to identify data sources that could improve future models or better assess sites. I found that sites with larger total wetland area had higher detection per survey, possibly due to larger sites having higher densities of turtles (among other explanations), and that sites with higher amounts of impervious surfaces within their drainage were less likely to be occupied. In addition to the bog turtle, several plant species also occur in mountain fens. These species usually have a locally rare distribution or are disjuncts from a more northern latitude. Because of these traits, a high diversity of specialist plants may be indicative of a fen with a robust hydrology that has historically been less disturbed. Past site quality analyses have proposed using indicator diversity to assess sites, but no study has found if these species to tend to co-occur. My second chapter examines this hypothesis. I first chose a list of plant species that would most likely have habitat requirements similar to those of turtles. Then, at 12 sites, 6 with turtles and 6 without, I conducted a complete floral inventory. I first tested community-wide differences between the floral communities of these sites and found no difference, but when I narrowed my analysis to examining occurrence patterns of plant species determined a priori to be fen specialists and Glyptemys muhlenbergii, a pattern of co-occurrence was found. This lends support to the idea that indicator plants could be used as a tool to better evaluate sites that may have bog turtles. My last chapter investigated movement of bog turtles in a landscape impacted by anthropogenic development. Movement of turtles between adjacent sites is critical to maintaining genetic diversity and maintaining metapopulation integrity. Despite this importance, records of long distances movements among wetlands are scarce in the literature, likely due to the lack of long-term studies for areas with multiple adjacent sites. In Virginia, mark recapture monitoring has been done intermittently in a cluster of sites for over 32 years. To determine the prevalence of movement among sites for bog turtles, I examined the dataset for all instances of turtles found at sites different from their last capture. I calculated the straight-line distance for each recorded movement. I also examined the sex of the turtle to test whether sex influences movement the frequency and distance of movements. For a subset of movements, I calculated least-cost pathways to identify possible barriers to movement using a previously published resistance model. I found 21 instances where a turtle was caught at a different site than its last capture over 32 years of monitoring. Neither sex was more likely to move farther than the other. Although the study's observed rate of movement may appear low, it is likely an underestimate when detection and asymmetric sampling are taken into account. The least cost pathways analysis suggested that roads or driveways were likely crossed for a significant portion of movement events. Finally, to examine how movement may be affecting the current distribution of bog turtles, I described a method to test whether adjacency to known populations influences the probability of a new site being occupied by turtles. I prove the utility of the method by applying it to a map of bog turtle occurrences collected over this study and show that it can account for habitat differences and barriers to movement between sites as well. In spite of plausibility of the method, limitations in how occurrence data are currently collected prevent its immediate application. Together, this thesis will help managers not only find and assess wetlands on the landscape, it will also provide information about the network of connected patches on the landscape. Knowing where bog turtles are and what wetlands or sub-populations are potentially connected will allowed for a more directed and informed regional management strategy. / Master of Science / Freshwater turtles are facing population declines worldwide, and the bog turtle Glyptemys muhlenbergii is among the most imperiled in North America. Bog turtles occupy naturally small, specialized wetlands called Appalachian Mountain fens. The prevalence of fens on the landscape has declined over recent decades due to agricultural practices. Although there is a strong need to document and monitor bog turtle populations due to their threatened status, bog turtles are difficult to find due to their small size and ability to burrow completely into substrate. Thus, considerable effort must be expended to find populations and track their status. The first overall objective of this thesis was to assess methods for locating populations of bog turtles. My first chapter tests a habitat distribution model that uses publicly available landscape data such as topopgraphy and land cover to predict areas likely to contain turtles. To do this, I systematically surveyed 49 predicted sites multiple times each over 2 years. Simultaneously, I recorded variables such as the time of year, size of the wetland and the weather to determine whether any factor significantly explained the ability to find turtles on any given survey. In addition, I was able to record several variables relating to wetland quality and isolation that were not in the initial model. I found that larger wetlands were easier to search than smaller wetlands, possibly due to larger sites having more turtles, and that wetlands near more impermeable surfaces (such as roads and buildings) were less likely to have bog turtles. As another potential method to find bog turtles and assess sites, we tested the use of 'pristine indicator' plants as a metric for potential wetlands. Mountain fens have specific attributes, such as high groundwater influence and exposure to a large amount of sunlight. Several species, including the bog turtle, are specialized to these factors and are rarely found in the surrounding landscape. Because a distinct community exists for mountain fens in this region, sites with a higher diversity of fen specialist plants may be indicative of a higher quality site which can support more specialists, including the bog turtle. My second chapter tests this hypothesis. I first chose a list of species that would most likely have habitat requirements similar to those of bog turtles. Then, at 12 sites I documented every plant species I encountered within the wetland. I compared the plant community as a whole between bog turtle-occupied and unoccupied sites and found no significant difference between the two. When I narrowed my analysis to focus on plants I previously identified as sharing habitat requirements with the bog turtle, I found a strong pattern of their co-occurrence with bog turtles. This lends support to the idea that these 'pristine indicator' plants could be used as a tool to better evaluate sites that may have bog turtles. My last chapter investigates movement of bog turtles in a landscape impacted by human development. Movement of turtles between adjacent wetlands is critical to maintaining long term regional viability of the species, as it lets turtles colonize new sites and exchange genes. Despite the importance of these movements, records of turtles moving long distances between two wetlands is scarce in the literature, likely due to the lack of long-term studies for areas with multiple adjacent wetlands. One method of recording movements is by marking turtles with a unique ID and recording where it was encountered as wetlands are surveyed on the landscape. In Virginia, this procedure has been conducted at multiple sites over 32 years. To understand the prevalence of movement between sites for this species, I examined this dataset and examined all instances of a turtle being found at a site different from its last capture. I recorded the straight-line distance moved for each recorded movement as well as the sex of the turtle, to test if either sex was more or less likely to undertake these movements. Then, for a subset of movements, I calculated least-cost pathways, a metric that accounts for landscape features and plots the easiest route for turtles to move. This way, I could evaluate the prevalence of barriers to movement, such as roads or development, on the landscape. I found 21 documented movements among sites over 32 years of monitoring. Neither sex was more likely to move further than the other. Compared to studies looking at other freshwater turtles, the observed rate of movement appeared low, but this was likely an underestimate due to the difficulty of capturing specific individuals. I also found evidence of significant barriers to movement in 13 out of 17 evaluated least-costs paths, usually roads or driveways. Finally, to examine how movement affects bog turtle distribution, I describe a methodology of testing if adjacency to known populations influences the probability of a new site being occupied by turtles. I demonstrate the plausibility of the method by applying it to a map of occurrences collected over this study and show that it can account for habitat differences and barriers to movement between sites as well. However, limitations in my sampling scheme limit conclusions from my dataset. Together, these findings will help future managers find where turtles are and which sites may be connected. These results will help managers make more informed decisions for managing bog turtles at a statewide level.