Hester, Joy M., Steven J. Price, and Michael E. Dorcas. Effects of relocation on movements and home ranges of eastern box turtles (Terrapene carolina). (Poster Presentation)

Winner of the Elsie Quarterman-Catherine Keever Award presented by the Southeastern Chapter of the Ecological Society of America for the best ecological poster presented by a student.

Eastern box turtle (Terrapene carolina) populations are threatened by expanding urbanization, the resulting loss of habitat, and the introduction of threats such as roads, railroads, and pets. Individual box turtles are often captured and relocated substantial distances from their capture location by scientists, wildlife rehabilitators, and well-meaning community members. Previous studies examining the effects of relocation on box turtles are limited. Thus, we compared the home ranges, movement patterns, and mortality of resident and relocated box turtles. We radio tracked ten relocated and ten resident female box turtles on the Davidson College Ecological Preserve, in Davidson, NC, twice weekly during the active season beginning in May 2004. Geographic coordinates were recorded during each tracking session. Results suggest that relocated box turtles have larger home ranges and move longer distances per day than resident box turtles. Additionally, relocated turtles had higher mortality and disappearance rates than resident turtles. Our preliminary results indicate that relocated box turtles do not quickly reestablish home ranges in a new habitat, and may attempt to leave their relocation site, thus, raising questions about the success of relocation as a conservation strategy for eastern box turtles.

Hill, E. Pierson, William J. Johnson, and Michael E. Dorcas. Habitat selection in black ratsnakes (Elaphe alleghaniensis) in the western Piedmont of North Carolina. (Poster Presentation)

Habitat fragmentation is a well-documented cause for species decline and extinction, especially in reptiles. However, some species may benefit from moderate anthropogenic disturbances to habitats that create high edge to interior ratios. The Eastern Ratsnake (Elaphe alleghaniensis) can be found throughout areas of human development as well as undisturbed forest habitats in the Piedmont of North Carolina. To examine how ratsnakes use macrohabitats in a fragmented landscape, we radiotracked 14 snakes over a three-year period on the Davidson College Ecological Preserve in Mecklenburg and Iredell Counties, NC. Snakes were found to use kudzu patches more than expected by their availability and avoided planted pine forests (p<0.001). We found considerable inter-individual differences among snakes in their preferred habitats with some individuals selecting habitat types others avoided. All snakes had a strong preference for edge habitats, defined either at 10-m and 20-m distance intervals (p<0.001). Overall, moderate fragmentation due to anthropogenic modification of the landscape appears to result in habitats favored by Eastern Ratsnakes.

Johnson, William J., E. Pierson Hill, and Michael E. Dorcas. Home-range size and site fidelity of Eastern Rat Snakes (Elaphe alleghaniensis) in the western Piedmont of North Carolina. (Poster Presentation)

Understanding an animal’s spatial ecology is a necessary component of conservation, particularly where urban development alters habitat. Many species show repeated use of specific locales within their environment and could be imperiled if those frequented areas are disturbed or eliminated, forcing the animal to move elsewhere. We examined the spatial ecology of the eastern rat snake (Elaphe alleghaniensis) by radiotracking 13 snakes over a three-year period on the Davidson College Ecological Preserve in Mecklenburg County, NC. Snakes had an average active-season home-range size of 8.7 ha (measured as 95 % kernel). Many of our snakes showed repeated use of particular areas within their home ranges over the duration of the study; with 17% of core areas and 35 % of successive years’ home ranges common to both years, with no difference between sexes. Conservation lessons learned from common species such as the rat snake can be applied to more imperiled species.

Kornilev, Yurii V., Steven J. Price, and Michael E. Dorcas. Responses of eastern box turtles (Terrapene carolina) when trapped between railroad tracks. (Poster Presentation)

Anecdotal accounts of eastern box turtles (Terrapene carolina) found dead between railroad tracks suggest that their populations might be negatively impacted by such structures. To investigate the potential impacts of railroads on box turtles, we recorded the number of climbing attempts, the distance moved, the overall speed of travel, and the exit behavior of 12 adult animals experimentally trapped for 1 hr between railroad tracks. Additionally, we examined the temperatures box turtles experience between rails. Only one individual escaped by climbing over a rail. The total distance moved by the majority of tested turtles was less than 100 m during the observation period. When presented with the option to leave at a railroad crossing, 3 turtles stayed between the tracks, 4 exited and headed towards an adjacent parallel road with moderate traffic, and 5 headed in the opposite direction towards a vegetated field. The mean distance between railroad crossings in our study area is 379 m; more than 50% of the crossings are separated by more than 200 m. Thus, at least two hours would be necessary for a box turtle consistently moving in its original direction to get from one railroad crossing to another. However, on a mild day (air temperature = 24 C) the core body temperatures of turtles trapped on railroads may reach lethal temperatures within this time. Railroads, like other human transportation infrastructures, likely serve not only as sources of direct mortality, but as barriers to turtle dispersal, leading to population declines and fragmentation.

Gooch, Michelle M., Aubrey M. Heupel, Steven J. Price, and Michael E. Dorcas. The effects of survey protocol on detection probabilities and site occupancy estimates of summer-breeding anurans. (Poster Presentation)

Recent declines in amphibian populations have created an urgent need for monitoring efforts and many anuran monitoring programs have been established that utilize calling surveys. Calling surveys can be effective monitoring tools; however, differences among survey protocols often bias survey results. Failure to take into account detection probabilities when monitoring anurans can lead to inaccurate inferences about site occupancy, since non-detections in survey data do not necessarily mean that a species is absent unless the probability of detection is 1. We used the likelihood-based computer program PRESENCE to estimate detection probabilities and site occupancy rates for summer-breeding anurans. Using detection data from calling-surveys, we evaluated how detectability and site occupancy for 5 anuran species were influenced by 1) time spent listening at each site, 2) number of surveys per site, and 3) sample- and site-specific covariates. We found that detectability varied more with sampling occasion than with survey duration for each species; longer surveys did not significantly increase detectability for any species. Covariates had differing effects on occupancy and detectability among individual species. Multiple surveys per site within a season are necessary to eliminate biased detection probabilities, but we found that 3- or 5-minute surveys are adequate for detecting all species.

Sarah A. Budischak, Joy M. Hester, Michael E. Dorcas, and Steven J. Price. The natural history of box turtles (Terrapene carolina) in an urbanized landscape. (Poster Presentation)

Globally, many turtle species are experiencing population declines due to anthropogenic causes. Eastern box turtles (Terrapene carolina) are important components of the biota of eastern forests and in developing areas. Therefore studies are needed to estimate the effects of urbanization and to develop proper conservation strategies for these animals. In 1999 we initiated a long-term mark-recapture study of eastern box turtles in the vicinity of Davidson College, Davidson, NC. We used data from this study to describe the natural history characteristics of this box turtle population and to examine potential effects of urbanization. Specifically, we examined meristic characteristics, turtle condition, activity patterns, population structure, and growth rates in conjunction with the amount of anthropogenically modified habitat within 100 m of each turtle’s collection location. Males and females exhibited different, seasonal patterns of activity, measured by collection dates, and body condition, measured using the residual of a mass/carapace length ratio. Growth rates decreased with turtle age and varied between developed and forested habitats. Growth ceased at approximately 15 yrs. Proportionally, the oldest turtles were found in areas with extensive forest cover, as opposed to highly developed areas. Condition did not vary by amount of forest cover for males or females. Studies such as this one, which describe basic natural history characteristics and how those characteristics are affected by urbanization, form the first critical step in developing sound conservation strategies for box turtles in the eastern United States.

Cobain, Erin F., William C. Haas, and Michael E. Dorcas. An Investigation of Physiological and Behavioral Thermoregulation during Heating and Cooling in Charina bottae. (Poster Presentation)

Temperature variation has important functional consequences for snakes. Thus, thermoregulation is central to survival. Large reptiles are capable of increasing heating rates and reducing cooling rates using both physiological mechanisms (i.e. controlling blood flow) and behavioral mechanisms (i.e. altering their surface area to volume ratio). The ability to alter heating and cooling rates has rarely been examined in small reptiles. We investigated the ability of rubber boas (Charina bottae), a relatively small snake, to physiologically and behaviorally adjust rates of heating and cooling. In this investigation, temperature sensitive PIT tags were implanted into the bodies of ten captive rubber boas. The snakes were then subjected randomly to four heating and cooling treatments over a 5-33°C temperature range: 1) heating in a constrained position (i.e. held straight), 2) cooling in a constrained position, 3) heating in an unconstrained position and 4) cooling in an unconstrained position. The thermal time constant, the time required to reach 63% of its final temperature, was calculated for each snake in all treatments. Preliminary results have yielded three general conclusions: 1) larger snakes had greater thermal time constants than smaller snakes in all treatments, 2) rubber boas generally heated faster than they cooled and 3) rubber boas that were constrained had a faster rate of temperature change for both heating and cooling treatments than unconstrained rubber boas. Our results suggest that some small reptiles may possess both physiological and behavioral mechanisms by which they can alter rates of heating and cooling.

Price, Steven J.1, Michael E. Dorcas1, Alisa L. Gallant2, Robert W. Klaver2, and John D. Willson3. 1Davidson College, Davidson, NC 28035-7118, 2USGS/EROS Data Center, Sioux Falls, SD 57198, 3Savannah River Ecology Laboratory, Aiken, SC 29802

Impact of land cover change on stream salamander populations in the Piedmont of the eastern United States. (Oral Presentation)

Most scientists consider habitat loss and degradation to be the major threat to amphibian populations. Studies of land cover changes from 1972 to 2000 in the Piedmont of the eastern United States show a significant increase in the amount of urban land cover and a corresponding reduction in the amount of forested habitat. Small streams in the Piedmont support high densities of salamanders and are often the first aquatic habitats to be affected by landscape-altering factors such as urbanization and pollution. Landscape changes in the Piedmont have likely resulted in a significant decrease in stream salamander abundance, but the magnitude of this change is unknown. The objective of this study was to estimate the change in abundance of stream salamanders in small watersheds in the Piedmont region of the eastern United States over the last 3 decades. We used US Geological Survey (USGS) Land Use/Land Cover trend data to quantify land cover changes within small headwater stream watersheds in the Piedmont. Changes in salamander abundance were estimated using models which allow predictions of the relative abundances of salamanders based on land cover within each watershed. Results of this study will help scientists and policy makers understand the significance of habitat alteration on amphibian populations. This project was supported by Duke Energy, the National Science Foundation, and the USGS Amphibian Research and Monitoring Initiative.