Aspects of the natural history of rat snakes (Elaphe alleghaniensis) in the western Piedmont of North Carolina. Poster Presentation.
Wes Anderson, Steven J. Price and Michael E. Dorcas.
Abstract: One-hundred eighty rat snakes were collected between 1999 and 2006. Morphological and locality data were recorded, and individuals were marked when possible. Adult males tended to be longer and heavier than females. Activity and body condition did not vary between sexes. Both sexes were captured most frequently in forest habitats. Our results show no apparent differences between males and females in seasonal activity and habitat use.
Seasonal activity and movement of larval Red Salamanders (Pseudotriton ruber). Poster Presentation.
Kristen K. Cecala, Steven J. Price, and Michael E. Dorcas.
Abstract: Movement is an important aspect of most animals’ ecology, yet few studies have examined movements within linear systems, such as streams. We sought to compare seasonal activity and movement patterns of larval red salamander (Pseudotriton ruber) age cohorts within a stream ecosystem. We found widespread movement within the stream by all age cohorts, but little directional movement. These results suggest that within some streams neither upstream bias nor downstream drift may influence larval movement.
Interspecific interactions among stream salamanders: Integrating laboratory and field studies. Paper Presentation.
Kristen K. Cecala, Steven J. Price, and Michael E. Dorcas
Abstract: Predation plays an important role in structuring community composition and relative abundance of salamanders within stream systems. In diverse salamander guilds, predation among species may occur when size differences exist that can affect prey selection, consumption rates, and microhabitat use. In this study, we examined the interactions between larval red salamanders (Pseudotriton ruber), and larval northern dusky salamanders (Desmognathus fuscus) in both laboratory and field settings. Specifically, we 1) examined the behavior and microhabitat use of larval D. fuscus to response to the presence of P. ruber in the laboratory 2) investigated actual predation on D. fuscus by examining the diet of P. ruber in the field and 3) analyzed abundance of larval D. fuscus in streams with and without P. ruber. In the laboratory, we found that larval D. fuscus chose cover objects further from a potential predator (i.e., P. ruber) than a conspecific (p= <0.001) and would frequently leave the water in their larval state to avoid a predator. However, in the field we found the salamanders composed only 2.5% of the diet of P. ruber. Yet, we captured significantly fewer D. fuscus in streams where P. ruber were present (p = 0.048). Our data suggest that the threat of predation, even if actual predation rates are low, can lead to changes in behavior of prey species. Ultimately, the threat of predation may alter prey species abundance and community composition in stream systems.
Crab Trapping Causes Population Decline and Demographic Changes in Diamondback Terrapins over Two Decades. Paper Presentation.
Michael E. Dorcas, John D. Willson, and J. Whitfield Gibbons
Award Winner: Senior Research Award.
Diamondback terrapins (Malaclemys terrapin) are thought to be declining throughout their range. Many factors have been proposed as contributing to terrapin declines, including human-subsidized predation of nests and adults, habitat loss and degradation, road mortality, commercial harvest and mortality as bycatch in crab traps, yet few studies have provided evidence directly linking these agents to population declines. Because male and small female terrapins are most susceptible to mortality in crab traps, population declines due to crab trap mortality should coincide with shifts in the age and size distributions of the population and a shift to a more female-biased sex ratio. We used 21 years of mark-recapture data (>2800 captures; 1399 individuals) from a declining terrapin population in South Carolina to test the prediction that the decline is the results of mortality in crab traps. Since the 1980's, the modal size of both male and female terrapins has increased substantially and the proportion that are females is higher. Additionally, the population demography and sex ratio suggest that this population has declined as a result of selective mortality of smaller individuals in crab traps. The use of bycatch-reduction devices on crab traps may help prevent terrapins from entering the traps, but current models are too large to prevent mortality of males and many females in this population. Future research should focus on design and testing of effective bycatch-reduction devices and other methods to reduce terrapin mortality in crab traps.
Terrestrial activity of eastern mud turtles (Kinosternon subrubrum) on golf courses: an investigation of habitat selection. Paper Presentation.
Leigh Anne Harden, Steven J. Price and Michael E. Dorcas
Abstract: In urbanized landscapes, golf course ponds may provide the only remaining suitable habitat for semi-aquatic turtles. Eastern mud turtles (Kinosternon subrubrum), which rely heavily on not only aquatic, but terrestrial habitats, may face unique challenges on golf courses with heavily modified terrestrial habitat. We conducted a radiotelemetric study of 11 mud turtles inhabiting a local golf course pond in the western Piedmont of North Carolina to investigate their terrestrial activity and habitat selection in a fragmented landscape. In conjunction with radiotelemetry, we used micro-dataloggers to continuously monitor both turtle and environmental temperatures. All but one mud turtle emerged from the pond during the summer or fall (emergence dates ranged from 15 July to 13 October 2006). Turtles moved a mean total distance of 182.2 m ranging from 0 to 787.9 m. On average, mud turtles moved 5 times before selecting an overwintering site. Most turtles selected upland forested habitat for overwintering with overwintering sites primarily consisting of moderate canopy cover (p<0.001), deep leaf litter (p=0.06), and herbaceous vegetation (p=0.06). Mud turtle temperatures were closely correlated with environmental temperatures of the habitat they used (e.g. pond and soil). Data resulting from our studies will assist in developing effective habitat management plans for wildlife on golf courses and other urbanized areas.
Spatial and thermal ecology of diamondback terrapins (Malaclemys terrapin) in a South Carolina salt marsh. Poster Presentation.
Leigh Anne Harden, Nick A. DiLuzio, J. Whitfield Gibbons and Michael E. Dorcas.
Abstract: Since the 1980’s, the rapid urbanization of Kiawah Island, SC has altered the salt marsh ecosystems that serve as critical habitat for diamondback terrapins (Malaclemys terrapin). Because of their high site fidelity, diamondback terrapins are particularly vulnerable to anthropogenic disturbances. To better understand the interactions between terrapins and their environment, we initiated an intensive 6-day radiotelemetric study to investigate the daily movements and habitat use of five terrapins within a tidal creek. Micro-dataloggers were also used to continuously monitor both terrapin and environmental temperatures. We found that during high tides, low tides, and ebbing tides, terrapins spent more time in the marsh than in open water of the creek channel. Terrapins moved a mean total distance of 750 m and a mean straight-line distance of 642 m. From 13 May until 1 June 2006 carapace temperatures of two terrapins varied from 16.0 to 41.0 C. Comparing these temperatures to environmental temperatures allowed us to make detailed inferences about basking behavior. Our short radiotelemetric study provides new insight to understanding diamondback terrapin habitat use, which will assist in developing predictive models to estimate population sizes.
The Davidson College Herpetology Laboratory's outreach program: using amphibians and reptiles as model species for environmental education. Poster Presentation.
Michelle Kirlin, M. Caitlin Westfall, Leigh Anne Harden, Kristen K. Cecala, Steven J. Price, and Michael E. Dorcas.
Abstract: Reptiles and amphibians (herpetofauna) are excellent species for use in outreach activities and environmental education programs. Herpetofauna serve important and diverse roles in ecosystems and thus learning about them increases environmental awareness. Additionally, because many can be easily kept in captivity and handled, herpetofauna offer “up-close” interactive opportunities for the public. The Davidson College Herpetology Laboratory uses herpetofauna as the focus of our outreach programs to raise awareness about the importance of herpetofauna and engage the community in projects focusing on their conservation. During the spring of 2006, the Herp Lab conducted an after-school “Science Club” at the Ada Jenkins Center focusing on herpetofauna and their importance in their environment. This project used surveys to test children’s attitudes, knowledge, and stereotypes about herpetofauna before and after the program. Herp Lab members have also designed curricula for teaching about herpetofauna and their conservation, suitable for grades K-12.
Spatial and temporal distribution of Cope's Grey Treefrogs (Hyla chrysoscelis) within a wetland. Paper Presentation.
Shannon Pittman, Amy Jendrek, Steven J. Price and Michael E. Dorcas
Abstract: Ephemeral wetlands are known breeding sites for many amphibian species, although recent studies have suggested that terrestrial habitat surrounding wetlands is also critical to many amphibian populations. Cope’s gray treefrogs (Hyla chrysoscelis) use both wetlands and terrestrial habitat, but it is difficult to study treefrogs in these habitats due to their cryptic nature and arboreal habitat use. In this study, we used PVC pipe refugia to examine habitat use, movement, and seasonal phenology of H. chrysoscelis. We placed a grid of 100 pipes throughout a wetland and surrounding upland habitat. We checked pipes biweekly for 18 months and uniquely marked or identified all individuals captured. We captured 76 individual H. chrysoscelis a total of 177 times. Nineteen spring peepers (Pseudacris crucifer) were also captured. Hyla chrysoscelis were present in pipes from late March until mid-November, but were not found during winter months. Treefrogs preferred refugia near terrestrial microhabitats with some canopy cover throughout all seasons (64 captures in 26 pipes) compared to the open wetland (1 capture within 20 pipes). Individuals exhibited high site fidelity; of 50 individually-marked frogs, only three moved to different pipes. Understanding the distribution and movement of H. chrysoscelis is important to understanding amphibian life cycles and emphasizes the importance of protecting upland habitat surrounding wetlands.
Do land-use legacies affect contempory abundance patterns of semi-aquatic reptiles and amphibians? Paper Presentation.
Steven J. Price and Michael E. Dorcas
Abstract: Studies in conservation biology and wildlife management often correlate the abundance or presence of organisms to current land cover. From these studies, inferences are often made regarding species-habitat relationships, population ecology, and, ultimately, conservation and management. However, past land use and/or cover may be an equally or more important determinant of a species contemporary distribution across a landscape. Many reptile and amphibian species exhibit low vagility and high susceptibility to habitat distrubance, suggesting that current patterns of abundance and distribution may be a reflection of land-use legacies. In this presentation, we investigate the influence of land-use legacies on current abundance patterns of semi-aquatic reptile and amphibian species in the Charlotte Metropolitan area in North Carolina. Specifically, we use aerial imagery from the 1930s through the 2005 to quantify land use surrounding farm ponds and first-order streams and relate current herpetofaunal abundance patterns in these habitats to their various land-use histories. Results provide valuable insights into reptile and amphibian population persistence and recovery, dispersal capabilities, and habitat restoration efforts. We also discuss the potential effects of current land-use attributes on future reptile and amphibian distributional and abundance patterns.
The effects of environmental variation and anthropogenic noise on calling activity of anurans. Poster Presentation.
Charlotte Steelman and Michael E. Dorcas
Abstract: To understand how environmental and anthropogenic variants affect anuran calling activity, we measured anuran calling activity at two ephemeral wetlands using automated recording systems. We describe the effects of environmental variation and airplane noise on the calling activity of winter-breeding anurans. Based on the results of this study, we provide information useful for developing effective programs based on manual calling surveys. Furthermore, we increase our understanding of the negative effects of anthropogenic noise on anuran calling.
Patterns of Trombiculid mite (Hannemania sp.) parasitism among Plethodontid salamanders in the western Piedmont of North Carolia. Poster Presentation.
M. Caitlin Westfall, Kristen K. Cecala, Steven J. Price and Michael E. Dorcas
Award Winner: Best Student Poster Award runner-up.
Abstract: Trombiculid mites (Hannemania sp.) are known to parasitize a wide variety of amphibians. We investigated patterns of parasitism among plethodontid salamanders in the western Piedmont of North Carolina. We found that three salamander species (Desmognathus fuscus, Eurycea cirrigera, and Plethodon cylindraceus) were differentially parasitized by Trombiculid mites. Our study provides a greater understanding of the patterns of ectoparasitism among salamander species, and adds information to the natural history of both Trombiculid mites and salamanders in the western Piedmont of North Carolina.
Physiological and behavioral control of heating and cooling rates in rubber boas, Charina bottae. Poster Presentation.
Ying Zhang, M. Caitlin Westfall, Kathleen C. Hermes, and Michael E. Dorcas.
Abstract: Body temperature directly impacts the ecology, behavior, and physiology of many reptiles. Consequently, many reptiles thermoregulate to optimize physiological functions. In this study, we examined the ability of rubber boas (Charina bottae) to physiologically and behaviorally control their heating and cooling rates. We measured the heating and cooling rates of rubber boas between 5° and 35° C with constrained and unconstrained postural treatments. In both the unconstrained and constrained treatments, heating rates were significantly faster than cooling rates. We conclude that rubber boas can physiologically control their heating and cooling rates. However, the ability of rubber boas to alter their heating and cooling rates via postural adjustment remains equivocal. Overall, our results provide a greater understanding of physiological thermoregulation in rubber boas and further insight into mechanisms of reptilian thermoregulation.
