Kristen K. Cecala. Examining Intraguild Interactions Among Stream Salamanders: The Threat of Predation Affects Prey Behavior and Distribution. (Paper Presentation)

Predation plays an important role in structuring community composition and relative abundances of salamanders within stream ecosystems. 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 in response to the presence of P. ruber in laboratory trials, 2) investigated actual predation on D. fuscus by examining the diet of P. ruber in the field, and 3) analyzed the effect of P. ruber presence on the abundance of larval D. fuscus in 30 streams. In the laboratory, we found that larval D. fuscus chose cover objects further from a potential predator (i.e., P. ruber) than from a conspecific (p < 0.001) and would frequently leave the water to avoid a predator, despite being in the larval form. However, in the field we found that salamanders comprised only 2.5% of the diet of P. ruber larvae. 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 the behavior of prey species. Ultimately, the threat of predation may alter prey species abundances and community composition in stream ecosystems.

Steven J. Price, Kristen K. Cecala and Michael E. Dorcas. Dynamic Landscapes And The Conservation Of Stream Salamanders. (Paper Presentation)

Land-use changes, particularly habitat alteration and destruction, threaten many amphibian populations. Because landscapes are dynamic, studies of the effects of both current and historic land use on amphibians may be necessary to effectively conserve populations. In this study, we investigated the influence of land-use changes in the North Carolina Piedmont on stream salamanders by 1) examining the relationship between historic land use and contemporary patterns of abundance and species richness, and 2) documenting salamander responses to land-use changes by monitoring populations before, during and after forest clearing and the initiation of urbanization. Using historical aerial imagery, we found the amount of agricultural land within watersheds of 20 first-order streams had decreased, on average, from 60 percent to 35 percent over the last 60 years. However, the current abundance patterns of Desmognathus fuscus, Eurycea cirrigera, and Pseudotriton ruber were best predicted by land use in 1993 and 2005, suggesting that populations may not be influenced by the amount of historically degraded land within watersheds. We found that forest clearing, ranging from 20 to 90 percent, within watersheds had an immediate and profound effect on salamander abundances, as most populations of D. fuscus and E. cirrigera declined substantially within one year of forest removal. Although our examination of historical land use suggests that stream salamander populations may be capable of rebounding from past land-use stressors, the conversion of forested land to urbanized land will likely have a more profound and lasting legacy on stream salamanders than past agricultural land use.

Michael E. Dorcas, Skip Snow, Frank Mazzotti, and Michael Cherkiss. Thermal Biology of Invasive Burmese Pythons (Python molurus bivittatus) in Everglades National Park. (Paper Presentation)

Burmese pythons (Python molurus bivittatus) appear to be well established in Everglades National Park (ENP). Efforts to develop control methods for python populations are underway and knowledge of various aspects of the natural history and ecology of pythons within the park is essential to developing such controls. Because temperature affects nearly all aspects of the biology of ectotherms, examining patterns of body temperature variation can often provide insight into their activity and behavior. To better understand the ecology of introduced Burmese pythons in ENP, we initiated a radiotelemetric study of pythons within and adjacent to the ENP and monitored their temperatures using surgically implanted micro-dataloggers. We simultaneously monitored environmental temperatures. Snake body temperatures ranged 12C to 36C. During the winter and early spring, python’s were able to maintain body temperatures between 20-33C most of the time and body temperatures rarely dropped below 15C. Minimal body temperatures were experienced in late morning but quickly increased as pythons apparently emerged from retreats. During late spring and summer, variation in python temperatures decreased and maximal body temperatures increased, but pythons rarely exceeded 35C. Using these data, we hope to provide information on python thermal biology, behavior, and activity that will assist in a better understanding of their overall ecology and in development effective population controls.

Leigh Anne Harden. Terrestrial activity and habitat selection of eastern mud turtles (Kinosternon subrubrum) inhabiting gold course ponds. (Paper Presentation)

In urbanized landscapes, golf course ponds may provide the only remaining available 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. We found that mud turtle temperatures were closely correlated with environmental temperatures of the habitat they used (e.g., pond and soil). Pond emergence dates varied substantially from 15 July to 24 November 2006, with the majority of mud turtles emerging in August. Turtles moved a mean total distance from the pond of 187.2 m ranging from 44.7 to 787.9 m and moved a mean straight line distance of 119.3 m ranging from 36.3 to 581.3 m. On average, mud turtles moved 5 times before selecting an overwintering location, which was defined as (the single terrestrial location where turtles spent the most time). We determined habitat selection using logistic regression by comparing turtle locations with random locations and found that mud turtles selected forested habitats with moderate canopy cover, and little to no grass. Using a one-tailed Wilcoxon signed ranks test, we found that when selecting overwintering locations, mud turtles prefer specific habitat variables different from random locations (e.g., more herbaceous vegetation and woody debris). Overall, golf course ponds appear to provide suitable habitat for mud turtles given that there are surrounding forested habitats to provide connectivity and overwintering refugia.

Kristen K. Cecala, Steven J. Price and Michael E. Dorcas. The Spatial Ecology and Activity of Red Salamanders (Pseudotriton ruber). (Poster Presentation)

Learning more about how and why animals move is important to developing a better understanding of their ecology. Typically, stream salamanders have been described as moving primarily upstream for either avoidance of predators in higher order streams or for dispersal. However, some studies have documented downstream drift by larvae and relate those movements to base flow rates within streams. In this study, we investigated seasonal activity and movement patterns of larval red salamanders (Pseudotriton ruber) within a stream ecosystem. For one year, we systematically sampled the entire length of a 150 m first-order stream, individually marking each captured salamander. We found that larvae will frequently move large distances upstream and downstream, but second year larvae were the only age cohort to exhibit directional movement downstream (p < 0.001). Seasonal differences in movement also existed; larvae moved primarily downstream from May – October and upstream from November – February. Using number of daily captures as a measure of activity, we found that activity appeared to vary with stream water temperature (p = 0.028). These results show that larval red salamanders move frequently, yet exhibit no overall directional bias. Therefore, our study does not support either documented descriptions of stream salamander movements but demonstrates that movement may be widespread within larval stream salamander populations.

Leigh Anne Harden, Nick Diluzio, J. Whitfield Gibbons, Michael E. Dorcas. The Thermal And Spatial Ecology Of Diamondback Terrapins (Malaclemys Terrapin) In A South Carolina Salt Marsh. (Poster Presentation)

Since the 1980’s, east coast barrier islands such as Kiawah Island, South Carolina, have experienced rapid urbanization resulting in alteration of their salt marsh ecosystems. These estuarine ecosystems serve as critical habitat for numerous endemic wildlife such as Diamondback Terrapins (Malaclemys terrapin) which are particularly vulnerable to anthropogenic disturbances. To better understand the interactions between terrapins and their environment, we initiated an intensive six-day radiotelemetric study to investigate the daily movements and habitat use of five terrapins within a tidal creek. In conjunction with radiotelemetry, we used micro-dataloggers 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 (Spartina sp., mud, and occasional shallow water) than in open water of the creek channel. Terrapins remained within the same tidal creek system and moved a mean total distance of 750 m with individual total distances moved ranging from 440 to 1159 m. From 13 May until 1 June 2006, carapace temperatures of two male 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 radiotelemetry study provides new insight to understanding Diamondback Terrapin habitat use and site fidelity, which will assist in making management decisions and in developing predictive models to estimate population sizes.

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Shannon Pittman. Ecological Characteristics of a Cope’s Gray Treefrog (Hyla chrysoscelis) Population Determined Using PVC Pipe Refugia. (Poster Presentation)

Ephemeral wetlands are known to be breeding sites for many amphibian species, including Cope’s gray treefrog (Hyla chrysoscelis). The importance of terrestrial habitat surrounding wetlands to amphibian life history is known, though generally understudied. This study examined the recapture rates, habitat use, site fidelity, and growth rates of individual treefrogs within a wetland and its surrounding terrestrial habitat over a 15-month study period. Using visual implant elastomer and visual implant alpha tags, we were able to track individuals as they used a grid of 110 PVC pipes as refugia. PVC pipes allow treefrogs to be sampled when not actively calling or breeding. All captured individuals were aged, sexed, measured, and weighed. We captured a total of 82 individuals (141 captures total) with 59 recaptures, and the majority of captured frogs were male. We captured the most frogs in October of 2005 and May, June and July of 2006. Frogs occupied pipes from March through November; no frogs were found in pipes during winter months (December, January, and February). Recapture rates varied widely per month, with a decrease in the relative number of recaptures during the breeding season (May, June, and July). Frogs preferred pipes in terrestrial habitat (p < 0.05), and frogs also preferred pipes that were closer to trees (p<0.005). Frogs displayed high site fidelity, as only two frogs were recaptured in pipes different from those in which they were originally captured. Young frogs underwent rapid growth throughout the late summer and fall (0.086 mm/day), whereas adult frogs displayed minimal growth. Our results suggest that H. chrysoscelis prefer terrestrial habitat and have high site fidelity, which could have important implications for monitoring and conservation of treefrogs and other amphibians that use terrestrial habitat.