In the Shadows of a Brownfield: Nest Site Selection by Marbled Salamanders (Ambystoma opacum) in an Isolated Wetland in Southeastern Tennessee
Amphibians have complex life cycles and most require unrestricted access to both upland and wetland habitats. A critical component of amphibian life history is nest site selection, and this can be fairly dynamic at a variety of spatial and temporal scales. We examined biophysical aspects of nest site selection of Marbled Salamanders (Ambystoma opacum) at a wetland adjacent to an industrial development in southeastern Tennessee. We conducted nest site surveys daily from 10/15/13 to 10/31/13. We targeted all representative habitats in the wetland, yet most nests were detected in the wetland-upland interface. We generated random points based on each nest as a means to compare the biophysical conditions in areas where nests were present versus undetected. We recorded data for 40 nests over a suite of biophysical variables that included, water depth, distance from nearest water, distance from hydrologic boundary, percent cover, soil type, elevation, and aspect. After we described the physical nest site and surrounding landscape, we constructed a predictive model using regression and Akaike Information Criterion to rank and evaluate the associations between nest sites and biophysical features. Marbled Salamanders selected nest sites that had hydric soils with abundant cover but not ranging too far from standing water. Our data suggest that Marbled Salamanders select sites in a non-random fashion, and did not nest in all available microhabitats. Stakeholders can use this information that incorporates hydrology and vegetation structure to make informed decisions that benefit this species.
1 Dept of Biological and Environmental Sciences, University of Tennessee at Chattanooga, Chattanooga, TN; 2Battle Academy, Chattanooga, TN
198 • Adrian K. O. Hayes, Elliott P. Gibbs, Melissa A. Pilgrim
Interspecific Variation in Nocturnal Calling Activity of Anurans Influenced Call Survey Estimates of Species Occurrence in the Piedmont Region of South Carolina
The North American Amphibian Monitoring Program (NAAMP) uses a standardized call survey protocol to evaluate presence and persistence of anurans in a region. One aspect of NAAMP protocol is that stops along a call survey route must be conducted in sequential order between thirty minutes after sunset and one in the morning. Such a sampling regime introduces potential temporal bias to call survey data if anuran calling activity changes through the night. Our study objectives were to evaluate (1) whether anurans in our region showed temporal variation in calling activity through the night and (2) if patterns in calling activity through the night impacted sampling effort necessary to detect anuran species. To address our objectives, we used Automated Recording System (ARS) sound files recorded at four wetlands in the Piedmont region of South Carolina from May 13th - June 17th, 2012 (dates overlapped NAAMP Sampling Window 3). Using NAAMP protocol, we completed 560 call surveys at four five-minute recording periods (i.e., 21:30, 22:30, 23:30, and 00:30). Logistic regression analyses revealed that calling activity of Acris crepitans, Lithobates catesbeianus, and L. clamitans significantly increased further from sunset, while calling activity of Anaxyrus fowleri, Hyla chrysoscelis, and H. cinerea significantly decreased further from sunset. The influence of time on anuran detection was most pronounced for A. fowleri and H. cinerea, where reversing the sequence of call survey completion at least doubled the sampling effort necessary to detect each species. Our research indicated that NAAMP protocol may underestimate anuran occurrence in our region.
Biology, University of South Carolina Upstate, Spartanburg, SC
199 • Alyssa A. Hoekstra, Vincent A. Cobb
Thermal Ecology of the Timber Rattlesnake (Crotalus horridus) in Middle Tennessee
Timber Rattlesnakes commonly make lengthy movements to and from foraging areas during their active season, exposing them to a variety of habitat. In the Eastern U.S., fragmented habitats have become common and are generally considered a negative environmental feature in snake ecology studies. Because of the importance of body temperature selection in snakes, we hypothesized that these fragmented habitats might limit movement patterns due to differences in the availability of appropriate temperatures. Using radio-telemetry and temperature loggers we recorded body temperatures of free-ranging timber rattlesnakes during their active season. We also used operative snake models to monitor the thermal characteristics of four different habitat types that are frequently used by this snake population. We found that body temperatures of snakes were within or below the range of available environmental temperatures depending on the type of habitat. Open canopied habitats offered a wide range of temperatures with higher extremes than forested habitats but were only used by snakes if they chose patches of dense vegetation within. Additionally, snakes commonly used the open habitat edges. Operative models indicated that habitat edges had steep thermal gradients. This study suggests that altered and fragmented habitats with limited microhabitat diversity can provide appropriate shelter from extreme environmental conditions but may dictate snake movements potentially making them predictable targets for predators.
Dept of Biology, Middle Tennessee State University, Tennessee, TN
200 • Soraya M. Bartol1, Ian K. Bartol2, Ashley L. Lavender2
