Quantifying Anthropogenic Threats and Ecological Parameters of a Southern Appalachian Endemic, Weller’s Salamander

Rosemary Ronca

Appalachian State University

November 2023

The Appalachian mountains are home to a large number of endemic amphibian species, many of which have been chronically understudied. In the face of the current mass extinction event, ensuring that we have a thorough understanding of the amphibian species in this region, and their parameters for survival, will allow us to best manage and protect those species. One of the understudied amphibians in this region is the Weller’s Salamander (Plethodon welleri), which occurs in Western North Carolina, Northeastern Tennessee, and Southwestern Virginia.

Weller’s Salamander individual found in Ashe County, NC. – Rosemary Ronca

After being discovered in 1930 by the young naturalist Worth Hamilton Weller, and later described by Charles Walker, little research has been done into the ecological parameters of this species. What we do know comes primarily from James Organ, who studied the life history of this species after collecting egg masses in the late 1950s (Organ 1960), and a genomics case study that looked into the potential connectivity between populations (Forester 2017). However, there are still many questions regarding habitat parameters and community interactions.

This was the basis for my thesis research while at Appalachian State University. I wanted to help fill in the gaps in what we know about this salamander, and help identify potential predictors of both habitats where they may occur, and when they might be surface active. Based on previous literature, Weller’s Salamander populations have mainly been encountered in summer months, and are considered a high-elevation, spruce-fir specialist occurring primarily at elevations over 1,500 m, or 5,000 ft. Interestingly though, a few populations were found as low as 700 m, or 2,300 ft in the Tennessee portion of their range.

Landscape image of one of the mountains where our 2022 surveys were conducted. – Rosemary Ronca

For this study, I surveyed forested areas within the North Carolina and Tennessee portions of Weller’s Salamander’s range. I conducted visual encounter surveys lifting natural cover objects (rocks, logs, etc.) from March to November 2022 with the help of undergraduate and graduate student volunteers. We encountered individuals of 10 salamander species: Weller’s, Eastern Red-backed, Southern Ravine, Northern Gray-cheeked, White Spotted Slimy, Yonahlossee, Northern Pygmy, Blue Ridge Dusky, Blue Ridge Two-lined, and Red Salamanders.

Grant recipient Rosemary Ronca (front) and two undergraduate volunteers hiking to field plots in North Carolina. – Rosemary Ronca

While at our field sites, we also collected environmental data including air temperature, humidity, windspeed, leaf litter depth, soil moisture and pH, and canopy cover. We used Daymet’s daily surface weather data to collect precipitation data including rainfall amounts for the week prior to our survey visit and the number of days that had passed since the last rain event. We also derived site characteristics from QGIS using a 30m resolution digital elevation model, such as elevation, aspect, slope, and other indices which can affect plethodontid salamander presence and abundance.

Two surveyors conduct visual encounter surveys along a study transect. Back surveyor is lifting natural cover objects to search for plethodontid salamanders while the other is collecting soil pH, moisture, and leaf litter depth every 5 m along the transect. – Rosemary Ronca

We also collected tail tissue samples to analyze the diet of this species across our study area. Tissue samples can be used to identify isotopic signatures and give insight into prey consumption at a larger scale than stomach contents can reveal. Additionally, this method is less invasive and stressful than the typical stomach pump methods. Although, on occasion, I did have the honor of salamanders throwing up their recent meals into my hands during processing.

After spending many hours on the ground collecting population and environmental data, I went back to the lab and began the long and exciting task of analyzing my data to look for patterns in environmental predictors of Weller’s Salamander occupancy and surface activity. My study will increase our understanding of this species and allow us to better predict the needs and risks of Weller’s Salamander in the face of future threats.

One of the exciting aspects of this project has been the discovery of a unique characteristic of Weller’s Salamanders. During field surveys, we found that under certain conditions, individuals  would turn blue when removed from their substrate and exposed to the air. This has not previously been observed in individuals in the wild and has been published as a natural history note in the Society for the Study of Amphibians and Reptile’s 2023 Herpetological Review (Ronca and Winterton 2023).

Weller’s Salamander found in Ashe County, North Carolina. Upon original capture, the individual was the typical bronze color pattern, however it turned to a bright blue color within 10 minutes of being removed from substrate. – Rosemary Ronca

We also found that this species occurs across an elevational range of 700m–1600+ m. The presence of populations at lower elevations indicates that previous search efforts may have been during low activity seasons and suggests that this species may be more common than previously thought. All of our results are very exciting considering the previous lack of research into the ecological parameters of this species, with exception of the previous life history and genomics studies that have been conducted.

Graph showing the elevation of the 23 survey plots where Weller’s salamander populations were encountered. – Rosemary Ronca

With my analysis done, I have spent the last several months writing my thesis, and I completed my defense at Appalachian State University in early November, marking the end of my occupancy project. We are still waiting for the data from our stable isotope samples, which were sent to outside laboratories for processing. Once those data have been finalized and analyzed, we will have greatly increased the available information regarding Weller’s Salamander. We will have a better understanding of how this species interacts with the environment, which will be of vital importance when developing management plans in the future.



Literature Cited

Forester, B.R. 2017. Using landscape genomics to conserve adaptive capacity: A case study with a Southern Appalachian salamander. Ph.D. Dissertation, Duke University.

Organ, J.A. 1960. Studies on the life history of the salamander, Plethodon welleri. Copeia 4:287–297.

​​Ronca, R.G., and E. Winterton. 2023. Plethodon welleri (Weller’s Salamander) Color Change. Herpetological Review 54:94.