Date of Award
Master of Science (MS)
Forestry and Environmental Conservation
Catherine M. Bodinof Jachowski
Todd W. Pierson
Patch-nosed Salamanders (Urspelerpes brucei) are tiny (25.76 ± 0.17 mm [SE] snout-vent length) plethodontids endemic to headwater streams in a small (29 km2 at the time of our study) geographic region of northeast Georgia (GA) and northwest South Carolina (SC). Due to its secretive nature and recent discovery (2007), little is known about U. bruceihabitat, life history, or potential threats. Though environmental DNA (eDNA), aquatic leaf litter bags, and opportunistic active searches are successful detection techniques for U. brucei, and other factors influencing detection are unknown. Additionally, while occupied U. brucei streams have been characterized as shallow and steep-walled, previous work has not identified factors that influence U. brucei microhabitat use among patches within a single occupied stream. In Chapter 1, we applied six survey methods in three streams where U. brucei occur using a randomized complete block design and replicated each survey technique six times between August 2021 and June 2022. We used occupancy models to simultaneously investigate factors influencing U. brucei occupancy within a 5-m stream segment while estimating detection probability for each survey method and across a range of other survey-specific conditions. We found aquatic and terrestrial area-unconstrained surveys were at least 3.25 times better at detecting U. brucei than aquatic area-constrained surveys, while cloudless skies, recent rainfall amounts (> 5 cm in the previous week), and higher soil temperatures (≥ 20 °C) were positively associated with detection. Chapter 2 describes our finer scale analysis where we used occupancy models to investigate factors influencing U. brucei microhabitat use at the scale of a 31 x 31 cm patch. Notably, we used a subset of field data collected in Chapter 1 for analysis in Chapter 2. We found leaf litter accumulationrepresented the primary driver of microhabitat use for both U. brucei larvae and adults. Specifically, for larvae, shallow stream depths (≤ 4 mm) and deep leaf litter (≥ 70 mm) was the best predictor for microhabitat use, whereas adults had the highest probability of using microhabitat consisting of leaf litter depths ≥ 111 mm. Collectively, our findings emphasize the success of area-unconstrained surveys and leaf litter bag surveys under ideal weather conditions when detecting both larval and adult U. brucei. Additionally, we highlight how U. brucei distribution within streams can be highly variable, presumably because of variation in stream depth and leaf litter depth. We also found U. brucei seem to be rarer in SC relative to GA for reasons we do not fully understand. Moreover, our findings advance our understanding of effective U. brucei survey protocols, identifying microhabitat use, and baseline occupancy estimates that can be used to inform future research aiming to ascertain population demographics, further investigate distribution within occupied streams, and prioritize essential habitat to protect.
Anderson, Chelsea, "Detection And Microhabitat Use Of The Cryptic Patch-nosed Salamander (Urspelerpes Brucei) In Three Occupied Streams" (2023). All Theses. 4004.