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Organismic & Evolutionary Biology
Master of Science (M.S.)
Year Degree Awarded
Month Degree Awarded
four-toed salamander, Hemidactylium scutatum, habitat use, movement, CART, model
Understanding the movement phenology of the four-toed salamander (Hemidactylium scutatum) is essential to guide management practices. I examined the relationship between environmental variables and the directionality, timing, and magnitude of four-toed salamander movements at two locations in eastern Massachusetts. Four-toed salamanders move from upland habitats to wetland areas in early spring and move away from wetlands in late spring. Adult movements increased with more precipitation and less moon light. Juvenile movements were similarly affected, and in addition they were more likely to move when temperatures were warm and days long. My results can be used to implement management strategies aimed at reducing human-related impacts on migrating four-toed salamanders (e.g., road closures to reduce road mortality).
In addition, I developed and evaluated the accuracy of classification and regression tree (CART) models at multiple spatial scales to predict suitable habitat and potential species occurrences of the four-toed salamander (Hemidactylium scutatum) in Massachusetts. I analyzed four-toed salamander Element Occurrence (EO) observations reported during 1990-2009 in response to fifteen environmental predictor variables at six different local and landscape-scales. The landscape-scale model measured at 2000 m was most successful at predicting four-toed salamander habitat. It correctly classified 92.4% of the training data and 87.7% of the verification data. When the 2000 m model was applied statewide, 30,195 wetlands were determined to be potentially suitable habitat for the four-toed salamander. The results of this study confirm the potential and value of classification and regression tree models for identifying potential habitat for rare or cryptic species.
Paul R Sievert