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Since a considerable amount of time and money are spent on the control program, officials have a vested interest in efficiently removing hogs from GSMNP. I assisted in this effort by using removal locations to develop a spatial model for the population's niche. The form of the harvest data lends itself to a presence-only distribution modeling method such as an environmental niche factor analysis (ENFA). This approach uses the concepts of marginality and specialization to quantify a species’ niche by relating ecogeographic data to known presence locations. Marginality determines the types of conditions the species prefers and specialization measures how much the species deviates from their preferences.
In order to measure these correlated and multi-variable dependent values, ENFA leverages the theory of principal component analysis in an innovative way to produce uncorrelated environmental predictors that quantify the niche. Ecogeographic preferences were then projected across the Park to create two maps relevant to hog presence.
The first map categorizes the environmental conditions at each location in GSMNP as one of five options ranging from unsuitable to most suitable for hogs. The second map highlights places within the most suitable locations where one would be most likely to encounter a hog. Results were validated using a predicted-to-expected ratio and a continuous Boyce index. This research provided the first scientific analysis of hog hunting locations and illustrates areas where hogs can be efficiently removed from GSMNP.