Invasive Species Poster Wild Boars

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“Hog Wild: Using GIS to Examine 26 Years (1976-2001) of Wildlife Management Efforts to Control the Invasive European Wild Boar (Sus scrofa Linneaus) in the Great Smoky Mountains National Park” The University of Tennessee at Chattanooga Robert D. Keller, Ph.D, R. Gary Litchford, Ph.D, James C. Brinson, Andrew M. Carroll, Jason M. Houck, H. Ford Mauney, and M. Taylor McDonald

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ABSTRACT The University of Tennessee at Chattanooga (UTC) geographic information systems (GIS) research laboratory, working in tandem with wildlife management officers from the Great Smoky Mountains National Park (GSMNP), has begun to use GIS to examine twenty-six years of park service efforts to control populations of an invasive species, the exotic European wild boar (Sus scrofa Linneaus).

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INTRODUCTION Approximately twenty-two years after the wild boars were introduced into Graham County, North Carolina, the Great Smoky Mountains National Park was officially established on the North Carolina/Tennessee border (Howe et al. 1981). The park lies in the southern extension of the Appalachian Mountains approximately thirty miles to the northeast of the initial wild boar introduction. As a national park, the Great Smoky Mountains National Park was created “to preserve, maintain, and restore natural ecosystems and natural processes in as nearly a pristine condition as possible” (Executive Order 11,987). Impact by the advancing wild boar population on the newly formed Great Smoky Mountains National Park seemed inevitable. By the late 1940’s, the exotic European wild boars began to make an appearance in the southwestern extremes of the park area, and the impact of these animals on the native flora and fauna of the park was immediately evident. During their normal feeding behavior (called rooting), wild boars disturb the soil. Hog rooting destroys vegetation, reduces small mammal refugia, and enhances the deleterious effects of erosion. By the late 1950's, control efforts were underway with the displacement and/or removal of approximately sixty wild boars per year (Mayer and Brisban 1991). Current control efforts remove approximately three hundred wild boars per year (B. Stiver pers. comm.). Despite current and historical control efforts, the wild boars remain present in the Great Smoky Mountains National Park and have been recognized as a major management problem.

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METHODS AND MATERIALS A total of 8,521 “animal take” records were compiled, representing approximately 376 tons of wild boar taken over a twenty-six year span. Of the 8,521 records, only 612 were properly geo-referenced using Universal Transverse Mercator (UTM) coordinates. The remaining 7,909 had to be spatially referenced in a post-hoc fashion using 2001 National Geographic Holdings topographical maps and written descriptions of locations of “animal take”. The “animal take” records consisted of location of take, date of take, capture type, sex of animal, age/class distribution (piglet, juvenile, adult), moon phase, approximate weight of the animal taken, and identity of the control officer. Locations of “animal take” are displayed in ArcGIS Desktop 8.1.2 using 7.5 minute United States Geological Service (USGS) topographical maps (1:24,000) projected in UTM Zone 17 NAD 1927 format (Fig. 1). The highest densities of historical “animal take” are portrayed in dark red with decreasing densities ranging from lighter red, to blue, to tan, to white.

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Fig. 1. Portrayal of 26 years of hog control efforts in the Great Smoky Mountains National Park

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RESULTS Mapping the hog control data shows that successful “animal take” locations over the twenty-six year time span appear to have a clumped geographic distribution. Extremely high kill densities appear only in a few “hot spots” – the most hunted areas of the park. Most “hot spots” are clustered around 1) paved roads, 2) the Appalachian Trail, or 3) backcountry “hog hunter” shelters. Many other less accessible areas of the park are shown to be under-hunted and appear on the map as large expanses of tan or white. Early researchers had hypothesized that if hog control efforts were not uniformly distributed throughout the GSMNP that efforts to control a population of invasive wild boars may actually stimulate population growth (Tate 1983). This mapping endeavor shows that the hog control effort through 2001 has had highly uneven kill success throughout the park.

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FUTURE IMPROVEMENTS Beginning in January of 2002, GSMNP wildlife control officers were outfitted with Garmin III Plus global positioning system(GPS) units in order to properly catalog future “animal take” records. Any permanent locations of importance (hog hunter shelters, bait stations, hog traps, etc.) will also be recorded using GPS. Wildlife control officers Kim Delozier and Bill Stiver will be combining the GPS data with GIS support provided by UTC personnel to implement a more comprehensive and effective hog control effort in the park.

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ACKNOWLEDGEMENTS Funding for this project was provided by the National Biological Information Infrastructure (NBII). Special thanks to Great Smoky Mountains National Park wildlife management officers Kim Delozier and Bill Stiver for their assistance and insight. Literature Cited Howe, T. D., Singer, F. J. and B.B. Ackerman. 1981. Forage relationships of European wild boar invading northern hardwood forest. Journal of Wildlife Management, 45 (3): 748-753. Mayer, J.J. and I.L. Brisban. 1991. Wild Pigs of the United States: Their history, morphology, and current status. The University of Georgia Press. Athens, GA. Tate, J. 1983. Techniques for controlling wild hogs in Great Smoky Mountains National Park: Proceedings of a workshop, November 29-30. Research/Resources Management Report SER-72. 87 pp.