Hog Wild: Using GIS to Examine 26 Years 19762001 of

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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 1940s, 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 (124,000) 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.