It is not known exactly how or when the European wild hog came to the park. Thirteen young boars, weighing 60 to 75 lb. apiece, first arrived in Murphy, North Carolina (approximately 40 mi. south of the park), in April 1912, destined for a game preserve. About 1920, an estimated 100 boars escaped from the preserve. According to Jones (1957), it is believed that they entered the southwestern quadrant of the park near Calderwood in the late 1940s.

Species Description:
Adult Total Length: 132-182 cm (4 1/6 ft.)
Tail: 15-30 cm (6-12 in.)
Height at Shoulder: 75-90 cm (2 1/3 ft.)
Weight: 35-200 kg (77-440 lb.)

Physical Characteristics:
The body of the European wild hog, a non-native (exotic) member of the park fauna, is built somewhat like that of a bison, being higher and heavier in the shoulder region. It is covered with thin, coarse hair. Hogs are usually black, but the tips of the guard hairs are silvery-gray or brown. A mane of long bristles may develop down the back. The upper tusks are distinctive in that they curve upward as they grow. The average weight of 181 adult males taken in the park was 197 pounds (90 kg), while the average weight of 12 adult females was 147 pounds (67 kg) (Duncan, 1974).

Habitat:
Wild hogs inhabit a variety of habitats in the park including forests and grass balds. They are found at low densities at all elevations throughout the park.

Reproduction:
Mature males are physiologically capable of breeding year-round. Females are capable of farrowing during any month but exhibited peaks in breeding and farrowing. Farrowing in the park occurs year-round with peaks in late fall-early winter and late spring-early summer. Most females farrow once a year, but when food is abundant, some sows may give birth to two litters within a 12 month period. Duncan (1974) recorded an average litter size of 3.2 (range 1 - 5). Singer et al. (1978) recorded an average pre-natal litter size of 4.75 (range 3 - 7) and an average post-natal litter size of 3.03 (range 1 - 5). Up until six months of age, young hogs possess dark longitudinal stripes on their bodies. Permanent tusks begin to grow at about one year, and sexual maturity is attained within the first year of life.

Longevity:
Nowak (1991) noted that average longevity in feral pigs is about 10 years, but some have lived as long as 27 years.

Terrestrial Ecology:
Wild hogs may be active at any time during the day or night. During the warmer months, they tend to be nocturnal in order to avoid the daytime heat. Movements are generally nomadic, and are brought about by food availability. Hogs have keen senses of smell and hearing.
Most hog observations are of single individuals or small groups usually consisting of a sow and her young. Average group size was 1.87 in a 1977 park study (Singer et al., 1978).

Wild hogs are omnivores and are seasonal in their feeding habits (Ackerman et al., 1977). In March and April, they move into the higher elevation northern hardwood forests near the state line. They move back to lower elevations in August, and feed primarily on mast, invertebrates, and small vertebrates. During the spring and early summer in the northern hardwood forest, the diet consists of springbeauty corms (Claytonia virginica) (58 percent), leaves and stems from mesic herbs (28 percent), other roots (11 percent), macroinvertebrates (2 percent), and leaves of shrubs (1 percent). Approximately 70 percent of the diet is subterranean in origin (Singer, 1981).
Invertebrates such as walking-sticks, hellgrammites, beetles, caterpillars, fly larvae, millipedes, centipedes, snails, earthworms, and crayfish are present in almost every stomach, but their volume is low. Likewise, the frequency of vertebrates is high, but the percent volume is low. Salamanders, particularly the endemic red-cheeked salamamder (Plethodon jordani), are common at the higher elevations. An average of 1.75 salamanders per stomach were recorded. Hard mast (Quercus spp., Carya spp.) normally comprises 60 to 85 percent by volume of the wild hog diet (Scott and Pelton, 1975), in late summer.
Huff (1977) reported that rooting by hogs stimulates vegetative reproduction of American beech (Fagus grandifolia), with root suckers being 4 to 44 times greater than in undisturbed plots. Studies of high elevation beech gaps in the park show that beech also respond to rooting by wild hogs with increased height growth. The shoots of beech trees in moderately and severely rooted sites were significantly longer than those for trees in lightly rooted sites (Lacki and Lancia, 1986). Bratton (1974) reported that herbaceous cover is drastically reduced in hog-disturbed sites when compared to undisturbed sites.

Diseases:
The enterococci Streptococcus faecalis and Streptococcus faecium have been recorded from fecal specimens by Mundt (1963).

Predators and Defense:
The wild hog has few predators. Bobcat (Lynx rufus) prey on young pigs, and both young and adult hogs may be preyed upon by Black bear (Ursus americanus) and Coyote (Canis latrans).

Parasites:
None recorded from the park.

Hog depredations were first noted on Gregory Bald and along the state line in 1958. In 1959, it was found that these animals were concentrated in the area between Cades Cove and Fontana Lake. Trapping began during August 1959, when an estimated 500 hogs were in the park. The estimated population increased to approximately 1500 in 1980 (Singer and Ackerman, 1981). Hog densities in 1979 in the northern hardwood forests in the western half of the park were estimated to be 79 animals per square kilometer from April to July (Singer, 1981). During the period 1959-December, 2001, 9,720 hogs were removed from the park (Stiver, pers. comm. Oct. 2001).
Hogs are now found at low densities at all elevations throughout the park. Wild hogs may be active at any time during the day or night. Most observations are of single individuals or small groups usually consisting of a sow and her young.

References:

Ackerman, B.B., M.E. Harmon, and F.J. Singer. 1978 (1977). Studies of European wild boar in the Great Smoky Mountains National Park. Part II. Seasonal food habits of European wild boar. Report for the Superintendent, Great Smoky Mountains National Pa

Duncan, R.W. 1974. Reproductive Biology of the European Wild Hog (Sus scrofa) in the Great Smoky Mountains National Park. Masters Thesis, University of Tennessee, Knoxville.

Lacki, M.J., and R.A. Lancia. 1986. Effects of Wild Pigs on Beech Growth in Great Smoky Mountains National Park. Journal of Wildlife Management 50(4): 655-659.

Singer, F.J. and B.B. Ackerman. 1981. Food Availability, Reproduction, and Condition of European Wild Boar in Great Smoky Mountains National Park. National Park Service Research/Resources Management Report 43.

Huff, M.H. 1977. The effect of the European wild boar (Sus Scrofa) on the woody vegetation of Gray Beech Forest in the Great Smoky Mountains. Great Smoky Mountains National Park, Gatlinburg, TN. Uplands Field Research Laboratory. Research/Resources M

Nowak, R.M. 1991. Walkers Mammals of the World. 5th edition. 2 volumes. Baltimore: The Johns Hopkins University Press.

Fox, J.R. and M.R. Pelton. 1977. An evaluation of control techniques for the European wild hog in the Great Smoky Mountains National Park. Pages 53-66. In: Wood, G. (editor). Research and management of wild hog populations. Baruch Forest Science Inst

Singer, F.J. 1981. Wild Pig Populations in the National Parks. Environmental Management 5(3): 263-270.

Linzey, D. W. 1995a. Mammals of Great Smoky Mountains National Park. The McDonald & Woodward Publishing Company, Inc., Blacksburg, Virginia.

Linzey, D. W. 1995b. Mammals of Great Smoky Mountains National Park-1995 Update. Journal of the Elisha Mitchell Scientific Society 111(1): 1-81.