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10-16-2004

Feral Swine Impacts on Agriculture and the Environment

Nathan W. Seward USDA-APHIS-Wildlife Services

Kurt C. VerCauteren USDA-APHIS-Wildlife Services, [email protected]

Gary W. Witmer USDA-APHIS-Wildlife Services, [email protected]

Richard M. Engeman USDA-APHIS-Wildlife Services, [email protected]

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Seward, Nathan W.; VerCauteren, Kurt C.; Witmer, Gary W.; and Engeman, Richard M., " Swine Impacts on Agriculture and the Environment" (2004). Sheep & Goat Research Journal. 12. https://digitalcommons.unl.edu/icwdmsheepgoat/12

This Article is brought to you for free and open access by the Wildlife Damage Management, Internet Center for at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Sheep & Goat Research Journal by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Feral Swine Impacts on Agriculture and the Environment

Nathan W. Seward, Kurt C. VerCauteren, Gary W. Witmer, and Richard M. Engeman

USDA/Wildlife Services, National Wildlife Research Center, 4101 LaPorte Ave., Fort Collins, CO. 80521-2154

Key Words: Depredation, Disease, including: 1) translocation to establish because of the absence of large native Eurasian , Feral Swine, Sus populations for , 2) escapees predators (e.g., mountain lion (Felis con- scrofa, Wildlife Damage Management from shooting preserves or confinement color) and (Canis lupus) over operations, 3) avoidance of capture by much of the area occupied by feral swine. Introduction domestic in free-ranging livestock In southwest Florida where feral swine operations, 4) abandonment by their and a large predator coexist, feral swine More than 30 species of exotic free- owners, and 5) dispersal from established is the most common food item (42%) in ranging have become estab- feral populations (Gipson et al., 1997; (F. c. coryi) scats (Maehr lished in the United States since Euro- Witmer et al., 2004). et al., 1990), which may suggest that the pean colonization (De Vos et al., 1956; Feral swine are the most abundant presence of a large predator helps regu- McKnight, 1964; Roots, 1976). These free-ranging, exotic ungulate in the late feral swine density and associated species often become serious economic United States (McKnight, 1964; Decker, damage. pests and can have grave consequences 1978) and have become widespread on their host environments (Cottam, because of their reproductive potential Environmental Damage and 1956; De Vos et al., 1956; Mayer and and adaptability to a wide range of habi- Brisbin, 1991). True wild pigs () tats. Like domestic swine, litter size Wildlife Depredation are not native to the United States. depends on the sow’s age, nutrition, and Only the collared (Tayassu time of year. Feral swine are capable of Environmental Damage tajacu; Tayassuidae) that inhabits the producing two litters per year with aver- Feral swine are generalists. Their southwestern and south-central parts of age litter size varying from 4.2 to 7.5 omnivorous diet allows them to utilize a the United States is native (Mayer and piglets (Taylor et al., 1998), but up to 10 variety of food sources and to thrive in a Brandt, 1982; Mayer and Wetzel, 1986). piglets can be born during ideal condi- wide range of environments. The major- Feral swine (Sus scrofa) in the United tions (Conquenot et al., 1996). Mayer ity of their diet consists of grasses, forbs, States have originated from varieties of and Brisbin (1991) and Mackey (1992) and soft and hard such as shoots, domestic swine, Eurasian wild boar, and report feral swine populations in 23 roots, tubers, fruit, and seeds. Acorn their hybrids (Jones, 1959; Wood and states. A Southeastern Cooperative Dis- (Quercus spp.) and hickory (Carya spp.) Lynn, 1977; Rary et al., 1968; Mayer and ease Study (1994) and Nettles (1997) nuts are two important food items that Brisbin, 1991). Domestic swine were point out an additional 16 states with feral swine use seasonally (Mungall introduced to the United States as early feral swine populations. An estimated 2001) and may lead to competition with as 750-1000 A.D. during the settlement population of 4 million feral swine - other wildlife (Yarrow and Kroll, 1989). of the Hawaiian Islands (Towne and rently occur in the United States Feral swine also eat a variety of inverte- Wentworth, 1950; Joesting, 1972; Smith (Pimentel et al., 2000) with the largest brates including earthworms, leeches, and Diong, 1977). Christopher Colum- populations inhabiting (1 to 1.5 grasshoppers, centipedes, beetles, and bus introduced domestic swine to the million; Pimentel et al., 2000), Florida other arthropods. As a predator, feral during the 1400s, where (>500,000; Layne, 1997), Hawaii swine eat salamanders, frogs, fish, crabs, they proliferated and became pests. In (80,000; Mayer and Brisbin, 1991), and snakes, turtles, , muskrats (Onda- the 1500s, Spanish explorers, such as California (70,000; Barrett, 1993). Since tra zibethicus), and chicks of ground- DeSoto and Cortez, were the first to 1965, feral swine have expanded their nesting birds, white-tailed fawns bring domestic swine to the United range from 15 (26%) to 45 (78%) of the (Odocoileus virginianus) (Hellgren, States mainland (Towne and Went- 58 California counties (Frederick, 1998). 1993), and livestock. Feral swine must worth, 1950; Beldon and Frankenberger, Feral swine populations continue to forage almost continuously because their 1977). By the 1960s, domestic swine and increase (Gipson et al., 1997) because simple stomach is not as efficient as a Eurasian wild boar were established in they possess the greatest reproductive ruminant’s multi-chambered digestive >20 states (McKnight, 1964). Swine potential of all free-ranging, large mam- system — hence the expressions “as introductions have intentionally or acci- mals in the United States (Wood and greedy as a ” and “eats like a pig.” dentally occurred by a variety of means, Barrett, 1979; Hellgren, 1999) and Feral swine negatively impact natu-

34 Sheep & Goat Research Journal, Volume 19, 2004 ral plant communities (Bratton, 1975; dation may negatively affect bobwhite to increase as feral swine flourish and Wood and Barrett, 1979; Stone and quail (Colinus virginianus) and wild encroach wildlife habitat. Keith, 1987) and may seriously impact (Meleagris gallopavo) nest success agricultural ecosystems (Singer et al., (Synatzske, 1979). Tolleson et al. (1993) Livestock Depredation 1982). Feral swine rooting activity, dig- constructed 192 simulated quail nests in ging for food with their snout, loosens Texas and reported that feral swine was Feral swine are well documented as the soil and accelerates erosion, sets the most common predator (28%) of significant predators of lambs (Ovis aries) back plant succession, reduces earth- simulated nests. They concluded feral in (Moule, 1954; Rowley, worm activity, and exacerbates exotic swine could have detrimental effects on 1970, Pavlov et al., 1981, Choquenot et plant invasion (Mungall, 2001). Damage bobwhite quail populations depending al., 1997) where 4 to 20 million feral from rooting, trampling, and compaction upon the density of quail and feral swine, swine exist (Emmerson and McCulloch, directly and indirectly impacts plant quail nesting cover, and quantity and 1994; Pimentel et al., 2000). Feral swine regeneration, plant community structure diversity of other swine food sources. prey on a variety of other livestock (Bratton, 1975), soil properties (Lacki On some southeastern U.S. beaches, including goats (Capra hircus), newborn and Lancia, 1983), nutrient cycling feral swine have become significant cattle (Bos taurus), and exotic . (Tate, 1984), and water infiltration predators of marine turtle nests by exca- matter typically makes up only a (Mungall, 2001). Rooting and inciden- vating and feeding on the eggs (Stancyk, small percentage of their diet, but con- tal damage may give exotic plants an 1982; Lewis et al., 1996). Feral swine siderable economic loss can occur from ecological advantage over native plants seriously threaten the nesting success of livestock depredation. In Australia, the (Howe and Bratton, 1976) because several threatened and endangered greatest losses occur in sheep (wool and exotic plants are typically better adapted marine turtles including: the loggerhead meat loss) and cattle production (Tis- at colonizing disturbed areas. Addition- (Caretta caretta) (federal; threatened); dell, 1991). In the semi-arid rangelands ally, feral swine may help spread root-rot green (Chelonia mydas) (federal; endan- of Australia, losses of newborn lambs fungus (Phytophthora cinnamomi), which gered); leatherback (Dermochelys cori- from feral swine predation have been as causes disease in native vegetation acea) (federal; endangered); hawksbill high as 32% (Plant et al., 1978), with a (Kliejunas and Ko, 1976). (Eretmochelys imbricata) (federal; endan- multiple-year average loss of 19% Habitat damage by feral swine is gered); and the Kemp’s ridley (Lepi- (Pavlov et al., 1981). Choquenot et al. most pronounced in wet environments dochelys kempii) (federal; endangered), (1997) found that the rate of lamb pre- (e.g., Choquenot et al., 1996; Engeman destroying up to 80% of nests in some dation increased with feral swine density, et al., 2004). Exposed marsh shoreline is regions of Florida (USDA, 2002). It has until reaching a maximum of 29% at a particularly susceptible to damage become critical to monitor and manage density of 4 to 8 pigs/km2. Predation typ- because the shoreline and shallower nest predation to ensure the existence of ically occurs on lambing or calving water is typically dominated by shrubs these threatened and endangered turtles. grounds, possibly because of the attrac- and herbs, which are attractive forage USDA/Wildlife Services (WS) is work- tion of afterbirth and fetal tissue (Wade (Engeman et al., 2003). Feral swine also ing with various state and federal agen- and Bowns 1985; Beach, 1993). Occa- use upland habitats and have been docu- cies to reduce turtle nest predation by sionally, livestock giving birth are killed mented impacting longleaf pine (Pinus protecting nests with portable fences and and fed upon (Wade and Bowns, 1985). palustris) regeneration (Lipscomb, 1989) reducing feral swine densities through Predation occurs throughout the age and southern hardwood forest composi- cage trapping and culling. classes for sheep and goats, but newborn tion (Wood and Lynn, 1977; Lacki and or immature are usually targeted Lancia, 1986). Livestock Depredation and (Beach, 1993). In fact, feral swine preyed upon twin lambs on average 5 to Wildlife Depredation Agricultural Crop Damage 6 times more than single lambs Feral swine impact native wildlife in Shortly after (Choquenot et al., 1997). This is likely a variety of ways, depending upon the introduced swine to the West Indies, attributed to twin lambs being smaller habitat, density of feral swine, and other feral swine depredated cattle (Ens- and weaker than their single counter- extraneous factors. About 400 of the 958 minger, 1961) and consumed agricul- parts (Alexander, 1984) and the divided wildlife species listed as threatened or tural crops such as maize and sugar cane vigilance of their mother. Feral swine endangered under the Endangered (Donkin, 1985). Frederick (1998) sur- have been observed to disrupt flocks Species Act are considered to be at risk veyed all 58 county agricultural commis- 78% of the occasions when within 100 primarily because of competition or pre- sioners in California and reported m and caught lambs during 24% of dation by non-indigenous species $1,731,920 in feral swine damage. This chases (Pavlov and Hone, 1982). Feral (Nature Conservancy, 1996; Wilcove et figure is likely underestimated because swine predation may be difficult to doc- al., 1998; Pimentel et al., 2002). In only 69% of county agricultural commis- ument because the entire carcass is typi- Florida, feral swine have contributed to sioners responded, and the exact number cally consumed, leaving little evidence. the decline of at least 22 plant species and monetary value of damaged Additionally, feral swine will scavenge and 4 species of amphibians listed as resources was conservatively estimated dead animals including other swine car- rare, threatened, endangered, or of spe- (Frederick, 1998). Livestock and wildlife casses (Hanson and Karstad, 1959; cial concern (USDA, 2002). In the depredation and agricultural and envi- Nichols, 1962). Therefore, predation , feral swine pre- ronmental damage will likely continue may be mistaken as low productivity in

Sheep & Goat Research Journal, Volume 19, 2004 35 the herd, or vice-versa, when scavenged to feral swine in Texas, with an esti- species of ticks opportunistically infect stillborns and aborted fetuses are mis- mated value of $63,000 (Rollins, 1993). and feed on humans. The diseases of taken as cases of depredation. Barrett and Birmingham (1994) reported most concern to the livestock industry Feral swine usually follow a charac- 1,473 sheep, goats, and exotic game ani- include pseudorabies, swine brucellosis, teristic feeding pattern that makes iden- mals were killed by feral swine in Texas bovine tuberculosis, leptospirosis, and tification of depredation possible if the and California in 1991. In a more recent vesicular stomatitis (Becker et al., 1978; entire carcass is not consumed (Pavlov survey, 23% of county agricultural com- Williams and Barker, 2001). These and and Hone, 1982). Death typically occurs missioners in California reported live- the possibility of an exotic disease out- by biting and crushing the skull or neck stock depredation by feral swine (Freder- break, such as foot-and-mouth disease, a (Frederick, 1998). A good indicator of ick, 1998); total economic loss was not contagious viral disease of ungulates feral swine predation is that the prey’s estimated. Texas produces 1.1 million (e.g., pigs, sheep, cattle, goats, and deer) carcass will be skinned out with the goats annually, about 90% of the goats (Pech and McIlroy, 1990), or classic rumen or stomach contents consumed raised in the United States (Scrivner et swine fever (a contagious viral disease of (Wade and Bowns, 1985). Feral swine al., 1985), and Pearson (1986) reported wild and domestic swine), could have tracks are distinct and may help decipher that predators killed 18% of adults and serious repercussions for livestock indus- cause of mortality when the soil and 34% of kids. The number of goats lost to tries (Hone et al., 1992). On the other nearby vegetation have been disturbed. feral swine predation is unknown, but is hand, feral swine may serve as a surveil- Feral swine cause serious economic likely substantial (>$1 million) consid- lance tool for the early detection of loss to the livestock industry, although ering $5.7 million was lost to in exotic diseases (Mason and Fleming, exact numbers and values are largely the United States in 1990 (NASS 1999; Witmer et al., 2004). These poten- unknown. This may be caused by 1991). Additionally in 1990, combined tial health aspects should be kept in misidentification of the cause of preda- sheep and lamb losses from coyotes were mind when considering feral swine range tion. For example, signs of (Canis valued at $18.3 million in the United expansion, translocation (Forrester, latrans) and feral swine predation appear States (NASS, 1991). Where practical, 1991), and tolerance around livestock very similar; therefore cases reported as ranchers should closely monitor live- operations. coyote predation may actually be feral stock and confine pregnant animals to swine. This is especially plausible in protected areas during calving and lamb- Crop Damage Texas, where high densities of coyotes ing seasons to reduce susceptibility to and feral swine exist and target newborn predation. An understanding of field Feral swine damage pasture and animals. Coyotes typically attack sheep sign and different behavioral cues can agricultural crops by consumption, root- and goats with a bite to the throat, caus- help determine cause of mortality and ing, digging, and trampling. In Aus- ing death from suffocation and shock, the impact of feral swine predation. tralia, feral swine cause considerable then feed on their prey (Wade and agricultural crop damage with >$100 Bowns, 1985) starting at the flank or just Feral Swine and Disease million lost annually (Choquenot et al., behind the ribcage. Coyotes typically 1996). The greatest losses occurred in leave splintered bones, chewed ribs, and Annual sales in the United wheat, sorghum, barley, oilseeds, sugar scattered pieces of skin, fur, tendons, and States exceed $11 billion with retail cane, oats, and maize, in that order (Tis- bones (Wade and Bowns, 1985). Con- sales exceeding $34 billion (Witmer et dell, 1991). In the United States, feral versely, black bear (Ursus americanus) al., 2004). Therefore, there is concern swine damage $800 million in agricul- normally do not consume the rumen and relative to the role feral swine could pose tural crops each year, assuming that 4 its contents, but the carcass will appear to the pork industry as a reservoir for dis- million feral swine inhabit the United skinned out (Wade and Bowns, 1985). ease. However, only 26% of Texas agri- States and cause $200 worth of damage Black bears usually do not scatter their cultural extension agents were con- per pig (Pimentel et al., 2002). This prey, and the hide and skeleton will be cerned about disease transmission to estimate is likely very conservative mostly intact. Large claw marks across livestock (Rollins, 1993). Feral swine because it does not consider livestock the shoulders and back may provide can harbor at least 30 significant viral predation, disease transmission, or envi- additional clues. and bacteriological diseases (Williams ronmental degradation. The annual economic loss from feral and Barker, 2001) and feral swine in In Texas, the most common com- swine predation in the United States is Florida have been documented to have plaint or concern (75%) in a survey con- unknown; however feral swine predation as many as 45 different parasites and ducted by Rollins (1993) was damage to on livestock in the United States does infectious diseases (Forrester, 1991). agricultural crops including hay, small not appear to be as prevalent as in Aus- These include 37 parasites (12 proto- grains (milo, rice, and wheat), corn, and tralia, where >$80 million is lost annu- zoans, 17 nematodes, 1 acanthocepha- peanuts. Other crops affected were veg- ally (Emmerson and McCulloch, 1994). lan, 1 sucking louse, 4 ticks, and 2 etables, watermelons, soybeans, cotton, In Texas, Rollins (1993) reported that mites), 7 bacteria, and 1 virus. Eight of orchards, horticultural crops, and conifer 33% of county agricultural agents listed these parasitic and infectious diseases seedlings. Seventy-two percent of sur- livestock depredation by feral swine as a can infect humans (brucellosis, lep- veyed extension agents reported addi- problem with losses directed towards tospirosis, salmonellosis, toxoplasmosis, tional damage to ranch facilities (e.g., sheep and goats. In 1990, 1,243 sheep balantidiasis, trichinosis, trichostrongy- fences, water supply, irrigation ditches, and goats were documented as being lost losis, and sarcoptic mange). All four and guzzlers).

36 Sheep & Goat Research Journal, Volume 19, 2004 Population Control proof, but they can significantly reduce Edwards-Jones, 1997; Leaper et al., and Management feral swine movement into protected 1999) and allow range expansion. Some areas. Wire mesh fencing or adding an individuals, mostly feral swine hunters No panacea for feral swine control, electrified wire to an established fence 15 and landowners that generate revenue management, or eradication currently to 20 cm off the ground appear to be the from hunting leases, encourage feral exists (Choquenot et al., 1996). In most most effective means of excluding feral swine and consider them a desirable big states feral swine are unprotected or clas- swine (Hone and Atkinson, 1983). How- game species. In most states with large sified as an agricultural pest, therefore ever, due to the associated cost of these populations (e.g., Texas, Florida, Califor- hunting methods are liberal and swine control measures, agricultural producers nia, and Hawaii), feral swine are consid- can be harvested throughout the year. must weigh the cost of taking precaution ered a big game species and year-long States where feral swine are classified as to their expected loss to determine if hunting seasons have been established to game animals rely on hunter harvest to action is cost-effective. An integrated “control” numbers. In Texas, Rollins control or regulate swine populations; approach may be more feasible and may (1993) regarded feral swine hunting as a however, sport hunting has had negligi- help alleviate feral swine recognition and sport for locals more so than nonresi- ble effects on swine population manage- avoidance of specific control practices dents with an average cost of $169 per ment (Barrett and Stone, 1993). Feral (Choquenot et al., 1996). hunter. However, this may be changing; swine can be controlled by several tech- One of the greatest needs for feral in 1998 the Texas Parks and Wildlife niques including shooting, trapping, and, swine management is a practical means Department generated over $1 million in overseas locations, with toxicant bait- for indexing populations (Choquenot et from the sale of 30,512 hog permits to ing (Tisdell, 1982). In Australia, toxicant al., 1996). Knowledge of relative swine nonresidents (Chambers, 1999). Hunt- baiting [e.g., sodium monofluoroacetate population abundance and spatial distri- ing may serve to alleviate disease trans- (Compound 1080), ] has been bution is valuable for timing control pro- mission and predation by reducing the used to reduce feral swine populations in grams, optimally locating control sites, number of feral swine at the livestock some areas by 58 to 73% depending upon and evaluating control efficacy. A vari- interface. Ranchers and farmers should the length of the poisoning campaign ety of methods have been applied to esti- be encouraged to hunt feral swine, grant (Hone and Pederson, 1980; Hone, 1983; mate absolute abundance of feral swine, hunting permission, and participate in Pech and Hone, 1988). Careful consider- though they often require many state hunter access programs. ation and monitoring must be applied resources and produce mixed results Although feral swine hunting gen- when using toxicants because other non- (Choquenot et al., 1996). Assessments erates income for some, the damage to target species may be harmed (Stone et of populations can be done by directly private and public property and natural al., 1988). Frightening devices are inef- estimating population density through resources is hardly justifiable. Ranchers fective and no repellents or toxicants are line-transect (e.g., Burnham et al., 1980) and farmers should understand the registered for feral swine use in the or mark-recapture estimation (e.g., Otis potential risks and have cost-effective United States (Barrett and Birmingham, et al., 1978). An alternative is to calcu- means available to them for feral swine 1994). Other lethal means for eradica- late an index reflective of population control. In areas where feral swine pose a tion include aerial hunting with helicop- abundance (e.g., Caughley, 1977). Enge- threat to natural resources, most conser- ters, hunting with dogs, or shooting at man et al. (2001) recently evaluated a vation organizations promote the eradi- night over bait. Saunders and Bryant passive-tracking method in Florida to cation or reduction of feral swine popu- (1987) used aerial shooting over five days index the relative abundance and distri- lations. Until a paradigm shift occurs to reduce a population by 80%. Hunting bution of feral swine in an area and to and society understands that the nega- with dogs can also be effective at reduc- evaluate the impact of control programs. tive impacts feral swine cause outweigh ing feral swine populations in local areas The technique is easy to use and allows any immediate or potential benefits, (Barrett and Birmingham, 1994). Trap- managers to index feral swine density some current conservation strategies for ping and snaring followed by euthanasia around agricultural operations. Knowl- native wildlife and maintenance of dis- can also help reduce swine density and edge of feral swine density will aid in ease-free, domestic-swine populations nuisance animals. Trapping with corral making decisions about whether control will be at risk. traps and portable drop-gate traps can be measures are warranted. If density is low, In the United States, ranchers and effective, but efficacy varies seasonally then the associated risk of depredation farmers operating in feral swine-occu- with production of natural food sources may be acceptable and no control meas- pied areas need more information (e.g., acorns) (Barrett and Birmingham, ures may be necessary. However, if feral regarding feral swine damage and means 1994). Leg snares can be effective, but swine density is high, then it may be to alleviate potential losses. Research is should be implemented with caution in beneficial to take precaution and reduce needed to determine the rate of preda- areas where livestock, deer, or other non- the threat of damage. tion relative to feral swine density, assess target animals may be present. Access the economic loss caused by feral swine points such as fence under-passes or pen Discussion predation, quantify the rate of disease entrances not used by non-target animals transmission to domesticated livestock, are ideal. Other control measures to alle- Despite the negative impacts feral and to develop economical means to viate damage include excluding feral swine have on agriculture and the envi- alleviate feral swine damage. Current swine with wire mesh fencing or electric ronment, humans continue to introduce damage management techniques in the fence. No fence design is completely pig- feral swine to new areas (Howells and United States include fencing, snares,

Sheep & Goat Research Journal, Volume 19, 2004 37 cage traps, and various methods of hunt- Larsen, editors. Prevention and Decker, E. 1978. Exotics. Pages 249-256 ing. In Australia, the use of aerially Control of Wildlife Damage. Coop- in J. L. Schmidt and D. L. Gilbert, delivered toxic bait is legal, and it is the erative Extension Service, Univer- editors. Big game of North America: most efficient means of quickly reducing sity of Nebraska, Lincoln, NE, Ecology and management. Stack- feral swine numbers. Resource manage- USA. pole Books, Harrisburg, PA, USA. ment agencies in the United States Beach, R. 1993. Depredation problems Donkin, R. A. 1985. The peccary - with should consider following Australia’s involving feral hogs. Pages 67-75 in observations on the introduction of lead and manifesting a management plan C. W. Hanselka and J. F. Caden- pigs to the . Transactions for the eradication of feral swine in areas head, editors. Feral swine: A com- of the American Philosophical that have the potential to be exposed to pendium for resource managers. Society 75(5): 1-152. exotic livestock diseases. This would Texas Agricultural Extension Ser- Engeman, R. M., B. Constantin, M. Nel- vice, Kerrville, TX, USA. son, J. Woolard, and J. Bourassa. likely require the registration and Becker, H. N., R. C. Belden, T. Brevault, 2001. Monitoring changes in feral approval of a toxicant and bait delivery M. J. Burridge, W. B. Frankenberger, swine population and spatial distri- system that targets feral swine with min- and P. Nicoletti. 1978. Brucellosis in bution of activity. Environmental imal impact on non-target species and feral swine in Florida. Journal of the Conservation 28: 235-240. the environment. As Tisdell (1991:168) American Veterinary Medical Asso- Engeman, R. M., H. T. Smith, R. G. Sev- stated, “the question has been raised ciation 173: 1181-1182. erson, M. M. Severson, S. A. Shwiff, whether feral swine should be managed Beldon, R. C. and W. G. Frankenberger. B. Constantin, and D. Griffin. 2003. on a sustainable yield basis, with an erad- 1977. Management of feral hogs in Amount and economic valuation of ication strategy pursued only if an exotic Florida — past, present, and future. feral hog damage to a unique basin livestock disease, such as foot-and- Pages 5-10 in G. W. Wood, editor. marsh wetland in Florida. Florida mouth, be accidentally introduced.” Research and management of wild Park Service, 2003 “Partnership” This statement is very reactionary; we hog populations. Clemson Univer- Technical Report. Tallahassee, FL. must remember that feral swine are an sity, Georgetown, SC, USA. 5p. exotic species and pose a significant Bratton, S. P. 1975. The effects of the Engeman, R. M., H. T. Smith, S. A. threat to agriculture and the environ- European wild boar, Sus scrofa, on Shwiff, B. Constantin, M. Nelson, ment. 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