Feral Hogs: The Florida Experience

ROBERT C. BELDEN, Florida Game and Fresh Water Fish Commission,
Wildlife Research Laboratory, 4005 S. Main Street,
Gainesville, FL 32601

Florida’s feral hog (Sus scrofa) population is second in the United States only to that of Texas. Feral hogs are found throughout the state in a variety of habitats from the southern Everglades to the northern hills of the Panhandle. The history of feral hogs in Florida is described in Belden and Frankenberger (1977 and 1989) and in Mayer and Brisbin (1991).

Distribution and Abundance

Wild hogs are reported in all 67 counties (Figure 1). However, large portions of 12 counties with extensive agricultural operations and urbanization lack wild hog populations. The area of high hog populations in counties immediately north and west of Lake Okeechobee contain many large, private landholdings where public access is limited. Habitat conditions in these counties are favorable for hogs. The flatwoods community predominates and is interspersed with freshwater marshes, ponds, sloughs, and cabbage palm (Sabal palmetto) hammocks. Most low and medium level populations occur where habitat quality is limited. In some areas trapping, sport hunting, and agricultural depredation control measures may have suppressed populations.

Management

Wild hogs were first declared game animals in Florida on the J.W. Corbett, Eglin Field, and the Everglades Wildlife Management Areas (WMAs) during 1956. They are now game animals on 45 WMAs; 2 Wildlife and Environmental Areas; and in portions of Collier, Dade, and Monroe Counties. Public hog hunting is also allowed on the 3 National Forests in Florida although wild hogs have not been declared game animals on these lands due to Forest Service policy which recognizes them as domestic livestock. Although hunting regulations are specific for each area, in general, wild hogs may be taken only during the open deer season, generally mid-November through the first weekend after New Years, either sex is legal, and hogs less than 15 inches high at the shoulder are protected. The bag limit is 1 per day with no season limit. Outside of WMAs, wild hogs are considered domestic livestock and are the property of the landowner upon whose land they occur. With landowner permission on private property, there is no closed season, bag limit, or size limit.

Based on a questionnaire survey in 1980-81, approximately 17.5% of all licensed hunters hunted hogs. This amounted to 45,000 residents and 600 non-residents; the non-residents came from 26 states. Today, the proportion of license holders hunting feral swine has increased to 25%, but the total number of hunters has declined, resulting in very little change in the absolute numbers of people hunting wild hogs (Degner 1989).

The 1980-81 survey indicated that hunters made 386,000 hunting trips and spent 522,000 man-days hunting wild hogs. Nearly 21,000 hunters killed at least one hog. These hunters represented 46% of the residents and 28% of the non-residents (nearly 103,000 hogs were killed) (Degner 1989).

The major difficulty encountered by the Florida Game and Fresh Water Fish Commission (FGFWFC) in its attempt to manage wild hogs on many wildlife management areas has been the inability to maintain hog populations in the face of heavy hunting without re-stocking. During the 1960′s and 1970′s, over 4,500 hogs were relocated (Belden and Frankenberger 1977). This relocation effort developed into a fairly large scale operation with 200-300 hogs being relocated each year.

The FGFWFC has, in the past, entered into various agreements with governmental and private landowners who did not permit hunting or who otherwise had surplus wild hogs to trap the animals and transfer them to areas where public hunting was allowed. This was the main approach used for many years in an attempt to eliminant wild hogs from state park lands. However, the Florida Department of Natural Resources (FDNR) presently feels that the trapping program did very little to accomplish its objective of eliminating wild hogs and merely served as a source of wild hogs for hunting (Belden and Frankenberger 1977). Particular problems encountered were that some hogs became trap-shy, trappers tended not to remove breeding females, and quarantine procedures were not followed (Thompson 1977). Also, in one case, a comparison of the success rate for live trapping versus shooting revealed that baited live traps averaged only one hog per 18 trap-nights over the sample period, whereas night shooting at baited stations yielded one hog per 4 hours of hunting effort (Brown 1985). Therefore, FDNR believes that hunting may be a better means to control wild hogs on certain state parks. This substantially reduces the availability of wild hogs for restocking purposes.

While the past trapping program was successful to a degree, FGFWFC did not have a coordinated program to assure that huntable wild hog populations were maintained on the WMAs. In many cases, over harvest of hogs occurred because hunting regulations were not sufficiently restrictive to prevent it. As a result of annual over-harvest, hog management on several areas (Corbett, Everglades, etc.) developed into a put-and-take system which depended on the expensive annual restocking effort to assure the continuance of huntable hog populations (Memorandum dated 1976 from Fred W. Stanberry to Commissioners and Commission Staff, FGFWFC, Tallahassee).

Another problem encountered was that release areas were sometimes determined more by distance, available time, and manpower than a real need for more hogs. Therefore, some of the management areas were continually stocked to the point that they were probably overpopulated (Frank Montalbano 1977, FGFWFC, pers. commun.). Also, areas which simply did not have sufficient habitat to support a viable population of wild hogs were stocked (Memorandum dated 1976 from Fred W. Stanberry to Commissioners and Commission Staff, FGFWFC, Tallahassee). Experience showed that where the habitat in the release area was largely unsuitable, hogs released even within a few days of the hunting season would widely disperse and not be available to hunters (Larry Campbell 1977, FGFWFC, pers. commun.). The number of stocked hogs harvested was found to be indirectly correlated to the number of days between release and the onset of hunting season (Bowman and Horne 1982).

Several regulations have been tried in an attempt to prevent depletion of hog populations, including: (1) shortening the season, (2) limiting the number of days dogs may be used to hunt hogs, (3) dividing management areas into “still” hunt and “dog-hunt” zones and alternating these from year to year, (4) having only special hog hunts with dogs permitted but not guns, (5) setting a limit on the number of hogs to be harvested and closing the season when that limit is reached, and (6) the complete exclusion of dogs for the purpose of hunting hogs. These regulations have centered mainly around the use of dogs to catch hogs and have generally been successful only in those areas which contain an abundance of escape cover (Belden and Frankenberger 1977). At present, hog dogs are allowed on 14 wildlife management areas and not permitted on 36 areas.

Based on data gathered in a study of wild hogs on the Fisheating Creek Refuge from July 1978 through June 1985, it would appear that harvesting a significant proportion (50-80%) of the younger age classes in late summer and early fall would be the best method to harvest a hog population on a sustained yield basis (Belden et al. 1985, Belden and Frankenberger 1990). This is the time of year when harvesting would have the least impact on suckling sows and when the subadult population (the harvestable surplus) is the highest in relation to the adult breeding population (without the presence of dependent pigs). Harvesting during this period would also reduce the population immediately prior to the acorn drop, thereby reducing the competition for available food, thus raising the nutritional plane for the remaining breeding stock. This should increase the number of pigs farrowed, their survival rate, and thus, the harvestable surplus for the next year. Present regulations harvest hog populations at the peak of the farrowing season and allow for the harvest of hogs down to a 15 inch shoulder height. The 15 inch shoulder height regulation only protects pigs < 6 weeks old, and this age group has a natural mortality rate between 75 and 90% (Belden et al. 1985). Therefore, the population is decimated unless there is enough escape cover for adequate breeding stock to survive the hunting season.

Wood and Barrett (1979) were of the opinion that the introduction or enhancement of wild hog populations was ecologically unsound. They cited as adverse effects the competition with native wildlife species, forest and agricultural crop depredations, and the potential of the wild hog as a reservoir for diseases communicable to man and his domestic animals.

The detrimental effects of wild hogs are multifaceted and result from their movements, habitat utilization, and food habits. Their rooting disrupts vegetative communities and successional patterns as well as alters nutrient cycling. Therefore, they can have both direct and indirect effects on some fauna either through predation or alteration of the forest floor habitat (Tate 1983). It is hypothesized that the wild hog is a fairly significant competitor for food with a number of other wildlife species such as deer, turkey, squirrels and even waterfowl (Thompson 1977). Evidence to support the hypothesis of competition is not available; however, if it does exist, most all agree that the effects would be worse during years of poor mast crops (Tate 1983).

There is indirect evidence that hogs may take injured wildlife including deer and perhaps newly dropped fawns. Wild hogs on coastal areas which serve as important nesting areas for marine turtles, especially the loggerhead, pose a serious threat to successful nesting of turtles which return to a traditional beach to nest (Thompson 1977).

Wild hogs in Florida are known to have 45 different parasitic and infectious diseases. These include 37 parasites (12 protozoans, 17 nematodes, 1 acanthocephalan, 1 sucking louse, 4 ticks and 2 mites), 7 bacteria, and 1 virus. Eight of these parasitic and infectious diseases can infect man. These include brucellosis, leptospirosis, salmonellosis, toxoplasmosis, balantidiasis, trichinosis, trichostrongylosis, and sarcoptic mange. In addition, all four species of ticks will feed on man if the opportunity is presented. These potential public health threats should be kept in mind when considering a wild hog stocking program (Forrester 1991).

In general, feral swine populations do not appear to be compatible with human activities in a rapidly developing region. The extensive rooting, wallowing, and nocturnal foraging activities are ecologically destructive to many natural habitats as well as most cover types created and maintained by man (Brown 1985). Wild hogs can also be a costly nuisance to agricultural landowners. Each year wild hogs uproot acres of improved pasture, sod fields, horticultural plots, and forage, vegetable, and fruit crops. Landowners then look for ways to economically and effectively control wild hog populations to suppress crop damage (Alshouse 1989).

Literature Cited

Alshouse, A. W. 1989. Why and how feral pigs get to market. Pages 42-43 in Proceedings of the Feral Pig Symposium, Orlando, FL. Livestock Conservation Institute, Madison, WI. 77pp.

Belden, R. C. and W. B. Frankenberger. 1977. Management of feral hogs in Florida–past, present, and future. Pages 5-10 in G. W. Wood, ed., Research & Management of Wild Hog Populations: Proceedings of a Symposium, Georgetown, S.C. 113pp.

_______ and _______. 1989. History and biology of feral swine. Pages 3-10 in Proc. Feral Pig Symp., April 27-29, Orlando, FL. Livestock Conservation Institute, Madison, WI. 77pp.

_______ and _______. 1990. Biology of a feral hog population in south central Florida. Proc. Annu. Conf. S.E. Assoc. Fish and Wildl. Agencies 44:in press.

_______, _______, and D. H. Austin. 1985. A simulated harvest study of feral hogs in Florida. Final Performance Report, Pittman-Robertson Project W-41-R, Study No. XIII-FEC, Florida Game and Fresh Water Fish Commission, Tallahassee. 83pp. illus.

Bowman, G. B. and F. Horne. 1982. Corbett hog regulations. Final Job Performance Report, Pittman-Robertson Project W-41-28, Florida Game and Fresh Water Fish Commission. 13pp.

Brown, L. N. 1985. Elimination of a small feral swine population in an urbanizing section of central Florida. Florida Sci. 48:120-123.

Degner, R. L. 1989. Economic importance of feral swine in Florida. Pages 39- 43 in Proceedings of the Feral Pig Symposium, Orlando, FL. Livestock Conservation Institute, Madison, WI. 77pp.

Forrester, D. J. 1991. Parasites and diseases of wild mammals in Florida. Univ. of Florida Press, Gainesville, FL. (in press)

Mayer, J. J. and I. L. Brisbin, Jr. 1991. Wild pigs in the United States: their history, comparative morphology, and current status. University of Georgia Press, Athens. 313pp.

Tate, J. (ed.). 1983. Techniques for controlling wild hogs in Great Smoky Mountains National Park: proceedings of a workshop, November 29-30, 1983. Research/Resources Management Rept. SER-72. USDI National Park Service, Gatlinburg, TN. 87pp.

Thompson, R. L. 1977. Feral hogs on National Wildlife Refuges. Pages 11-16 in G. W. Wood, ed., Research & Management of Wild Hog Populations: Proceedings of a Symposium, Georgetown, S.C. 113pp.

Wood, G. W. and R. H. Barrett. 1979. Status of wild pigs in the United States. Wildl. Soc. Bull. 7:237-246.

Figure 1. Distribution of feral hogs in Florida, 1988, based on 201 survey responses characterizing local hog population relative densities. Density categories are zero, low (hogs rarely seen, sign is scarce), medium (hogs not commonly seen, sign found intermittently), and high (hogs commonly seen, sign is abundant) density.