Natural Area News - Pigs in the Park

San Antonio Natural Area Parks
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Pig in the Park
Peggy Spring
Education Coordinator

As you have been walking the trails of Friedrich Wilderness Park, have you noticed those areas that look like someone has been tilling the ground? No, we are not planning to plant potatoes and onions in the Natural Area. This is the work of feral hogs rooting through the park searching for food. Many of you have asked why we don't do something about this?

Feral (wild) hogs are the descendents of domestic hogs that have been abandoned or escaped from farms and ranches and Eurasian wild hogs, "Russian boars", that were released by ranchers and sportsmen for sport hunting. Due to extensive interbreeding between both pig groups, today's feral hogs range from relatively hairless to having a body covered with long, stiff, grizzled colored hairs. Hogs have four continuously growing tusks with the lower two being constantly sharpened by the opening and closing of the jaws. A mature hog may reach a shoulder height of 36 inches and weigh from 100 to over 400 pounds. They have relatively poor eyesight but have keen senses of hearing and smell.

Feral hogs are the most prolific large, wild mammal in North America. With adequate nutrition, a feral hog population can double in 4 months. Under favorable conditions, sows can produce two litters every 12 to 15 months, with an average of four to eight piglets per litter. The young are born a reddish color with black longitudinal stripes and as they mature the coat becomes highly variable. Solid black is the predominate color, but hogs also may be brown, red, white, spotted, belted (black or brownish red with a white band across the shoulders and forelimbs) or have rare blue or gray roan patterns. Their life expectancy is about four to five years, however, they may live up to eight years.

Feral hogs are omnivorous; they eat both plant and animal matter. They are very opportunistic feeders and much of their diet is based on seasonal availability. Foods include grasses, forbs, roots and tubers, browse, mast (acorns), fruits, bulbs and mushrooms as well as animal matter of invertebrates (insects, snails, earthworms, etc.), reptiles, amphibians, carrion (dead animals) and live mammals and birds if given the opportunity.

Measuring the environmental impact of feral hogs can be difficult. They compete with wildlife and livestock for habitat, harbor endemic and exotic diseases and transmit parasites to domestic livestock and humans. Livestock and crop damages run in the millions of dollars annually. Most important is the destruction of the habitat of native wildlife and the predation of wildlife. Feral hogs compete for food with many animals, including white-tailed deer, javelina, turkey, bobcat, and various small mammals. Extensive rooting of soils, forest litter and grasslands can cause serious erosion of riparian areas that leads to siltation, lower water quality, and sometimes fish kills. Rooting can also disrupt native plants and change the plant and animal community.

Feral hogs have been cited as the agent for eradication of many endemic species from numerous islands in various parts of the world, including Hawaii, California and Australia; it is reasonable to assume that similar damage will occur on mainlands.

In Friedrich Park, the impact of feral hogs from rooting and wallowing is obvious and extensive. (Their activity is also reported in nearby Crownridge Canyon Natural Area.) In the past, the park's population of feral hogs was controlled by trapping and removal. Current local ordinances have placed stringent restrictions on the methods of trapping and removal on city property such that we are no longer able to locate people to accomplish this work. We are aware of the damage they are doing and continue to pursue options to facilitate feral hog removal from the park. However, at present there seems to be no viable option.

If encountered, are feral hogs dangerous to humans? Feral hogs prefer to run and escape danger, but all wild animals have the potential to be dangerous, especially when wounded or cornered. In the City's Natural Areas they should be left alone!!

Sources of some information for this article:

The Feral Hog in Texas: R. Taylor, 1991, Texas Parks and Wildlife Department Federal Aid Report Series Number 28, Austin. PWD BK W7000-195 (9/03)

Feral Hogs in Texas: Mark E. Mapston, District Supervisor, Texas Cooperative Extension * Wildlife Services B-6149 (5-04).

Peggy Spring is the Park Naturalist in charge of education and volunteerism for San Antonio Natural Area Parks.

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Feral hogs are the most prolific large, wild mammal in North America. With adequate nutrition, a feral hog population can double in 4 months. Under favorable conditions, sows can produce two litters every 12 to 15 months, with an average of four to eight piglets per litter. The young are born a reddish color with black longitudinal stripes and as they mature the coat becomes highly variable. Solid black is the predominate color, but hogs also may be brown, red, white, spotted, belted (black or brownish red with a white band across the shoulders and forelimbs) or have rare blue or gray roan patterns. Their life expectancy is about four to five years, however, they may live up to eight years.

Feral hogs are omnivorous; they eat both plant and animal matter. They are very opportunistic feeders and much of their diet is based on seasonal availability. Foods include grasses, forbs, roots and tubers, browse, mast (acorns), fruits, bulbs and mushrooms as well as animal matter of invertebrates (insects, snails, earthworms, etc.), reptiles, amphibians, carrion (dead animals) and live mammals and birds if given the opportunity.

Measuring the environmental impact of feral hogs can be difficult. They compete with wildlife and livestock for habitat, harbor endemic and exotic diseases and transmit parasites to domestic livestock and humans. Livestock and crop damages run in the millions of dollars annually. Most important is the destruction of the habitat of native wildlife and the predation of wildlife. Feral hogs compete for food with many animals, including white-tailed deer, javelina, turkey, bobcat, and various small mammals. Extensive rooting of soils, forest litter and grasslands can cause serious erosion of riparian areas that leads to siltation, lower water quality, and sometimes fish kills. Rooting can also disrupt native plants and change the plant and animal community.