Albion Monitor /Features
 Alien Invaders: Hunter's trophy leaves swath of destruction

Rooting for Feral Pigs

by Simone Wilson

An industrious pig can tear up an acre in one night

Something is rototilling California, but it's not farmers discing the hillsides and fields, it's wild pigs in ever explosive numbers. An industrious pig can tear up an acre in one night and leave it looking as though a deranged army with shovels has passed by.

When hungry pigs plunge their tough snouts into the topsoil, foraging for acorns, bulbs and wild onions, the results are pretty much the same as rototilling, says Dr. Reginald Barrett, professor of wildlife at UC Berkeley's Department of Environmental Science. "Nutrients cycle faster and the ground is more fertile, but vegetation becomes less dense, too." On level soil, this rooting around leaves no more lasting damage than regular plowing does, says Barrett, "but with steeper terrain and thin, sandy soil, you can lose the entire soil layer in one big storm."

There aren't enough predators to put a dent in the boar population

Early Spanish ranchers brought the first pigs to California, figuring they could "transfer acorn fat to pig fat," says Barrett. They turned domestic pigs loose to fatten on acorns, then slaughtered the porkers. American ranchers continued the practice, and over time some pigs escaped and chowed down acorns without going back to get turned into ham. There have been feral pigs out there since mission times, mostly of the barnyard variety.

Then in 1923, a Carmel Valley rancher imported two dozen Eurasian wild boar from a private reserve in North Carolina, to be used as game animals. These were fierce, shaggy boars with a bad attitude -- just the kind of game hunters like to stalk. Some of the boars escaped and migrated into the coastal ridges, but it was hunters themselves who spread the hybridized hogs throughout the state.

"Hunters like the boar type," explains Barrett. "They'll kill a sow, and if the young have the striping typical of the wild strain, they'll toss the piglets in a gunny sack and dump them out elsewhere," to stock their own rural neighborhoods with game.

The feistier Eurasian boars met up with their escaped domestic cousins and bred a race of wild California pigs. Boar traits tend to predominate, because the boars, not surprisingly, are better adapted to the wild than escaped domestics. With litters of four to eight twice a year, the pigs proliferated and are now entrenched in most of California, except desert and snow country.

Predators don't hold the numbers in check. Coyotes nab piglets, but only cougars can take down an adult boar, and there aren't enough of them to put a dent in the boar population.

Drought and a resulting lack of acorns will cause pig numbers to plummet. "We could have lost two-thirds of the pig population in the last drought," says Barrett, "but two good acorn years and they bounce back. You could double the pig population every four years."

Like many successful introduced species, they're opportunistic feeders, pigging out on practically anything in the neighborhood. They forage for acorns and shoots (competing with deer) and are quick to scarf up newts, lizards and the eggs of ground-nesting birds like towhees and quail. When acorns and other preferred foods are in short supply, they raid orchards and fields.

"We try to fence them out," said a winery owner in the hills above Cazadero, who's tired of having pigs rototill his pinot noir. "If they get in, they end up in the freezer."

Farmers have been pressuring the state to allow the killing of pigs who threaten crops. Fish and Game, however, regards the pigs as game animals and sells permits that allow sport hunting of boar 365 days a year.

Unofficially, angry farmers probably shoot as many pigs as hunters do, and between them farmers and hunters provide a check on the numbers. "If there were a moratorium, in a couple of years it would be Pandemonium out there," says Barrett. "There'd be pigs in your backyard overturning garbage cans and rototilling the lawn."

Pigs are most often seen at twilight, but they're not so much nocturnal as partial to mild temperatures. In summer they forage at dusk when it's cool; when it's really cold they'll come out in the daytime.

Like most wildlife, wild pigs will generally run the other way rather than mess with people. But a pig can have a bad day. "That one in front of you could be the one in a thousand," says Barrett. "An older boar might just decide to go through you." The danger, he elaborates, is the tusks.

"They'll slap against your leg and slash the muscle off your leg." Barrett and a friend were out on a hillside when they encountered that one boar in a thousand. "A second later the pig ran off," says Barrett, "and my friend was standing there with his muscle in his hand."

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Albion Monitor March 10, 1996 (

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