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CURWOOD: Of the hundreds of exotic animal species deliberately or inadvertently introduced to North America, the wild pig is among the most controversial. These animals can weigh upwards of 300 pounds. Some are descended from barnyard escapees, others from Eurasian wild boars that were introduced for hunting in the 1920's.
Many are a mix and just about all of them are hardy, tough, omnivorous, and adaptable. For years, these swine have been increasing their range. And they're now found in significant numbers in at least 17 states. Some hunters prize them as game. Others see them as an ecological nightmare. By far, the largest population of feral pigs is in California, as Clay Scott reports.
SCOTT: Portola Valley, California, in the oak-covered hills above Stanford University, is a community that prides itself on being close to nature. A town ordinance prohibits the building of fences between properties in order to ensure habitat corridors for wildlife. And people here enjoy the sight of daintily-stepping blacktail deer, California quail, and the occasional gray fox or bobcat.
But, one morning not too long ago, residents awoke to find that nature had come a little too close for comfort.
HOWARD: We started receiving phones calls from, first, property owners that their landscaping had been destroyed.
SCOTT: Angela Howard is Portola Valley's town administrator. The culprits, she says, turned out to be a group of wild pigs literally eating their way through town.
HOWARD: The pigs migrated down behind the creek, and ended up eating up our soccer field. And I was really surprised at how much damage they can do in a relative short amount of time. It's like someone had taken some sort of machinery and just dug up the whole field. It was just amazing.
(Photo: Rick Sweitzer)
SCOTT: Overnight, the pigs also devoured lawns and flowerbeds, and dug up sprinkler systems. Not only did they cause physical damage, but many residents said they feared for their safety, and that of their pets. Even the animal-friendly town council of Portola Valley knew it had to take drastic steps.
HOWARD: When we had the discussion at the council level, it was pretty apparent that there was no way to relocate them. Nobody wanted them. We couldn't keep them out by just fencing, although we talked about that. So, the decision was made to try to harvest them.
SCOTT: The man they hired to remove the pigs, Dick Seever, is remarkably good at his job. Probably no trapper on the west coast is in higher demand.
SEEVER: We have probably killed seven or eight thousand pigs since 1994. And that all was in 50 miles of San Francisco. There's a lot of pigs in the area, or used to be.
SCOTT: Seever has been hunting and trapping California's wild pigs for over 20 years. On a recent morning before dawn, he took me to a wooded ridge overlooking Silicon Valley and San Francisco Bay beyond. Seever has several current trapping contracts in this area. Among them, a county park and a film executive upset that the pigs have ruined his bonsai garden.
Here, where multi-million dollar houses lie hidden among live oak and sequoia, he set out half a dozen traps. He proudly shows me one of the homemade steel pens, 12x4x4, bated with a concoction of fermented corn mash so foul it makes you gag. To wild pigs, Seever says, it's as enticing as the aroma of fresh-baked bread.
SEEVER: The trap is set just like that. The pipe is holding it up. And the pigs come through this corn. And they eat all this corn. And once they get all the way to the back of the trap, there's a pulley and a string here. They get back to the trap. They hit this string. [SOUND OF DOOR SHUTTING] And at this time, they go kind of crazy for a few minutes. All the noise. They're trying to get out. And then they calm down, and they eat all the feed. A lot of times, I come to the trap in the morning and they're all in there sleeping.
SCOTT: Dick Seever has been hired by state, county, and municipal agencies, golf courses, airports, private residents, all of them desperate to get rid of wild pigs. For the most part, he works on the fringes of populated areas, checking his traps well before dawn.
Even people who are paying him to eliminate the animals, he says, prefer not to know exactly how he goes about his business. As for the general public, experience has taught him to keep a low profile.
SEEVER: I've had people cut my tires on my trailer. I've had people steal my traps. I've had all kinds of experience with people. But the animal rights people think that these pigs should live until they die. And, hey, if they were tearing up your back yard, it's a different story. When it's somebody else's back yard, I guess it don't matter.
SCOTT: Seever shoots the pigs in the trap using a .22 rifle. He used to donate the meat to soup kitchens and charities until health authorities cracked down, since the meat hadn't gone through federal inspection. Now he delivers the carcasses to a tallow factory where they end up as soap, bone meal, and makeup.
His services are not only in demand in the suburbs, he was recently hired to trap pigs in Henry Coe State Park, 135 square miles of virtual wilderness southeast of San Jose. In three months last spring and summer, Seever killed 750 pigs. But park superintendent Kay Robinson says that number is only a drop in the bucket. She worries the pigs will do lasting environmental damage.
ROBINSON: We thought 750 would be a tremendous step in the right direction. But, every patrol that we're out there in the park, we see more and more and more. So, the effect that they create on the landscape is going to affect California landscape many years down the line, primarily for the vegetation.
[SOUND OF BIRDS]
SCOTT: With its deep canyons thick with chemise and manzanita, and woodlands of blue oak and gray pine, Coe Park is home to hundreds of species of plants and animals, from mountain lions and tule elk, to rare plants and insects. It wasn't that long ago that wild pigs were unknown here. Now, the park has mainland California's highest density of the animals. And their impact can be seen throughout the ecosystem.
SWEITZER: On an annual basis, pigs are rooting up anywhere from 40 to 60 percent of the oak grassland, or the grasslands in this park.
SCOTT: Rick Sweitzer, a biologist from the University of North Dakota, has spent years studying California's wild pigs. We hiked through an open oak savannah. And the pigs' rooting is visible everywhere. Entire hillsides are scarred, hundreds of acres dug up as if roto-tilled. The pigs dig for grubs, worms, bulbs, roots and, above all, acorns. Their passion for acorns affects the ecosystem in many ways. They compete with native wildlife, and have been linked to the decline of species such as blacktail deer and western gray squirrels, which also depend on acorns.
Their rooting disturbs the habitat of ground squirrels, mice and other rodents that provide foot for predators. The torn-up ground also causes erosion, and speeds up the spread of exotic weeds such as star thistle which, in turn, choke out native grasses. And, biologists here are particularly worried about the pigs' effect on the health of California's blue oaks.
(Photo: Rick Sweitzer)
SWEITZER: It's a high level of disturbance that's been repeated year after year, to the extent that the seedlings that might be growing underneath these blue oak trees are going to be uprooted. And we're going to see reduced oak regeneration and changes in plant communities, as a result of this repeated disturbance.
SCOTT: For the last three years, Sweitzer has been monitoring pig damage by means of exclosure plots, fenced in such a way that pigs are excluded, but deer and other animals can enter. Next to each exclosure is an unfenced control plot, and the contrast is striking. Within the fenced area, oak seedlings and native grasses grow. Outside, not a seedling is in sight. The soil is torn up. And signs of pig activity are everywhere; their pointed tracks, their droppings, and the dried gray mud they have rubbed on the trunks of oak trees. On this day, with so much evidence around, we knew it was only a matter of time before the animals themselves appeared.
SWEITZER (whispering): There's a group of about 25 pigs on the hillside in the distance. And these guys are moving pretty fast. It looks like they're heading somewhere with a purpose in mind.
SCOTT: The animals are about 400 yards away, black shapes conspicuous against the rich green winter grass. We decide to try and get closer. We duck out of sight below a low rise, and job for about 300 yards until we approach the meadow where we saw the pigs.
SCOTT (Whispering to Sweitzer): Hard to believe 20 animals could disappear that quickly.
SWEITZER: I'll bet they went over that ridge right down there in front of us. Want to walk down there?
[SOUNDS OF WALKING]
(Photo: Rick Sweitzer)
SCOTT: Suddenly, we come upon them less than a hundred yards away, sow and piglets feeding under a large valley oak. The wind is in our favor, so we sneak closer. We're only a few yards away when two males emerge from the brush.
SWEITZER: That's a big boar right there, the one with the foam coming out of his mouth.
SCOTT: How big is that one boar, would you say?
SWEITZER: I can see his scrotum. He's a big male. He's probably close to 320, 330 pounds. See, he's challenging that other boar right there.
[SOUNDS OF PIGS]
SCOTT: Pigs have notoriously weak eyesight, but they can pick up movement. We don't want to startle a cranky boar the size of a sumo wrestler with razor-sharp tusks. We finally decide 15 yards is not a prudent distance, and sneak away. Having observed the animals at close range, it's obvious why no predator will tackle them once they're full-grown. Even though mountain lions and coyotes do kill many piglets, Sweitzer says, the animals reproduce so quickly that neither predation nor hunting seems to make a long-term dent in their numbers.
SWEITZER: If it's a good year, within a year they are going to be able to recover the numbers that they were before the control efforts started. And a good year would be a good, wet, year with a lot of acorns. And the numbers will just skyrocket. To really show a significant reduction in the amount of rooting that we're seeing on an annual basis, you need to remove, at this point, 50 to 60 percent of the animals from the population.
SCOTT: That would require an intensive, costly, state-wide trapping effort, something that seems unlikely to happen. In the meantime, say biologists, pigs will thrive where ever there is suitable habitat. And California, with its millions of acres of oak woodlands, could not be more ideal for the animals. It's far too soon to predict the pigs' long-term impact on the environment. But, like the golden wild oats that cover the foothills in this state, another aggressive import from overseas--the wild pig--seems destined to be a permanent feature of the California landscape. For Living on Earth, I'm Clay Scott in Santa Clara County, California.
[MUSIC: Kronos Quartet "Saade" Pieces of Africa Elektra (1992)]
CURWOOD: Just a few months ago, I was in the back of a Land Rover, driving across an African savannah under a crystal clear sky. As the sun was setting, we came across a solitary leopard trying to pull an antelope up into a tree. As we watched, we realized the leopard had a cub with her.
Now, our trackers had told us that these animals on the game preserves regard folks in Land Rovers as part of some relatively huge, benign animal. And, usually, they'll let you get close. But, this mom, with her baby and her antelope dinner, was in no mood for strangers. She walked right up to our truck and glared at us. A chill ran down my spine as I realized that we were just one swat away from her. And that would happen long before our tracker could grab the rifle on the dashboard of the Land Rover. I'll never forget the look in the leopard's eyes. She said, "This is my meat, my kid. I'm the boss."
Now, Living on Earth wants to give you a chance at your own African safari. Thanks to Heritage Africa, we're giving away a 15-day trip for two on the ultimate African safari, with visits to several of Africa's most spectacular game preserve, such as Krueger, where I saw this leopard, and the Serengeti.
For more details about how to win this 15-day African safari, just go to our website, loe.org. That's www.loe.org for the trip of a lifetime.
ANNOUNCER: Funding for Living on Earth comes from the World Media Foundation. Major contributors include The Ford Foundation, for reporting on U.S. environment and development issues, and The William and Flora Hewlett Foundation, for coverage of Western issues. Support also comes from NPR member stations and the Overbrook Foundation, working with the Natural Resources Defense Council to safeguard the earth, and the natural systems on which all life depends, and Bob Williams and Meg Caldwell, honoring NPR's coverage of environmental and natural resource issues, and in support of the NPR President's Council.