Wildlife of Henry W. Coe State Park
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Wild Pig
Sus scrofa

Young pig and photographer's shadow, illustrating how unaware
the pigs are of people.  Once it sensed me, it took off running.

Along County Line Road just west of Kaiser-Aetna Road.

November 22, 1991.

Photo copyright Ó Lee Dittmann.

Juvenile pigs (piglets) are brown and striped---and exceptionally cute, like other young mammals.

Near Cross Canyon Trail, Kelly Cabin Canyon.

April 2002

Photo copyright Ó Don Savant, used with permission.

Some biologists prefer to use the term "feral pig,"  but strictly speaking, a feral animal is one escaped from domestication, and their descendents.  The pigs at Coe are thought to have genes from the Russian wild boar as well as those of domestic pigs, so I don't believe the term "feral" is applicable to this population.  These pigs are not native to North America (the native peccaries of the southwest deserts are in a different family of mammals and are not found in this region).

Wild pigs are quite common at Coe, and are sometimes mistaken for bears by people who hear their strange grunts and growls or who see them from the backside only.  (There are no bears at Coe, the California Grizzly is long extinct.)

The "Pig Problem"

Visitors frequently comment on the "pig problem" at Coe Park.  They see the large areas of soil overturned by pigs searching for grubs, worms, acorns and other edibles and wonder what the park is going to do about it.  They are also concerned about pigs attacking people.  The implied assumptions are that 1) Pigs are causing untold destruction and have no place in the area ecology, 2) Their numbers will increase until the park is devastated, 3) They are dangerous, and 4) There are practical ways to "take care" of the problem.

As a former volunteer and employee who worked at the park for over nine years and who has observed hundreds, if not thousands, of wild pigs and the effects of their rooting, I've developed some ideas contrary to the aforementioned assumptions.  Here are my observations on the problem and what to do about it.  The opinions expressed do not necessarily coincide with those of California State Parks:

First, the park's general plan (approved in 1985, I think) addresses the pig situation in one line. It says they will be eradicated. It doesn't say how or when.

Second, how real a problem is it?  Superficially, when you know that the pigs aren't native and you see them in abundance plowing up large areas, then surely they must be causing great environmental damage?

But it isn't so simple, and the reason is grizzly bears. The California Grizzly, now extinct (and seen at the park only on the state flag and on park employees' uniforms and other emblems), had an influence on the land strikingly similar to that of the wild pigs. They ate about the same things: bulbs, acorns, carrion, worms, grubs, just about anything edible. And much of what they ate they obtained in a similar fashion, by plowing up the earth. Pigs root with their snouts, but grizzlies did this with their long claws. There is a description of a Mount Diablo hillside in the 1800s in the classic book The California Grizzly which you would swear describes the churned-up soil left by pigs.  But that hillside was clawed up by grizzlies.

When such a plowing has existed on the land for tens of thousands of years before the extinction of grizzlies, you can bet that there are native plants which benefit from this, and indeed, California poppies seem to do well after pig plowing.  I've also seen pigs plow through fields of the native perennial wild pansies (Viola peduculata), and the following year the pansies were as abundant as ever.  The one problem with pigs and plants is that now there are many alien species of plants in the park which also do well with plowing, and many of these spread faster on plowed land than native species.  But I don't know of any rare species of plants which are directly threatened by pigs---in marked contrast to the situation in Hawai'i.

Aren't the pigs competing with native wildlife?  Yes, pigs do eat acorns that deer need to fatten up for the winter---as my friend Ranger Barry Breckling has pointed out.  But the California Grizzly also gorged itself on acorns, and if it came across a young fawn hidden away in the spring, would probably have eaten it, too.  It is highly debatable that the deer population is any lower now than three hundred years ago, since the native people, the Ohlone and Yokuts, would also have competed with the deer (for acorns) as well as hunting the deer for food themselves.  Since no hunting by humans is now allowed (though there has been poaching) and since the grizzlies are extinct, it is quite possible that the pigs have brought back the level of competition the deer have been accustomed to most of the past several thousand years.


People have heard tales about the aggressive nature of wild pigs, fueled, it seems, by the stories of hunters treed by wounded boar.  What they don't seem to consider is that wounded animals act differently than healthy animals, and that hunters may have an incentive to embellish to make themselves look manlier vis a vis this wild beast.  When I first saw a group of pigs coming my way up on Blue Ridge, I looked for a tree I could climb---but was surprised, and pleased, that once they caught scent of me, they ran off in the other direction.  Since then, I've realized that there is very little danger to us from any pig that has a way out. The reason they sometimes seem to be coming at you is that they have very poor eyesight, and haven't even sensed you. I've learned that a loud WHOOP and jumping up and down waving my arms like an idiot is an effective, exhilarating, and satisfying way of getting them to run in the other direction.

Mama pigs

Some folks will say that, while the above may well be true, stay away from a mama pig and her piglets. She'll be aggressive in protecting her own, they say.  This is certainly true with bears, but in my experience at Coe, is mostly nonsense with pigs.  Having learned their nature, I've gone up to groups of pigs, maybe two dozen or so with many piglets and several sows.  Once they detected me, the whole group scattered in all directions, mothers paying no attention to piglets.  This makes biological sense, for generally animals with large litters (and pigs have something like 8 or more piglets per litter, and often two litters per year), have higher mortality.  In a biological sense, they "expect" to lose a lot of offspring and it seems their survival  strategy is "Everyone run and scatter and if we lose of few of the young, there's plenty more where those came from!"  This is in contrast to a bear's two cubs per year which will indeed be defended quite aggressively.

All in all, the pigs are much easier to live with in a recreational park than the original grizzly bear inhabitants, who apparently ran from nothing except maybe other larger, individual bears.

Back around 1994, there was one or more pigs who were raiding backpacker's food, and which would not shoo away. These pigs were believed to have been the subjects of a study. The park authorized some researchers in the Mahoney Meadows area to live trap and release pigs in order to get information on their home ranges. Trouble was, the repeated trapping and releasing accustomed these pigs to humans, and made them associate us with food. "If there is a human scent, they are going to feed you and not hurt you. Don't bother running from them!"

That group of pigs the park had trapped and taken away for slaughter.

Why can't they all be trapped and removed?

If they can do that for one group of pigs, why can't the park do that to all of them? One reason is that law or policy now (or at least a few years ago) required that wild pigs trapped and slaughtered in removal programs be dressed, cooked, and given to food bank charities. Apparently, there are so many pigs being removed from various lands, that there is more wild pork than anyone can handle.

Second, even if the park managed to trap and remove all of the pigs on park lands on any given year (a daunting task), within weeks if not days, you would have pigs wandering in from adjacent private lands. You would have to have range-wide eradication to have effective long-term control. And while a lot of ranchers would like to see that happen, most hunters wouldn't.  Even if pigs did not exist outside the park, you would still have to trap a large proportion (if I remember correctly, a biologist's estimate was 2/3rds) to have a significant dent in their population during the course of a couple of years. They breed so fast that their populations would soon be back up to where they were.

More and more and more?

Which brings us to another aspect of their reproduction. With such a rapid breeding rate, won't there just be more and more of them every year?  No, it turns out. One controlling factor on pig populations seems to be the availability of water, probably also of food.  In drought years, the pig population has been way down. With the more recent wet or average years, the pig population climbed.  But given their high rate of breeding, they are obviously suffering from some type of mortality, whether predation, parasites, or disease (possibly exacerbated by a poor diet from competition with other animals or a poor acorn crop.)

Pig predators

But, other than humans, aren't pigs free of predators? I've read someone claim that since they are non-native, they have no "natural" predators.  Not true, unless you consider mountain lions and coyotes unnatural. Mountain lion expert Rick Hopkins reported at least one case of finding a pig carcass that had been eaten by a lion. More remarkably, volunteer Ruby Domino observed a coyote dragging a medium-sized pig into Fish and Game Pond (just south of Coit Lake), in an apparent attempt to drown it.  While predatory mammals have a culture (culture being broadly defined as any behavior of an animal which is passed on down the generations by learning from others of its kind, usually its parents) which tends to keep them eating what they are accustomed to, that culture can change over time. (This may well be why mountain lions in parks usually shy away from people, even though they have rarely personally experienced dangerous hostility from humans.  Why else do they not frequently attack and eat wimpy human beings left and right?  Doing so is not in their heritage, and they may have a cultural "memory" of humans as dangerous enemies.  There has never yet been a mountain lion attack on a human at Coe Park.)

Yet during times of a poor regular food supply, an intelligent predatory mammal like a lion, coyote, or bobcat may venture to try out something different. And observing how undefended a round little piglet is, it is only a matter of time before they become a regular part of the menu. I predict that sooner or later, the pigs, even with no management, will reach an equilibrium at a lower population than now exists. It may take decades, even centuries, but an unutilized food source will not be left untapped for long.

Open the park to hunters?

Supposing that pigs are destructive enough at their current level of population (which I suspect is indeed more massive than that which was enjoyed by the grizzlies), couldn't the park be opened to private hunters for some season so they could shoot the pigs?  No, not without a major change in law, which prohibits hunting in state parks. But even if the law were changed, what good would it really do?  The park would lose other forms of recreationalists during this hypothetical hunting season (and even more if you allowed it year-round; how many of us want to hike and bike among hunters?).  And you would probably lose visitors even longer, for once the park obtained a reputation for being a hunting park, a significant portion of the public would stay away, based on misinformation or misunderstanding.

Most importantly, the private hunters would probably not be able to make a long-term dent in the population, hunting in the park would gain a political constituency and would then be hard to stop, and what do you do with all the carcasses?  Hunters could only take so many---big pigs are heavy---and do you let them drive all over the park, on dirt roads now closed to the public?  Or do you leave the hundreds of carcasses which would need to result for hunting to make a dent in the population just rot for the vultures?  I like vultures, nothing against feeding them, but I doubt many users would like to find pig carcasses around every half mile of trail. (Also, lead shot is a potentially lethal hazard to California condors, should condors make their way up to Coe from more southerly re-establishing populations.  Grand Canyon region condors have been poisoned by lead they ingest while feeding on bullet-killed carcasses.)

The ethics of killing pigs

Not to be ignored are the ethics of killing pigs.  Though I am a vegetarian by reason of wishing to cause as little pain to other animals as possible, when the survival of an entire species of wild plant or animal is threatened by an imported animal---as is the case with pigs in Hawai'i, then killing them---as quickly as practical---may be the only solution.   In Hawai'i, the sooner they are removed the better.  At Coe Park, speed is less critical for they do not have quite so radical an impact.   Ideally, it would be best if you could sterilize them all (or at least 100% of one sex) and let them die out of old age and predation, but achieving that 100% would probably be impossible.  If thousands of landowners had a desire to adopt pigs as pets, it would also be good to trap and remove them for that purpose;  but the desire for pet pigs is almost non-existent.

Therefore I think it is ethically justifiable to live trap, remove, and kill pigs as painlessly as practical when their populations reach excessive levels.  The alternative for the pigs themselves is death by starvation or disease.


This is not a simple problem, nor are there simple solutions.  The pig problem is really two problems:  1) That there are probably too many pigs at present for optimum health of many of the native plants and animals (especially since there are aggressive non-native plants present which colonize the areas disturbed by pigs faster than most natives).  2) Education of the public that pigs are not all that dangerous (certainly far less than grizzly bears), that they are not as harmful to the environment as one may first suppose, and that constraints of the real world (rapid breeding of the pigs, desire by hunters to not eliminate them entirely from California, image of the park as an area protected from hunting, and funding limits, for example) prevent any "easy" solutions.

My completely unofficial but informed opinion is that the park should continue trapping problem individuals or groups when it can do so, but that the biggest effort should go into research to mitigate the effects of pigs on the native landscape and into education of the public about the grizzly/pig similarity.  We can learn to live with pigs, for we may have to.  Sooner or later the pigs will become a regular part of the diet of native predators and will level out at a lower population.

--Lee Dittmann

Notes:  One reader from Tehama County believes I should stress the danger of encounters with pigs.  He writes:
"I can speak firsthand on the potential dangers of a close encounter with a wild boar. One evening about a year ago my wife and I were walking our two dogs about a mile from my home when a large black boar suddenly flushed from a manzanita thicket and attacked my dogs. In my attempt to break up the fracas I was charged by the boar and had to scale an oak tree to escape. My female 100 lb. American Bulldog was KILLED by the boar. Her chest was badly lacerated by a tusk. THEY ARE POTENTIALLY DANGEROUS!!!
I would advise people to be very cautious if they come in close contact with wild pigs."

In response, the above essay is written based on my experience in Coe Park.  Dogs are not allowed on backcountry trails at Coe, and in the few areas they are allowed, they must be on a leash.  The reader's experience underlines the importance of keeping dogs on leashes in areas where they are allowed, not only for the safety and well-being of wildlife, but for the dog's own safety.

Revised 31 March 2005

Wildlife of Henry Coe State Park
Henry W. Coe State Park, California
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