5000 Wild pigs were killed to protect a national park in California

These days, it seems like small foxes rule the main islands in Channel Islands National Park. Sometimes they appear to be everywhere, scuttling along pathways, curled up in the grass, or grabbing mac & cheese from campers with impunity.

Although there are thousands of foxes in the eight-island chain, with over 2,500 of them on each of the two largest islands, Santa Rosa and Santa Cruz, they are still thought to be rather uncommon. The island foxes are a distinct species that have developed over many years from the gray foxes found on the mainland. Their only home is the chain of islands off the coast of Southern California. Furthermore, the fox has developed into a unique subspecies on each of the six islands where it is located.

However, the rare species was thought to be endangered until recently as a result of nonnative creatures being brought to the islands and driving them almost extinct. Their numbers on Santa Rosa and San Miguel Islands fell to just over a dozen foxes apiece at one point. When park officials realized that the island fox was in danger of going extinct in 2004, they decided to take dramatic measures. They hired contractors to slaughter almost 5,000 feral pigs in a methodical manner. The island fox was then categorized as endangered.

After the pigs were eradicated, the fox population quickly rebounded, and in 2016 it was the fastest-ever mammal to be delisted from the Endangered Species Act. The swift resurgence exemplifies the various ways in which the flora and fauna of Channel Islands National Park are recuperating after over a century of ranching and the invasion of nonnative species on the islands. It also highlights the rapid effects of introducing or removing a species on biologically isolated islands.

For a century, farm animals ruled the islands.

For many thousands of years, people have lived in the eight islands that make up the California Channel Islands, which are located west of Ventura and Santa Barbara counties.

The “Arlington Man,” whose remains are among the oldest ever recovered in North America, was found on Santa Rosa Island and is thought to have existed approximately 12,900 years ago. Native Chumash people also lived on the smaller, drier island of Anacapa Island. Historic Chumash town sites were also constructed in the northern Channel Islands of Santa Cruz, Santa Rosa, and San Miguel.

But the Chumash population on the islands decreased when Europeans arrived, bringing with them diseases and destroying their food supply. By the 1820s, the Chumash people on the island had moved to the mainland, where a large number were forced to work in missions.

Ranchers subsequently moved in. By 1844, Santa Rosa Island was full of horses, cattle, and sheep; by 1870, Santa Cruz Island was full with fifty thousand sheep. Up until 1999, ranching persisted in some capacity on the islands. By late 1998, the long-standing Santa Rosa Island ranching company Vail & Vickers had transferred all of its cattle off the island, and the following year, Santa Cruz Island’s sheep had been relocated as well.

In the 1850s, pigs were transported to Santa Cruz Island to be used as farm animals. A few pigs managed to get away, and as time went on, their numbers skyrocketed, creating a sizable wild population that ruled the island. Although the National Park Service did not acquire land on Santa Cruz Island until 1991, the island was included in the creation of Channel Islands National Park in 1980. About 75% of the island has been held by the nonprofit Nature Conservancy since 2001; the National Park Service is in charge of the other 25%.

At that point, the 96 square mile island was home to about 5,000 feral pigs, and park administrators faced a significant pig problem.

How pigs were “eradicated” in the thousands

On Santa Cruz Island, thousands of feral pigs were causing havoc in the beginning of the 2000s. Because of the pigs’ uprooting of the natural vegetation, there is erosion and an increase in exotic plants. These excavated and demolished significant Chumash cultural sites.

Additionally, they drew the golden eagle to the island, where it feasted on the pigs before swiftly catching up with the island foxes, who were unaccustomed to being attacked by air. In 2004, the island fox and thirteen plant species were listed as endangered, with park officials blaming the feral pig population as one of the main causes. According to Annie Little, supervising biologist at Channel Islands National Park, “the primary cause of decline of island foxes” was the feral pigs’ ability to attract golden eagles to the island.

Little stated, “The park management decided pretty early on that the pigs needed to be removed.”

“It was imperative that the pigs be removed in order to facilitate the recovery of rare and native plants as well as the island fox population,” the speaker went on.

According to Little, the National Park Service’s overarching plan to rehabilitate the islands included eliminating the feral pigs as well as other non-native species that were having “tremendous impacts.” There were other threats than pigs. The vegetation of the Channel Islands had also been severely damaged by grazing cattle and sheep. However, in 1999, Santa Cruz Island’s sheep population was eliminated, leaving pigs as the only “landscape-level impact.”

Following the 1993 “eradication” of feral pigs from Santa Rosa Island, the National Park Service and the Nature Conservancy announced in March 2005 the commencement of the Santa Cruz Island feral pig “eradication” effort. There were only approximately 1,000 pigs on Santa Rosa Island, though. The problem was five times that large on Santa Cruz.

On places like the Channel places, where we have unique species found nowhere else in the world, [invasive species] don’t necessarily have the choice to disperse to other sites, Little said. “Invasive species can have very detrimental impacts to biodiversity in general.” A wild pig can be found on the mainland, but they can even be unique to that island and only found there. Therefore, managers frequently have to make these difficult and difficult choices about the removal of nonnative animals.

Not everyone agreed with the decision. The eradication effort was sued in 2005 by a Santa Barbara businessman and two animal rights organizations, but the lawsuit was dropped out of court. According to Los Angeles Times reporting from the time, a large portion of the opposition centered on the choice to shoot the pigs, which opponents deemed barbaric. Instead, they pushed for a plan that would either trap and sterilize male pigs or kill the pigs by lethal injection.

Since the pigs might be disease carriers, they couldn’t simply be relocated to the mainland. Furthermore, although “sterilants and contraceptives are sometimes useful for animal control,” they are ineffective “for the eradication of pigs.” According to the National Park Service at the time, “controlling feral pigs would not lessen their destructive impacts to island resources.”

Rather, Prohunt, a professional hunting business from New Zealand, was brought in; the company’s area of expertise was taking down nonnative animals on delicate island ecosystems. The feral pig population on Santa Cruz Island was reduced to 5,036 by hunters who used traps, aerial hunting, and ground hunting in each of the island’s five sectors.

According to a 2008 Prohunt program assessment, “Prohunt’s strategic hunting approach was specifically designed to address and avoid the most common causes of failure in eradication projects.”It was essential to keep the pigs innocent of hunters during the endeavor. The development of an educated populace adept at eluding hunters would have posed the biggest threat to success. Prohunt claimed to have complied with the humane euthanasia requirements set forth by the American Veterinary Medical Association.

“As stewards, land managers, and environmentalists, we never take measures like these lightly. John Knapp, senior island biologist with the Nature Conservancy on Santa Cruz Island, stated, “Most people go into this field because they love nature, many of us are pet owners, and we have to take these kinds of dramatic actions to save a whole suite of biodiversity.”

However, the risks were great.

We are living through the sixth mass extinction. There is extinction taking place everywhere. Furthermore, Knapp said, “extinction was happening on the Channel Islands, right in our backyard.”

Alongside the pigs’ departure, forty-four golden eagles were captured and returned to the mainland. 61 bald eagles that had been restored to the island took their place. Before it was put in danger by people and pollutants like DDT in the 1950s, the official bird of the United States was seen flying over the islands. The bald eagle, in contrast to its golden brethren, usually catches fish rather than foxes.

On Santa Cruz Island, the last feral pig was killed by 2007. And the island has changed dramatically in the seventeen years that have passed.

A recuperating island

It was very different from what it is now when Knapp arrived on Santa Cruz Island, just at the end of the pig eradication effort. Pigs had trampled and degraded the ground severely, and while there were some trees and other vegetation on the slopes, there wasn’t much understory—a term used to describe the smaller trees and plants that grow beneath the larger trees—in the area.

According to Knapp, “there weren’t any layers of vegetation—there were just trees above or bare ground.” Acorns would be “gobbled up” by the feral pigs, stunting the growth of young oak trees on the island before they had a chance to set root.

However, according to Knapp, botanists were “completely dumbfounded by the level of complexity in the vegetation structure following the removal of the pigs” by 2015. The island has older oak trees that date back to the 1850s, before ranching became popular, but very few younger trees that had grown between the 1850s and 2007. He refers to the newer trees as the “Class of ’07,” since the trees took root following the removal of the pigs.

“There are locations now where you would never have seen carpets of seedlings surrounding large oaks,” Knapp remarked.

With the active removal of invasive plants by the Nature Conservancy, native vegetation gradually filled in the empty spots on hillsides. When the pigs controlled the island, one canyon known as the Laguna watershed was essentially simply puddles of water and exposed rocks. After two years, local cattails were discovered by botanists in the pools, retaining soil and creating the groundwork for the reemergence of further plants. Ten years later, the watershed was ringed with Humboldt lilies and exhibited twenty-foot-tall willow trees. In ten years, the entire area had transformed from exposed bedrock to riparian woodland.

Another indication of the island’s recovery occurred in November of last year when the U.S. Fish and Wildlife Service delisted two plants that were only found on the Channel Islands as fully recovered, ending their protection under the Endangered Species Act. Among them was the island bedstraw, which grows on the islands of Santa Cruz and San Miguel and is characterized as “a woody shrub plant with small flowers.” The plant had only a few hundred when it was first classified; today, there are more than fifteen thousand. Delisted was also the Santa Cruz Island dudleya, a flowering succulent exclusive to Santa Cruz Island.

Regaining their status as the little top predators on the islands, foxes have likewise made a full recovery. Before Knapp spotted a fox for the first time, he worked on the island for roughly four years, starting in 2010. Foxes are now commonplace thanks to a captive breeding program that was implemented at the same time as the pig eradication. According to Knapp, it’s challenging to travel the entire island without coming across at least six that are clearly visible from the road. According to Little, there is some belief that the fox population on Santa Cruz and Santa Rosa islands may be getting close to its carrying capacity, or upper limit.

The feral pig eradication effort was contentious at the time, despite being successful for endangered foxes and flora. Similar programs targeting nonnative species on other islands have also encountered controversy.

The Catalina Island Conservancy, which oversees most of Catalina Island, a nearby island that is part of the Channel Islands archipelago, abandoned its intention to shoot nonnative mule deer with helicopters in order to exterminate them earlier this year due to public protest.

According to Knapp, Santa Cruz Island’s comeback is an uncommon bright spot in an era of extinction brought on by climate change.

“I see the effects of large-scale fire, urbanization, and pollution when I’m on the other side of the channel on the mainland,” said Knapp. “When I visit the islands, the situation is different; I can observe how things are improving year after year and how they are recovering.”