Park Declares Core Area Free Of Exotic Pigs

A significant milestone has been reached for the National Park Service at Pinnacles National Monument. Superintendent Eric Brunnemann has announced the successful removal of exotic pigs from inside the 14,500-acre core area of the monument’s 26,000 acres. The announcement culminates 23 years and $2.1 million of fence building, research, and removal of  an exotic animal that was introduced into California and has adversely impacted parts of the landscape ever since. 

The term exotic pig refers to wild boar, feral hogs, and their hybrids, all of which are varieties of Sus scrofa and not native to the Americas.  Feral hogs originate from domestic pigs that escaped from captivity. These hogs have existed in many parts of California since the late 1760s, when the Spanish began settling the region, but sightings in Pinnacles National Monument were relatively rare at the time the monument was established in 1908.  Wild boars, a European import, were brought to the eastern United States in 1910 and subsequently introduced to Monterey County (where Pinnacles is located) in 1925. Between 1955 and 1975, several hunters and landowners introduced wild boar in the immediate vicinity of the monument to improve sport hunting quality in the local populations. 



These wild boars bred with the already occurring feral hogs and the resulting hybrid pigs benefited from the wild boar’s natural ability to survive harsh conditions and tendency to range farther than feral hogs and aided in the spread of these animals. Exotic pig sightings increased from occasional to common and were sighted over an increasingly larger area as they moved into and stayed in the monument.  As their populations increased, so did the impacts to the environment.  Exotic pigs destroy native vegetation, compete with native wildlife for food, eat native wildlife, harbor diseases, increase soil erosion, promote exotic plant establishment, and degrade water quality.

Efforts to address the increasing impacts first began in 1984 with the launching of a project to construct a 30-mile-long pig exclusion fence that would protect the core of the monument. The fence path that was selected weaves throughout a rich, but rugged landscape of native environments, protecting the majority of the monument’s designated wilderness.  Once the fence was completed in October 2003 at a cost of $1.6 million, National Park Service biologists began the daunting task of developing a strategy for locating and removing every pig from within the confines of the fence.  Fieldwork for the removal of the pigs was led by the Institute for Wildlife Studies (IWS), a non-profit organization based in California. 

 “IWS came highly recommended to us and was brought into this project because of their experience in restoration programs, including removal of exotic species and reestablishment of rare species,” said Jim Petterson, the park’s supervisory wildlife biologist.

Only non-lead ammunition (Barnes X copper bullets) is used to dispatch the exotic pigs in order to prevent the potential for lead poisoning to California condors and other carrion eaters. 

Brunnemann acknowledged both the monument’s staff and IWS in accomplishing what no other unit of the National Park Service has accomplished in the lower 48 states – entirely removing non-native, exotic pigs from within a National Monument. 

“The dedication shown by all our staff — biologists, botanists, interpreters, rangers, and maintenance workers — all pulling together with our partners at IWS, has really paid off,” said Brunnemann. “We are already seeing real ecological benefits within our pig-free lands.  I’m seeing oak trees sprouting in places they haven’t been seen in decades, and hillsides that don’t look like someone went over them with a roto-tiller.”

A total of 197 exotic pigs were removed from inside the pig fence over the course of two-and-a-half years using a variety of techniques, such as trapping with sturdy metal chain-link box traps, tracking by using remotely-triggered cameras, dogs and radio-collared pigs, and  various ground hunting techniques. 

“We were able to complete the eradication through a successful partnership with NPS using a variety of very effective, well researched removal techniques,” said Blake McCann the wildlife biologist who supervised the project for IWS. “It took a concentrated year-round effort to achieve such a challenging goal.” 

A tremendous amount of work went into the removal process with over 12,000 person-hours devoted to the efforts.  One factor that was pivotal to the success of the project was the use of many different techniques on a year-round basis.  Efforts were broken up as follows:

• Trapping – 1,349.7 hours
• Dogs – 1,390.6 hours
• Ground hunting – 1,036.65 hours
• Radio-collared pig – 1,558.3 hours
• Admin – 2,978.85 hours
• Travel – 2,700.55 hours
• Monitoring – 1,161.8 hours