Hundreds of thousands of feral pigs are wreaking havoc on the state of California. The animals are destroying native plants, spreading disease and threatening people.
Feral pigs have been identified in 56 of California's 58 counties and their existence is a major problem for farmers, homeowners, biologists, and government land managers. The pigs cause enormous ecological damage using their snouts and hooves to unearth dirt-dwelling insect larvae, eat acorns, invertebrates, eggs, small animals and plants. The feces of these large animals also poses a major threat as it can carry over 30 infectious diseases, including 20 that can be transmitted to humans, like leptospirosis, toxoplasmosis and tularemia.
A 2006 E.coli outbreak in spinach grown in Salina Valley, California was caused by swine, and water regulator and engineers worry that pigs could contaminate reservoirs and rivers as well.
Environmental agencies have dubbed feral pigs as the "most destructive," invasive species in the country. Over 6 million feral pigs are estimated to exist nationwide across 42 states, including Hawaii. The U.S. Department of Agriculture says they cause between $1.5 ad $2.5 billion dollars in damage to agriculture and property annually.
Adults pigs can grow as large as 500 pounds, 150 on the small side. Because of their size and their tendency to live in packs of 15-20 they have few natural predators, which means their numbers are growing exponentially.
Where They Came From.
The feral pigs causing such problems for the U.S. are not native to the continent, but are a byproduct of pigs brought by Spanish missionaries in the 1700s and wild boars brought to Monterey, California in the 1920s. This combination created what some biologist call "super pigs," incredibly smart, with an adaptable diet that allows them to occupy a number of environments, and the ability to rapidly reproduce. Females can become pregnant at 4 months old, and can deliver 4 litters per year of up 18 piglets per litter.
What Can Be Done.
Legislation has been introduced that will relax regulations for sport hunting of wild pigs. Some experts say there is evidence that this won't work, and that hunting actually promotes the spread of swine. There are also very few places where the public is allowed to hunt in the state of California.
In Santa Clara County, land managers have seen some success with reducing food sources by introducing worm-like creatures called predatory nematodes into the soil, which reduces the grubs that pigs like to eat. Unfortunately, this isn't feasible on a large scale since nematodes should not be allowed in residential areas.
In 2007 on Santa Cruz Island, National Park Service employees eradicated feral pigs by killing 5,036 of them.
A 33-mile fence was built around Pinnacles National Park in Northern California. It took almost two decades to construct, but after the fence was complete, park employees spent another two years trapping and hunting all of the pigs that lived inside it.
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