National Geographic Channel
for National Geographic News
The Channel Islands off the California coast are home to 145 species of plants and animals found nowhere else in the world. On Santa Cruz island, non-native feral pigs may be pushing the island's unique and endangered foxes to the brink of extinction. Now the island's managers are pushing back.
The nonprofit Nature Conservancy owns 76 percent of Santa Cruz Island. The National Park Service owns the rest. Together the agencies have crafted an island management plan that calls for an end to the pigs' tenure in paradise.
"The pigs have to go or ten species will likely go extinct, including the Santa Cruz island fox," said Julie Benson, a Nature Conservancy spokesperson. "This is a decision we had to make to preserve the biodiversity of the native species on the island."
A New Zealand-based company will begin hunting operations later this month. The company will aim to eradicate the island pig population over the next two to three years. Hunters will use a combination of traps, dogs, and helicopters to root the animals from the island's rugged terrainone-third of which is inaccessible by road.
"We've done a lot of research to decide the most humane method to correct this situation," said Yvonne Menard, a public information officer with Channel Islands National Park. "Feral pigs are so prolific. In less than a year they can bear two litters."
She added that control of populations, as opposed to completed eradication "is really not an option" because the numbers mushroom so quickly.
Golden vs. Bald Eagles
Feral pigs churn up soil and uproot native plant species, denuding landscapes and promoting weed growth. The pigs also attract golden eagles, which prey on the charismatic island fox (Urocyon littoralis), a species found nowhere else in the world.
"Pigs exist all over the world, and feral pigs are the same species as domestic pigs (Sus scrofa)," Benson, the Nature Conservancy spokesperson, explained. "But it takes thousands of years for a subspecies to evolve. The island fox has been out there for 18,000 years."
The fox shows its evolutionary age by exhibiting dwarfism. The trait is found in isolated island mammal populations. Large island mammals become smaller through the generations as they adapt, through genetic selection, to the limited resources of their environment. (The reverse is true for small island mammals.)
The Santa Cruz island fox weighs 5 pounds (2.25 kilograms), one-third the mass of its evolutionary ancestor, the mainland gray fox.
Despite their long tenure, island fox populations have crashed to dangerous levels in recent years. They landed on the U.S. endangered species list in March 2004. Many scientists pin the problem squarely on feral hogs.
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