ANACAPA ISLAND, Calif. - Authorities say they've won the war against rats on a Southern California island.
A decade after a $3 million extermination effort, rare species are thriving on the rocky preserve a dozen miles offshore, National Park Service officials announced this week.
Ashy storm-petrels, a type of seabird, are nesting on the island for the first time ever recorded, and another seabird, the Cassin's auklet, has expanded its territories in the absence of rats as predators, according to a Park Service statement released Wednesday.
The number of Scripps's murrelet bird nests has quadrupled with a 50 percent increase of eggs hatched, the statement said.
"Nowhere are the threats of extinction higher than on islands, and nowhere do we have greater opportunities to save species at risk," said Gregg Howald, North America regional director for the group Island Conservation, a Park Service contractor.
"This successful project demonstrates the value of this critical conservation tool for other islands around the globe," he said in the statement.
The rat eradication is part of a continuing effort to restore the island's original species and eliminate nonnative species, such as iceplant, Channel Islands National Park Superintendent Russell Galipeau said.
Anacapa, one of a chain that comprises the Channel Islands National Park north of Los Angeles, has had non-native black rats for more than a century. Over the decades they devoured rare birds and their eggs, along with the deer mice, reptiles, insects and plants.
At one point, the rats were eating 70 percent of the eggs laid by Scripps's murrelets, a robin-sized bird that is listed by California as a threatened species, authorities said.
In 2001 and 2002, authorities struck back by dropping rat poison pellets by helicopter.
The goal was to exterminate the island rats.
"The last thing we needed was a project that got only 99.9 percent of all the island's rats," National Park Service biologist Kate Faulkner told the Los Angeles Times.
The program cost about $3 million, much of it funded by the American Trader Trustee Council, a conservation group.
The program was assisted by experts from the United States, Canada and New Zealand, but it also faced opposition from an animal rights group.
The Fund for Animals called the program an "ecological disaster" in a lawsuit that was later dismissed.