Three subspecies of island fox that nearly became extinct in California two decades ago have recovered so fully that federal officials today announced their removal from protection under the Endangered Species Act, providing a powerful success story for legislation many detractors call flawed.

The foxes had fallen from about 4,000 on three of the Channel Islands—Santa Cruz, Santa Rosa and San Miguel—in 1994 to fewer than 100 by 1999, due in part to a proliferation of nonnative feral pigs that attracted legions of predatory golden eagles, say federal and conservation biologists who assisted in their recovery.

But after the cat-sized island foxes were listed as endangered in 2004, the National Park Service, U.S. Fish and Wildlife Service and Nature Conservancy, among others, ramped up an eradication of the pigs and capture and removal of the eagles. That allowed the foxes to rebound to their old levels, prompting the Fish and Wildlife Service to issue its fastest delisting of a mammal—which can take 25 years or more to recover—since the Endangered Species Act was passed in 1973.

“At the core of this was a bunch of people coming together and deciding they wouldn’t let a species go extinct on their watch,” said Scott Morrison, California science director for the Arlington, Va.-based Nature Conservancy, which owns three-quarters of Santa Cruz Island off the coast of Ventura, Calif. The rest of the island, along with Santa Rosa and San Miguel, are part of Channel Islands National Park.

The island fox’s success comes as the Endangered Species Act in recent years has come under assault from many Republican lawmakers on Capitol Hill, who say so few species ever leave protected status that it needs to be overhauled.