The study was conducted by University of California at Davis conservation biologist Rosemary Woodroffe, Gary Roemer of New Mexico State University and Franck Courchamp of Universite Paris-Sud.

They said that in less than a decade, the native fox population on six Channel Islands, about 20 miles off the Southern California coast, fell by 90 percent due to golden eagle predation and disease.

Efforts to re-establish the cat-sized fox has succeeded only on Santa Catalina Island, where golden eagles were held in check by territorial bald eagles, which prey mainly on fish.

But subspecies of foxes on two other islands are now extinct in the wild because officials were unable to capture and relocate a handful of golden eagles that prey freely on the unwary fox, the article said.

Scientists postulated that the threat to the foxes would only increase if conservationists proceeded with plans to remove non-native pigs from the islands in the coming months.

"Alternative prey might be expected to lessen the eagle's impact on the fox, but our previous work suggests that foxes and piglets were the eagles' principle prey," the article said. "Unexpectedly, pig control leads to decline or extinction of the fox population if eagle control is insufficient."

Ann Muscat, president of the Catalina Island Conservancy, celebrated a milestone this week in her organization's efforts to bring back the fox after its numbers dropped from 1,200 to 100 due after a canine distemper outbreak.