Previously one of the rarest fox species in the world, the island fox is only native to six small islands off the coast of California. These islands, collectively called the Channel Islands, each have their own specific subspecies of the fox. Descended from its bigger mainland variant the gray fox, these animals evolved independently after they arrived on the island 16,000 years ago. Their small size is speculated to be caused by the fewer resources on the island. By a hair, it is considered the smallest fox in North America.
Strangely enough, the island fox’s decline is linked to the extermination of an invasive feral pig population. When the National Park Service eradicated the hogs in the early 1990s, it also removed the primary food source of the golden eagle. Consequently, the eagles began preying on the foxes. The golden eagles were themselves migrants to the islands, drawn initially by the large feral pig population. Unlike the more adaptable feral pigs, foxes were vulnerable to the depredation. According to National Geographic, only a few dozen foxes existed across the islands by 1999. Now, biologists are reporting one of the fastest recoveries recorded in the history of the Endangered Species Act.
“They were listed as endangered in 2004, and they’re pretty much ready to come off that list at this point,” said NPS biologist Timothy Coonan.
The resurgence in the fox population was due to a multi-pronged effort by the NPS and Nature Conservancy. First, contract hunters were called in to remove non-native sheep, which had been eating and ripping up vegetation that the foxes used for cover. Then bald eagles were reintroduced to the islands. These larger birds historically kept golden eagles at bay and ate a diet of primarily fish, leaving the island fox unscathed. Unfortunately, the bald eagle had previously fled the islands due to high amounts of DDT in the ocean surrounding the region. Lastly, the migratory golden eagles were captured and released elsewhere.
As a result of these steps that now exists some 1,300 foxes on Santa Cruz Island and 500-600 on neighboring San Miguel and Santa Rosa islands.
“It’s actually a great stage to be here in the island recovery,” said Coonan. “I can sleep a little bit more at night because of everything that’s gone on.”
Image courtesy National Park Service