Surviving at the top of the food chain is just as tough as struggling at the bottom; there’s always something that wants to knock you down. That was the case for the pint-size island fox on the majestic Channel Islands.
About the size of a small house cat, the rust and cinnamon-colored canine was nearly picked clean by golden eagles on San Miguel, Santa Cruz and Santa Rosa islands by 1999. It’s been listed on the U.S. Fish and Wildlife Service’s Endangered Species List since 2004.
Originally lured to the volcanic chain by an extensive feral pig population on Santa Cruz, golden eagles soon realized that island foxes were an easier catch, not only on the largest of the Channel Islands, but also on neighboring San Miguel and Santa Rosa.
Fast forward to November 2009, and the fragile island ecosystem is reaching some ecological stability. The 5,000 feral pigs were officially eradicated in the spring of 2008 and 43 golden eagles were trapped, attached with GPS units and relocated back to northeastern California. None of those raptors have returned. Bald eagles were returned to the islands between 2002 and 2006 to re-establish historic nesting habitat, while keeping potential golden eagles at bay. The results have been astounding for island fox populations across the unique Channel Islands National Park archipelago.
“We’ve removed the predation pressure on the foxes,” said Tim Coonan, terrestrial biologist for Channel Islands National Park. “Now the foxes know what to do.”
What they’ve done is proliferate since the last captive island fox was released on Santa Rosa in November 2008. Historically, Santa Cruz and Santa Rosa had 1,000 foxes on each island. On San Miguel, there were 400 foxes. By 1999, island fox numbers on San Miguel and Santa Rosa dropped to 15 foxes on each island, and fewer than 50 on Santa Cruz. Because island foxes on each of those islands are physically and genetically different, it was possible a subspecies could be lost forever.
After a decade of captive breeding and no aerial predators around, island fox numbers have skyrocketed in the wild to 1,000 on Santa Cruz, 400 on Santa Rosa and 320 on San Miguel, according to biologists. It’s believed to be one of the swiftest recoveries in the history of the Endangered Species Act.
To keep tabs on their continued recovery, 50 island foxes have been radio collared on each island.
“That gives us a good look at how they survive,” Coonan said. “It’s a safeguard against potential dangers.”