Outfoxing Extinction

How the Channel Island fox made the fastest recovery of any mammal ever placed on the endangered-species list

By Jason Daley

August 19, 2016

Channel Island foxes

Channel Island foxes | Photo by Chuck Graham

Things looked grim in 2004 for the Channel Island fox (Urocyon littoralis), a small species of canid found nowhere on Earth outside six of California’s eight Channel Islands. The U.S. Fish and Wildlife Service reports that the fox numbers plummeted almost 90 percent beginning in the 1990s. On Santa Rosa Island, the population crashed from 1,750 to just 15. San Miguel had only 15 left, down from 450. Catalina and Santa Cruz Islands experienced similar drops. Researchers gave the fox, which has a unique subspecies on each island, a 50 percent chance of going extinct over the following decade.

It didn’t.

The island fox has made the fastest recovery of any mammal ever placed on the endangered-species list, with over 5,000 of the animals roaming the Channel Islands since 2015. As of last week, three of the subspecies are now off the endangered list completely; the Catalina Island foxes remain listed because of the dogs that visit the island, which can bring diseases like canine distemper. It’s no fluke of nature—the speedy recovery came about because a consortium of conservationists informed by strong science put their backs into the effort.

“That’s the power of the ESA—not just to protect rare animals and plants on paper, but to drive focused conservation that gets dramatic results,” Fish and Wildlife Service director Dan Ashe said in a statement. “More than 300 experts, nonprofit organizations, state and federal agencies came together to not only prevent the extinction of Channel Island foxes, but to fully restore them in record time. That’s something to celebrate!”

The fox was a victim of unintended consequences. Ranchers, who inhabited the islands in the early 20th century, imported nonnative animals to the archipelago. Wild cattle and sheep grazed the vegetation the foxes use for cover. On Santa Rosa, imported deer and elk browsed down native plants. That was especially dangerous for the cat-size foxes. DDT wiped out the local population of bald eagles, which scavenge and eat fish. In their absence, golden eagles moved in and began preying on the foxes, which now had little cover under which to hide. The eagles took their toll, and an outbreak of canine distemper decimated the foxes.

To save the species, a coalition including the National Park Service, the Fish and Wildlife Service, the Nature Conservancy, the Catalina Island Conservancy, the U.S. Navy, and many other scientists came together to share resources and put together the recovery plan.

Over the course of a decade, they removed the feral pigs and sheep as well as the deer and elk; trapped and relocated the golden eagles and re-established bald eagles in the islands. They vaccinated the foxes for distemper and released 226 captive-reared individuals back on the islands.

“I think what enabled this to be so accelerated is that we didn’t do these needed activities in sequence; we did them simultaneously. It was a very intensive effort and an extraordinary amount of work by a bunch of people and institutions and individual scientists contributing ideas,” says Scott Morrison, director of conservation science at the Nature Conservancy in California. “I think what you see in this project is that as quickly as an island can spiral downward it can spiral back upward. What you see here is what can happen when a bunch of people get together and decide they’re not going to let a species go extinct on their watch.”

Morrison says while the collaboration was key, the science side of the equation is what set this project apart, and may have implications for future endangered species management. The team worked with Dan Doak, an environmental studies professor and pioneer in population modeling, and Vickie Bakker, a researcher at Montana State University. Instead of just undertaking tried-and-true conservation techniques, the consortium performed extensive modeling, or “population viability management,” on every project proposed for the foxes to make sure they were using their limited resources properly. If the models did not show the project helped achieve their goal of a 5 percent or less chance of extinction over 50 years, they went back to the drawing board.

For instance, Vickie Bakker says the modeling showed that a plan to monitor a few radio-collared foxes—called “sentinels”—for rabies would likely fail because the disease would spread too fast before it was detected. Instead, the models indicated that capturing and vaccinating a small section of the fox population for rabies in perpetuity would ensure that at least a segment of the foxes survived an outbreak. “Our models showed that extinction risk from rabies was much lower when using prophylactic vaccination to form a protected core group of survivors,” says Bakker, “and also more affordable and logistically feasible than the standard approach.”

Bakker and Doak are now using population viability management on the recovery of California condors and hope the system is adopted for other recovery plans.

As the spotlight turns away from the island fox, Morrison says he does not think the species will face another steep decline any time soon. The restoration efforts have improved the habitat on the Channel Islands, and continued monitoring will make sure the species is doing well. “One other insurance policy is this collaborative effort that has developed over the past 20 years. I don’t see that diffusing,” says Morrison. “The foxes now have the advantage of people accustomed to helping them.”