Twelve years after being put on the endangered species list, three subspecies of Channel Island fox are no longer considered to be on the verge of extinction, in what the U.S. Fish and Wildlife Service is calling the fastest recovery of a mammal in the 43-year history of the Endangered Species Act. A fourth subspecies that had been listed as endangered has been upgraded to threatened.
Fish and Wildlife designated four of the six Channel Islands fox subspecies as endangered in 2004. The three that populate San Miguel, Santa Cruz and Santa Rosa islands have recovered sufficiently to be removed from the list, the agency said Thursday. Fish and Wildlife upgraded the status of the subspecies that lives on Catalina Island from endangered to threatened.
"The Island Fox recovery is an incredible success story about the power of partnerships and the ability of collaborative conservation to correct course for a species on the brink of extinction," said U.S. Interior Secretary Sally Jewell.
In 1999, there were fewer than 100 foxes on San Miguel, Santa Cruz and Santa Rosa combined, according to Fish and Wildlife. By 2015, that number had climbed to about 4,000.
The story of the foxes' decline and revival involves pigs, eagles, canine distemper and the dogged work of a team of dedicated scientists.
The foxes had been fixtures on the islands for years, according to wildlife biologist Tim Coonan, who worked for the National Park Service on the islands from 1990 until 2015. Around 1995 Coonan and his colleagues noticed fewer foxes showing up in their traps on the northern islands, Santa Cruz, San Miguel and Santa Rosa.
"We started looking at possible causes for decline," he said. The foxes weren't dying off because of disease and food sources were plentiful. What the scientists, and the unsuspecting foxes, didn't count on was death raining down from above.
Coonan and his colleagues attached radio collars to foxes on San Miguel in 1998.
"Within two months, half of our radio collared foxes had died," he said. They eventually determined that golden eagles, a nonnative species, had begun nesting and breeding on the islands - and with scary efficiency, picking off the foxes one by one.
The eagles initially came to feast on the young of the wild pigs and deer. The pigs were introduced to the islands in the 1800s and the deer in the early 1900s to be hunted by humans. But as they proliferated they destroyed the ecology of the natural fauna, which had served to protect the foxes from aerial attacks.
Bald eagles, island natives that don't hunt foxes and are territorial, might have helped prevent the golden eagles from taking hold. But the bald eagle population was ravaged by the dumping of DDT and human interference, increasing the foxes' vulnerability.
"It was almost a perfect storm of events that led to their almost extinction," said Coonan. "They did not evolve with a serious daytime predator like the golden eagle ... Really nothing kills an island fox... and they never learned to look for death coming from the sky. It was not in their evolutionary history at all. They were vulnerable that way."
By 1999, the fox population on Santa Cruz Island had dropped to about 55, according to Fish and Wildlife. Things were worse on San Miguel and Santa Rosa islands, which each saw their number of foxes dip to about 15.
Meanwhile, Coonan and his colleagues noticed that the population of foxes on Santa Catalina Island had dropped to a low of 103 because of an outbreak of canine distemper.
It was another five years before Fish and Wildlife put the four subspecies of island fox on the endangered list. But Coonan and his colleagues from public agencies and private groups didn't wait for the government to act; they began emergency recovery operations years before the foxes were official designated as endangered.
The scientists began vaccinating fox populations against the virus that had wiped out those on Catalina. They hired hunters to rid the islands of wild boar and deer. And they started relocating the islands' 44 golden eagles to northern California.
By adding the foxes to the endangered species list in 2004, Fish and Wildlife afforded them additional protections, and freed up federal dollars to support the coordinated recovery efforts carried out by public agencies and private organizations.
But the key to the recovery process was a captive breeding program, said Coonan. Once the foxes could breed without the threat of predators, they became quite prolific. But since they were starting with so few foxes to breed, one of the scientists' main concerns became inbreeding.
"On San Miguel we had 15 foxes - only four of those were male," said Coonan. "Only two of those foxes ever bred. So all ... foxes that are on San Miguel are descended from two males. And yes, they went through a bottleneck at that point. But there are no signs of inbreeding."
The recovery efforts have helped the fox populations to thrive. By 2015, San Miguel had an estimated 700 foxes, Santa Rosa about 1,200 and Santa Cruz roughly 2,100. Those robust numbers persuaded Fish and Wildlife that it could remove the foxes from the endangered species list.
On Catalina the population grew to about 1,800 by 2015, but the agency continues to list them as threatened because the risk of disease is still high. Biologists are still vaccinating the foxes and watching their population numbers closely.
Fish and Wildlife currently lists about 700 animals as endangered or threatened. It has removed a total of 37 from the list in the history of the Endangered Species Act.
It's rare for species to be removed from the list, much less within 12 years, said Dan Ashe, director of the U.S. Fish and Wildlife Service.
"We're learning how to accelerate recovery," he said, "and a lot of that is how to build the partnerships, how to do the science and how to prioritize the work."
One of the biggest limiting factors when it comes to helping species recover is money, he said.
But in the case of the Channel Islands fox the swift recovery also had to do with location.
"We are in a very unique situation when it comes to recovering a species in this situation because of the nature of an island ecosystem," said Robert McMorran a biologist at Fish and Wildlife.
"On the mainland you always have these constant external pressures that are kind of just right there at your door waiting to move in," he said. "With an island ecosystem you can actually address the threat and have some comfort that you're not going to have that continual pressure ... because it is so isolated."
"This is one in the win column and that just feels great," said wildlife biologist Coonan. "Because if we can do this here, you can do it in other places ... it's an affirmation that cooperative conservation works."
Fish and Wildlife will continue to monitor the foxes on all of the islands, and it has put protocols in place to address any population problems that may arise.
The agency said that the foxes will be officially removed from the endangered species list in one month.