If you come out to Santa Cruz Island today, you’re virtually guaranteed to see an endangered island fox, the little rascals bounding across the largest of California’s Channel Islands. That wasn’t the case 15 years ago when the chain’s largest land mammal teetered on the brink of extinction.
Today there are approximately 1,200 island foxes enjoying the most biodiverse island off the California coast. In 1999 roughly 55 island foxes were looking over their shoulders wary that their time was up. Back then a 5,000-strong feral pig population was responsible for luring over 40 golden eagles that had colonized the northern islands of the Channel Islands National Park Service (NPS). Taking advantage of the absence of bald eagles due to DDT poisoning, golden eagles soon realized it was easier to hunt island foxes than the scruffy swine.
The island fox populations on Santa Rosa and San Miguel Islands also plummeted due to golden eagle predation. Because the two island fox populations are both subspecies of the Channel Islands fox, if either population were lost then that subspecies would be gone forever.
Conservation partners such as the NPS, The Nature Conservancy, the Institute for Wildlife Studies and the U.S. Fish and Wildlife Service (USFWS) implemented immediate conservation actions to address those threats and prevent the extinction of the island fox. A captive breeding program was initiated in 1999 on each island and played an integral role in recovery efforts. The program ended in 2008. All captive-bred foxes were returned to the wild and vaccinated to prevent the spread of canine distemper. Additionally, golden eagles were trapped and relocated to the California mainland. The feral pig population was eradicated on Santa Cruz Island, and bald eagles were re-established in their historic territories.
Extinct from the islands since the 1960s, bald eagles are now thriving after aggressive restoration efforts began in the National Park in 2002 with 12 bald eagles released each year through 2006. A recent NPS report said there are now 50 bald eagles living in the park. Combined with Catalina, California’s Channel Islands recently reached an important milestone with the 100th bald eaglet expected soon to fledge. There could also be a record 20 active bald eagle nests across the Channel Islands this breeding season.
Because DDT pesticides are still prevalent near Catalina Island, restoration efforts there require biologists to lend a hand in the incubation process. That’s not the case in the National Park where DDT is less prevalent in the food web, enabling bald eagles to hatch their eggs on their own. The restoration of bald eagles has been especially vital, because they’ve helped keep golden eagles at bay. Bald eagles scavenge marine mammal carcasses and hunt fish, not island foxes.
“The recovery of the island fox has the potential to be the fastest recovery of any land mammal in the history of the Endangered Species Act,” said biologist Robert McMorran of the U.S. Fish and Wildlife Service.
McMorran also said it would probably be a couple of years until the island fox is delisted. A proposal for delisting involves a status review, analyzing any new information and public comment, among other protocols.
In the meantime, island fox populations across the northern chain are enjoying their return to a natural balance. In 1999 island fox populations on Santa Rosa and San Miguel Islands were 15 on each island, making captive breeding a real challenge to avoid any inbreeding. Today San Miguel Island is brimming with island foxes and is currently at carrying capacity of approximately 500 animals. Santa Rosa Island is a bit larger than its neighbor to the northwest and still has some room for more of the cinnamon-colored foxes. Historically, Santa Rosa carried about 1,000 foxes. Today the population is around 700.
“The San Miguel population is putting itself back in check,” continued McMorran, who has been working on island fox recovery for the USFWS since 2007. “It can only harbor so many foxes.”
Even though populations are robust, conservation partners aren’t taking any chances. Captive breeding facilities remain on each island just in case of possible threats to island fox populations.
“If there are depressed population numbers due to golden eagles or canine distemper, then epidemic response plans are already in place,” McMorran said.