The last 10 of one of America’s rarest mammals, the endangered island fox, were released from a captive breeding facility on Santa Cruz Island earlier this month. The house cat-sized apex predator of the Channel Islands National Park had been captive-bred on the largest of California’s Channel Islands since 2002.
Golden eagles, drawn to the most biologically diverse islet in the chain by its 5,000-strong feral pig population, nearly wiped out island fox populations across the northern archipelago. The number of island foxes on San Miguel Island fell to just 15 from 400, while the numbers on Santa Rosa and Santa Cruz islands plummeted to fewer than 100 each from 1,000 and 1,500, respectively.
“For island ecosystems, it’s easy to upset the apple cart,” said Tim Coonan, terrestrial biologist at the national park. “We’re using radio collars because we want to know if there’s a catastrophe. We’ll be monitoring them for the next decade.”
An aggressive captive breeding program led by the National Park Service, The Nature Conservancy, Institute for Wildlife Studies and the U.S. Fish and Wildlife Service, has brought the wild populations back from the brink of extinction.
“Partnerships are what made it work,” said Russell Galipeau, superintendent of the Channel Islands National Park. “To recover this endangered species, we feel we’re protecting our American values.”
Historically, there were 1,500 foxes on Santa Cruz, 1,200 on Santa Rosa and 400 on San Miguel. Currently, there are 300 of the tree-climbing foxes on Santa Cruz and 115 on San Miguel. Captive breeding has been slow on Santa Rosa, and the wild population is low. For now, captive breeding will continue on the windswept island. About 25 percent to 30 percent of the fox population is radio-collared on Santa Cruz.
“We’re shooting for 1,500 foxes on Santa Cruz,” said Dr. Lotus Vermeer, the Santa Cruz Island director for TNC.
The last of the feral pigs were eradicated last spring. Pro Hunt Inc., a New Zealand company that specializes in removing non-native species, spent two years on the $5 million pig project. This eliminated the food source for golden eagles, and the last known nesting pair was removed in 2006. All the golden eagles were trapped and transported to the mainland. They were radio-collared and none have returned.
“We’ve removed their major stressor and the foxes are going crazy, which is good,” said Coonan. “We’ve moved them away from extinction.”
In turn, 61 bald eagles have been returned to the rugged national park since 2002, after a 50-year absence from their historical nesting habitat. About 35 still reside on the island with three nests in the last two years successfully hatching for the first time since 1949. Bald eagles are generally more aggressive than golden eagles, and they’ll defend a territory against competitors. Bald eagles eat fish, not island foxes. The NPS expects there to be at least five or six bald eagle pairs nesting on the chain in 2008.
“The island fox was the African lion of the Channel Islands until the golden eagles showed up, and then it became a prey item,” explained Dave Garcelon of the IWS. “We’re returning the system to a little more of a balance. I think this species will be off the endangered species list in record time.”
As each tiny, cinnamon-colored island fox was released, few left their cages in a hurry. The submissive creatures had to be coaxed out of their enclosures. One had to literally be picked up by Garcelon and placed on the ground, before it scurried down a dirt track and bounded off into the wide open spaces of Santa Cruz.
“This is an exciting time on Santa Cruz to witness this milestone of the recovery of these diminutive foxes,” continued Vermeer. “This marks the closure of captive breeding on the island.”
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