Voices for Biodiversity

The Remarkable Comeback of the Channel Islands Fox

When I first set foot on Santa Cruz Island, I hadn’t yet heard the story of the island fox and its remarkable recovery. To be honest, I didn’t even know these foxes existed. The first time I saw one, I was struck first by its size — no bigger than a housecat — and then its color, a beautiful palette of grey, red and brown reminiscent of its larger cousin, the mainland gray fox. As I saw more throughout the day, they all seemed curious and playful — I could have happily watched them for hours.

As I would soon learn, the island fox, which is endemic to California’s Channel Islands, is remarkable not only in its appearance, but in its story as well. Teetering on the brink of extinction in the late 1990s, the island fox stands out in the conservation world due to a unique, cooperative effort that resulted in the fastest recovery of an endangered mammal in the history of the Endangered Species Act. From as few as fifteen individuals on some islands, populations had rebounded to pre-decline numbers in just under ten years.

The more I learned about the foxes, the more I wanted to learn.

Setting the Stage
To understand the intricacies and issues faced in the conservation of the island fox, I found it helpful to learn some of the history of the islands and the main players in island management. The Channel Islands archipelago includes eight islands. San Clemente and San Nicolas are managed by the U.S. Navy, while Santa Catalina is privately owned and the only island with a significant permanent civilian population.

Channel Islands National Park is comprised of the remaining five islands — Santa Cruz, Santa Barbara, Santa Rosa, Anacapa and San Miguel — and was designated as a national park in 1980. 

To throw one more player in the mix, Santa Cruz is co-managed by the National Park Service (NPS) and The Nature Conservancy, which purchased the majority of the land on the island from ranchers in 1978 and still manages the western two-thirds. Foxes are found on all the islands except Santa Barbara and Anacapa, which are too small to support natural populations.

From a geological standpoint, one of the most remarkable aspects of these islands is that they have never been part of the mainland, giving the local species the opportunity to evolve in complete isolation. During the last ice age, sea level was significantly lower, meaning the shortest distance between the islands and the mainland was only about four miles (rather than the current 12 miles). The northern Channel Islands, now a group of four separate islands, were once one large island known as Santa Rosae.

The original human inhabitants of the Channel Islands, the Chumash, lived on the islands for millennia. One of the oldest human remains found in North America was excavated on Santa Rosa and dated 13,000 years old.

European settlement on the islands began in 1770 and, through disease transmission, displacement and missionization, the island Chumash population underwent massive declines. By the 1820s, all remaining Chumash had moved to the mainland. For the next 150 years, Europeans dominated the landscape and ushered in an era of ranching on the islands, bringing in sheep, deer, elk and pigs — all of which would end up playing an important role in the story of the island fox.

Although scientists are still not entirely sure how foxes originally arrived on the islands, there are two main theories. One is that the Chumash people brought gray foxes over from the mainland in their tomol, or plank canoes. The other is that foxes “rafted” from the mainland when sea level was lower. From there, rapid evolution and movement by humans led to the current range and species we know as the Channels Islands fox.

“It’s amazing that there are six separate subspecies that developed within 6,000 to 10,000 years — and probably even less — so differentiation has occurred very quickly out on the islands,” says Tim Coonan, a biologist for Channel Islands National Park for 25 years.

For thousands of years, the island fox lived alongside humans. Although ebbs and flows in populations are suspected, no large-scale declines in their population had been recorded in written or oral history.

The Perfect Storm
In 1993, Coonan and other park biologists started trapping foxes and marking them with passive integrated transponder tags, which would stay on for life and give scientists a better understanding of fox biology. After the first year, they had counted over 400 animals on San Miguel Island, but by 1996 they observed a precipitous population drop — a trend that extended to Santa Cruz and Santa Rosa. In response, biologists starting tagging the foxes with mortality collars, radio collars that emit a different signal when the fox hasn’t moved in six hours.

When dead foxes were located, the remains indicated that golden eagle predation was the culprit. But why such a sudden decline? The answer was a fascinating mix of species’ stories interweaving and the impacts this had on the ecosystem overall — something Coonan describes as “a perfect storm of factors” leading to the near-extinction of the island fox. 

About five decades earlier, across the Santa Barbara Channel, DDT production was ramping up in post-World War II America. One of the main producers of the insecticide, Montrose Chemical Corporation, started production in Torrance in 1947. For decades, untreated byproducts from DDT production put as much as 640 pounds of DDT per day into the Los Angeles sewer system, which emptied two miles offshore into the Pacific Ocean. On the Channel Islands, native bald eagle populations were among the many bird species about to suffer from the effects of DDT.

When DDT leached into the waters of the Santa Barbara Channel, the fish that lived there became laden with chemicals. Bald eagles, having predominantly marine-based diets, soon began ingesting DDT when consuming the fish. Rachel Carson famously documented the results in her book Silent Spring — the eagles’ eggshells were paper-thin and shattered with ease. Without any new chicks hatching, bald eagles declined precipitously. By the mid-1950s, the Channel Islands population had been entirely wiped out.

While this keystone species had been eliminated from the island through pollution, other species introduced by humans were undergoing changes of their own. Pigs, first brought to the islands by Europeans in 1850, had become feral. They had undergone a population explosion and were ravaging the islands, destroying important ecological and archaeological sites.

“Pigs were just rototilling the ground out there,” says Coonan. With bald eagles out and more pigs in, the non-native golden eagle had an opening to establish itself on the islands for the first time, using feral pigs as their main food source.

Coonan describes the foxes as an “indirect casualty of a non-native species.” Although feral pigs were the main prey of the newly arrived golden eagles, the foxes were a tasty treat, and they were vulnerable for a number of reasons. Their small size played a role, but so did the fact that they had evolved without predators — from the land or the sky — which left them without predator-avoidance behaviors.

Unlike most foxes, the island fox is primarily active during the day, leaving them highly visible during the eagle’s peak hunting period. Additionally, anthropogenic conversion of native scrublands to non-native grasslands left them with little aerial cover.

Foxes mate for life in territorial pairs (although Coonan admits there is some fooling around at territory boundaries), meaning that the random plucking of individuals by golden eagle predation also caused significant changes in the social hierarchies of the foxes and affected their population dynamics indirectly. “When eagles come in and pick off pairs or members of pairs, it causes all holy hell to erupt socially, because suddenly there are vacant territories or a mate is missing,” says Coonan.

The perfect storm raged on.

Full Crisis Mode
By 1999, San Miguel and Santa Rosa had only 15 foxes left — a decline from an estimated 450 and 1,500 individuals respectively. It was obvious that it was time to act if there was any hope of avoiding extinction.

“When you have 15 animals left in a species or a sub-species,” says Coonan, “that’s pretty much a ‘one foot in the grave’ situation.” It was clear from the outset that the approach would have to be multi-pronged and consider the entire ecosystem.

Biologists also knew that they had no time to waste, “We were well ahead of that federal listing. We had to be,” says Coonan. They had to act immediately and in collaboration. Between 200 and 300 individuals and a range of organizations came together to start implementing a species survival plan that included removing some species, reintroducing others and creating a captive breeding program to ensure the foxes’ long-term survival.

“It was very much a multifaceted restoration effort that really looked at the ecosystem broadly [and tried] to restore balance to the ecosystem in order to save the island fox,” says Yvonne Menard, an interpretive ranger at Channel Islands National Park. While the eventual proposed listing of island foxes as endangered in 2004 did help nonprofits raise funds for conservation efforts, the emergency actions had to be prompt.

Getting to Work
The first step was to trap the remaining foxes and put them in captivity — every day out in the wild was one more day the foxes were available for golden eagle predation. Each fox subspecies had evolved particular features specific to their island, so it was decided that they should not be mixed. Additionally, the threat of exposure to novel diseases from the mainland meant that all captive breeding efforts had to be done on-island.

Genetic testing was done to avoid bottlenecking as much as possible during breeding, which was particularly important on San Miguel, where today all foxes are descendants of the two remaining males of breeding age in 1999. Park biologists worked with zoos and animal behaviorists to figure out how best to feed, support and breed foxes in a captive environment, as well as provide animal enrichment to help stimulate natural behaviors in the animals.

Next, the partners worked to remove the non-native species that were indirectly or directly causing the foxes decline: golden eagles and non-native ungulates. Over the next seven years, sheep, pigs, elk and deer were rounded up and removed from the islands. Between 2005 and 2006 alone, over 4,000 feral pigs were removed by a special team from New Zealand that was brought in for this specific part of the conservation effort. 

While some groups worked on the ungulates, others focused on the golden eagles. Raptor biologists set traps and removed 44 birds in a six-year period. The last golden eagles were removed in 2006 and released in California’s Sierra Nevadas, a native range for the species.

The process of reestablishing bald eagles began in 2001. Eaglets from a breeding pair at the San Francisco Zoo and a wild-capture program in Alaska were released through a process called “hacking” over the next five years. The restoration efforts were funded with the settlement money from the Montrose Chemical Company, who were responsible for their local extinction to begin with.

In 2006, the first breeding pair of bald eagles was observed on the Channel Islands in over five decades. Today, you can watch them on the bald eagle webcam.

Meanwhile, the foxes’ captive breeding program was proving to be a massive success. By 2003, there were enough foxes in captivity to support the release of some of them back into the wild. With the concurrent efforts to remove golden eagles, wild populations rebounded fairly rapidly, and in the next few years were reproducing more in the wild than in captivity. In 2007, less than a decade after conservation efforts began, it was time for the release of all the remaining foxes.

Another Island, Another Threat
While all of this was happening on the northern Channel Islands, a raccoon sneaking onto a boat bound for Santa Catalina Island was about to wreak a different kind of havoc on the fox population of that island.

In 1999, the same year that island fox populations precipitously dropped on the northern Channel Islands due to golden eagle predation, residents of Santa Catalina’s city of Avalon started reporting dead foxes. But golden eagles never established themselves in the southern island group, so here the story took on a different twist. The Catalina Island Conservancy and Institute for Wildlife Studies set traps for foxes and discovered the decline was due to canine distemper virus. Further genetic sequencing showed it was a variant found primarily in mainland raccoons. Highly sensitive to this novel disease, over 90 percent of the foxes had died of the virus in less than a year. The two unrelated declines, eagles in the north and disease in the south, were happening in tandem. In 2000, a captive breeding facility and experimental vaccination program were set up on Santa Catalina. 

Conservation Takes a Village
Today, island fox populations are back at their pre-decline numbers on each of the six islands where they are found. In 2016, the island fox was triumphantly removed from the endangered species list (just a year after the formal federal recovery plan had finally been proposed).

The quick response, multifaceted approach and successful coordination among a large number of organizations and individuals contributed to one of the fastest recoveries of an endangered species ever observed.

“Cooperative conservation has been the hallmark of island fox recovery since day one,” says Coonan, noting the importance of springing into action with a coordinated approach as soon as the problem was recognized. “All the pieces were in place and there were no objections.”

At this point, the major recovery efforts have mostly concluded. Continued conservation will always involve looking to the future: “[Golden] eagles are not going to happen again,” says Coonan, “The balance has shifted. It’s disease. They’re so vulnerable to disease.”

To help curb that possibility, Channel Islands National Parks has instigated a wildlife vaccination campaign on all the islands — something Coonan describes as “very unusual” for the NPS. About 100 foxes on each of the islands were vaccinated for rabies and canine distemper virus. On Santa Catalina, where the presence of dogs and stowaway raccoons presents a higher risk, 300 to 400 foxes were vaccinated. Several other diseases are monitored via blood sampling.

The Visitor’s Role
In 2016, Channel Islands National Park had 364,808 visitors, a 13 percent increase from the previous year. When you include virtual visitors through the park’s Channel Islands Live platform, that number climbs to a massive 10.7 million. Each of these visitors has a role to play in the future conservation of the foxes and the islands overall.

“Island foxes are the top keystone predator, and they are a charismatic mammal,” says Menard. “They’re beautiful in the way the look, they have really cute and curious behaviors, so people are naturally attracted to learn about them. So they’re a great opportunity for us to talk about the balance of an ecosystem. They highlight how we can make a difference.”

When I first arrived on Santa Cruz, my group was taken aside by the park rangers for a briefing on the island, the campground and native species like the foxes. We were told not to feed the foxes and to utilize the “fox box” at each campsite to secure food and other scented items. But it was up to us to listen. Part of being a responsible visitor to the islands means ignoring those cute faces asking you for food. As Menard warns, “It only takes one or two people to have an impact on the population.”

It’s also up to visitors to ensure we don’t introduce new threats. “Islands are especially vulnerable to all kinds of introductions of diseases and pathogens and non-native species,” says Coonan. “So the more the visiting public does to make sure that doesn’t happen, like cleaning their boots off before they get on the boat in Ventura, the better it is. We still have people who bring their dogs out to the islands on boats, and that would be a huge source of pathogens were one of those dogs to encounter an island fox.”

In addition to on-island briefings, there are guided walks and evening events conducted by park rangers that help educate visitors about the fox and the delicate balance of the island ecosystem. On the mainland, there is a visitor center in Ventura, and the park runs a lecture series entitled “Sea to Shore” to further understanding of current research on the Channel Islands and surrounding waters. Staff members are developing an educational curriculum, including a module on the foxes, for grades 6 to 8 and 9 to 12 nationwide. It will align with the Next Generation Science and Common Core State Standards.

All these efforts are heartening and a great example of what long-term, cooperative conservation looks like. From biologists and rangers to educators and visitors, it took a village to save the island fox, and it will take a village to continue protecting them. But the foxes are here to remind us that it can be done.

Photos used with permission from Gemina Garland-Lewis, and cannot be used or reproduced.

Comments