Written by Will Huebner on behalf of the Santa Barbara Zoo
A harmonious ecosystem is a delicate thing. Like the surface of a perfectly still pond, the drop of a single pebble can send ripples through the water with tremendous reach. Small changes to the environment can lead to impactful destabilization. Channel Island residents and one of the smallest canids in the world were not immune to this balance shift.
Image courtesy of National Parks Service
The ultimate comeback canids
What happened to the Channel Island Fox?
During an island fox trapping session in August of 1998, biologists uncovered empty trap after empty trap and quickly realized that San Miguel Island’s ecosystem was out of balance.
In the 1990s, the foxes of the Channel Islands off the coast of Southern California suffered a catastrophic population decline. After sustainably inhabiting the Islands for more than 10,000 years, the island foxes experienced an ecosystem unbalancing that unexpectedly started decades earlier.
DDT and the Channel Island fox
In the 1940s, DDT was a pesticide used to kill mosquitos and stop the spread of malaria. DDT was, at the time, “proven” to be as safe as it was effective and inexpensive to manufacture. Fortunately, we know better now. Unfortunately, Southern California was then the center of DDT production in the United States and the pesticide’s use was widespread.
Commonly sprayed on crops and at beaches in significant quantities, DDT washed into the ocean and accumulated in the environment until its use was banned by the Environmental Protection Agency in 1972. After the ban, this accumulation was further accelerated by the illegal dumping of millions of pounds worth of DDT in barrels directly into the sea. As a result, aquatic plants and fish absorbed the lingering DDT and its damage was as good as done.
Bald eagles and the Channel Island fox
Enter the majestic American bald eagle and its steady seafood diet. Feasting on DDT-contaminated fish, bald eagles local to the Channel Islands also absorbed the pesticide. The eagles’ eggshells thinned as a result of their accumulated DDT absorption and their reproduction was disrupted so much that the birds were extirpated (locally extinct) on the Islands by 1960.
Bald eagles were nowhere to be found on San Miguel, Santa Rosa, and Santa Cruz Islands and mainland golden eagles swooped in. These birds of prey share a number of similarities with bald eagles, including approximate size and flight patterns. Golden eagles, however, enjoy a diet of medium-sized mammals…like island foxes.
Island foxes had coexisted with bald eagles for thousands of years and never evolved to fear an aerial threat. Their new avian apex predator island coinhabitants quickly took advantage of their prey’s ignorance and by 1999, a mere 15 foxes survived on San Miguel and Santa Rosa, and less than 80 foxes remained on Santa Cruz.
Meanwhile, on the southern Santa Catalina Island, island foxes faced imminent destruction from another cause: a masked stowaway. It’s believed that a wild North American raccoon hitched a ride on a boat and escaped onto the island in 1998. It carried and spread the canine distemper virus (CDV) to the local fox population. Incurable and often fatal, CDV claimed the lives of more than 90% of the Catalina Island fox population by 2001.
Image courtesy of Santa Barbara Zoo
Saving the Channel Island fox
Conservation groups take action
Island foxes needed help, and they needed help fast! With the housecat-sized canids facing extinction, biologists petitioned the U.S. Fish and Wildlife Service (USFWS) for an emergency listing, requesting the island fox to be listed as endangered under the Endangered Species Act (ESA). They also brought the plight of the island foxes to the attention of their agency, the National Park Service (NPS). NPS was quick to convene a working group of island fox and raptor biologists, wildlife disease experts, and agency staff to summarize what they knew about the island fox’s dire straits and suggest a way to correct course.
In April of 1999, what would eventually become known as the Island Fox Conservation Working Group advised NPS on a multifaceted recovery program aiming to save the foxes from certain extinction. The plan: Have USFWS officially designate the island fox as Endangered under the Federal Endangered Species Act, bring all remaining island foxes into captivity, capture and relocate the golden eagles, and repopulate the Channel Islands with bald eagles.
Channel Island fox captive breeding
With a plan in place, a great collaborative effort was underway! First, the foxes had to be captured. These wily canids were, not surprisingly, less than cooperative. They had to be lured into traps with their favorite treat: wet and dry cat food. The foxes proved picky eaters in this regard and seemed to turn their noses up at low-fat varieties of feline chow. On San Miguel, 14 of the 15 remaining wild foxes were finally brought into captivity in the fall of 1999. The last one, a lone female, cleverly evaded capture until 2003 despite conservationists’ many attempts!
Captive breeding pens had to be constructed on the Islands to protect the foxes from golden eagle predation and to create a monitorable environment for breeding. These were made out of chain-link fencing attached to tubular frames. It quickly became clear that these pens would need roofs as the foxes revealed themselves to be exceptional climbers. On Santa Catalina, one fox in particular climbed to the netted ceiling of its pen as soon as it was introduced to the space and attempted to chew its way out. An impressive feat, but unideal!
Image courtesy of Santa Barbara Zoo
Santa Barbara Zoo joins in to save the island fox
By 2001, it became clear that the captive breeding program required expanding, and the Santa Barbara Zoo joined the recovery effort. Island foxes had never been bred in captivity before, but the Zoo’s animal care and conservation staff happily jumped in with what husbandry and veterinary expertise they had. Working with conservationists on the Islands, Zoo personnel began establishing specific caretaking protocols and best practices for the species.
The Zoo helped formulate a basic diet for the captive foxes, the basis of which was high-quality dry dog food. This was supplemented with hard-boiled eggs, fruits, and vegetables. The foxes’ diet was revised several times through a process of development at the Santa Barbara Zoo, and by 2006 the diet featured dog food with less crude protein and fat and further supplementation of calories with mealworms and mice to resolve weight gain issues.
Additional infrastructure was built to bolster the recovery effort. Small hospitals (affectionately nicknamed “foxpitals”) were built on the Islands and video monitoring systems were installed to help detect and diagnose problems along the way.
One impediment to captive breeding success in zoo environments was stress. Once again, Zoo personnel were able to contribute strategies that mitigated the foxes’ stress. The pens were modified to feature multiple sliding drawers that allowed for food and water to be introduced to the foxes without the caretakers being seen, which also limited altercations over a single food source. Live prey was also given to the foxes this way as a means of stimulating enrichment. Increased pairing options and the introduction of multiple den boxes for female foxes to use also helped the captive critters settle into their pens.
Ultimately, the captive breeding program was an absolute success. The island fox subspecies on San Miguel and Santa Rosa had been crushed down to 15 individuals by the year 2000. By 2009, their populations exploded back to 400+ individuals due to captive breeding and release back into the wild. In less than a decade, all phases of the island fox recovery program had been executed or were in progress. The island fox was well on its way back from the brink!
A foxier future for the island fox
Ecosystems are malleable. Environmental conditions are constantly changing and flora and fauna continuously adapt to different circumstances. Natural extinction events do occur and can even be categorized as positive for the bigger picture of life on Earth (Jurassic Park, anyone?). However, we owe an ethical debt to our ecosystems when the ripple effects of manmade environmental disasters wreak havoc on nature.
The speed at which the island fox recovered from near extinction is a testament to the prudent work of the Island Fox Conservation Working Group. Their successful recommendation for, implementation of, and refinement to recovery actions towards the delisting of the island fox not only provides a proven blueprint for effective, collaborative conservation work, it serves as tangible inspiration. When mistakes are made and disaster strikes, the dedication and teamwork of expert stewards to our natural world can make a difference. And the hard work does pay off.
Mutual of Omaha’s Wild Kingdom Protecting the Wild featured this incredible work to save the Channel Island Fox in our season one episode, “The Lost Fox of Channel Islands.” Watch the clip and get the full streaming link here.
