|
Island foxes, the only carnivores endemic to California, have been distinguished from foxes on the mainland by 16,000 years of evolution — ever since they colonized the modern-day Channel Islands, which were then a single, big land mass. As ocean levels rose and this super-island split into eight smaller isles, so began further island fox evolution, eventually dividing the species into six unique subspecies. But though this little, lovable canine pre-dates the invention of the wheel, it’s now threatened by the invasion of humans, their pets, and nonnative animals. Four of the six fox subspecies are endangered, and their habitats still aren’t federally protected.
ENDANGERED SPECIES ACT PROFILE
PROTECTION STATUS: Endangered
YEAR LISTED: 2004
CRITICAL HABITAT: None
RECOVERY PLAN: None
RANGE: The Channel Islands off the southern California coast
THREATS: Predation by invasive golden eagles, canine distemper transmitted by domestic dogs, habitat fragmentation due to development, and habitat degradation due to introduced livestock and nonnative game species
POPULATION TREND: The island fox declined catastrophically from the mid-1990s to the end of the century, but due to captive breeding, relocation of golden eagles, and reintroduction of bald eagles, the populations of its subspecies have since grown. The San Miguel island population went from 450 in 1994 to 15 in 1999, growing to 40 wild and 26 captive foxes by 2005; Santa Cruz Island foxes declined from 1,465 in 1994 to 60 in 2001, but had become 150 wild and 62 captive foxes by 2005; the Santa Rosa Island population declined from 1,780 in 1994 to 14 in 1999, with numbers rising to 32 wild and 34 captive foxes by 2005. Though the population of the Santa Catalina Island fox has been studied only intermittently, sightings had dramatically declined by the summer of 1999; the subspecies’ population has increased since its 2004 listing.
|
SAVING THE ISLAND FOX
Natural selection and a process called “island dwarfing” have made the island fox the smallest fox in the United States, specially adapted to live off the Channel Islands’ limited resources. But its small size makes it especially vulnerable to predation by golden eagles, which feed on the Channel Islands’ feral pigs and began to make their devastating impact on the fox in the ’90s due to the DDT-caused decline of their bald eagle competitors. The complete removal of golden eagles from the islands may be the only thing that can save three of six island fox subspecies. Further, because island foxes are isolated, they have no immunity to the parasites and diseases introduced to the islands by people’s pet dogs — in 1998, a canine distemper outbreak killed about 90 percent of Santa Catalina Island’s fox population. Finally, the foxes are threatened by diminished food supply and habitat fragmentation and loss due to development and introduced mammal species, including feral cats, pigs, sheep, and goats.
To address all of these threats, in 2000 the Center and the Institute for Wildlife Studies petitioned the U.S. Fish and Wildlife Service for Endangered Species Act protection for four of the six island fox subspecies: the San Miguel Island fox (Urocyon littoralis littoralis), the Santa Rosa Island fox (Urocyon littoralis santarosae), the Santa Cruz Island fox (Urocyon littoralis santacruzae), and the San Clemente Island fox (Urocyon littoralis clementae). Despite a Center lawsuit, the Service refused to process the petition until after a 2001 agreement to expedite protection for the fox and 28 other imperiled species. In 2004, after more Center litigation, the Service finally listed all four imperiled fox subspecies as endangered. But the next year it refused to designate and protect critical habitat, stating that because the fox is a habitat generalist — using its entire island range as habitat — there isn’t any specific habitat meeting the criteria for designation.
Thanks to captive-breeding programs, golden-eagle relocations, and bald-eagle reintroductions, island fox populations were on the increase by 2005, and continue to rise. Efforts to remove feral pigs from the Channel Islands are underway, and a vaccination program has been initiated to protect Santa Catalina Island foxes from canine distemper. In 2007, breeding pens were taken down when the San Miguel Island fox population reached 115, and just months afterward, the fox population on Santa Cruz Island had reached about 300 — enough to end the breeding program there as well. Biologists are hopeful that numbers will continue to rise on all the islands, and that the fox will thrive enough to be delisted within five years. But without critical habitat, the island fox must be under constant and close supervision to counteract the ongoing threat of human encroachment on its home turf. The Center will continue to watchdog the threats to this canine.
ACTION TIMELINE
+ CAMPAIGN LINKS
NATURAL HISTORY
+ MEDIA
Contact: Kierán Suckling
|
