By AnaRose Hebein, S25 Environmental Clinic Student
As more species face extinction than ever before, we can carry forward the lessons from the decline and subsequent recovery of the Channel Island fox—lessons learned from the interconnected causes of their decline to the monumental (and ultimately successful) efforts to save these charming foxes from the brink of extinction. The story starts in the 1990s, when four of the six subspecies of the Channel Island fox faced significant declines.[1] By 2001, the International Union for Conservation of Nature classified the species as “Critically Endangered,” and by 2004, the U.S. Fish and Wildlife Service (USFWS) listed four subspecies as “Endangered” under the Endangered Species Act. The Santa Cruz Island population dropped from 1,450 foxes to only 55, while the San Miguel and Santa Rosa Island subspecies plummeted from 450 members and 1,750 members (respectively) to just 15 each. The Santa Catalina Island population also declined sharply from 1,300 to only 103.
As part of its recovery plan, USFWS examined threats to the species.Interestingly, the forces that led to the declines in the Channel Island foxes began many years before, when DDT use was widespread.[2] The USFWS suspected that the subspecies’ declines were linked to the declines in bald eagles. Bald eagles were once common on the islands, but by 1960, none remained on the islands because of nest failures caused by the pesticide DDT, which weakened their eggshells and caused their eggs to fail to hatch. This left the habitat open to a non-native bird of prey: the golden eagle. Unlike bald eagles, which typically hunt fish, the golden eagle hunts mammals and began to decimate the Channel Island fox populations, particularly because the island-dwelling foxes have no natural predators. The decline of the Santa Catalina Island subspecies was further affected by an outbreak of Canine Distemper Virus (CDV), and USFWS determined that all Channel Island foxes could be severely impacted by CDV or by rabies, should either disease infect any of the islands’ inhabitants.
To combat these threats, USFWS began captive breeding and reintroduction programs on each island. In addition, USFWS removed golden eagles and their non-native sources of prey (like feral hogs) from the islands. The USFWS continued existing efforts to reintroduce bald eagles and hypothesized that the presence of nesting bald eagles, which are territorial, would deter recolonization of the island by golden eagles.
As a result of these efforts, the Channel Island foxes recovered faster than any mammal ever listed as endangered, and USFWS delisted three of the subspecies in 2016.[3] Even with this historic success, the Channel Island foxes are subject to annual vaccination and ongoing monitoring by physical trapping, aerial radio telemetry, and GPS tracking.
The recovery of the Channel Island fox is both a model and a reminder of the good that the Endangered Species Act can do when comprehensive, large-scale efforts are undertaken. When Congress passed the Endangered Species Act with bipartisan support over fifty years ago, it envisioned these types of remarkable and comprehensive efforts.[4] Not only does such an incredible recovery provide hope, but it also should provide a model for the conservation efforts required to successfully delist other, less charismatic critters. Furthermore, this recovery shows the importance of recognizing the interrelated nature of environmental problems and the necessity of large-scale, intensive interventions to protect endangered species.
[1] U.S. Fish & Wildlife Serv., Recovery Plan for Four Subspecies of Island Fox 1 (2015), https://ecos.fws.gov/docs/recovery_plan/Recovery%20Plan%20for%20Four%20Subspecies%20of%20Island%20Fox_2-27-15%20final.pdf.
[2] Stanley N. Wiemeyer et al., Organochlorine Pesticide, Polychlorobiphenyl, and Mercury Residues in Bald Eagle Eggs—1969–79—and Their Relationships to Shell Thinning and Reproduction, 13 Arch. Env’t Contam. Toxicol. 529, 529-49 (1984).
[3] U.S. Department of the Interior, Interior announces fastest successful recovery of an endangered species act-listed mammal; three Island fox subspecies now fully delisted (2016), https://www.doi.gov/pressreleases/interior-announces-fastest-successful-recovery-endangered-species-act-listed-mammal.
[4] 16 U.S.C. § 1531; U.S. Department of the Interior, Celebrating 50 Years of Success in Wildlife Conservation (2023), https://www.doi.gov/blog/endangered-species-act-celebrating-50-years-success-wildlife-conservation.