UC Santa Barbara

The Channel Islands foxes are a popular conservation success story after managers, scientists, and zookeepers worked together to remove non-native predators, restore native habitat, and facilitate on-island captive breeding programs. However, although other island fox populations have recovered well, this success story may have been told too soon for the San Miguel Island (SMI) fox. This population experienced a decline of more than 70% between 2015 and 2018 and has been slow to recover since. This decline is attributed, in large part, to parasitism. Notably, a recently identified acanthocephalan parasite, Pachysentis canicola, has drawn considerable attention from Channel Islands National Park (CINP) managers. This parasite has not been detected on other California Channel Islands (CCI) or in mainland California canids, and little is known about the ecology of other helminth species that infect the SMI fox. Here, we sought to 1) describe the helminth assemblage of SMI foxes and the biogeographical patterns of parasitism across the CCI; 2) compare traditional methods of detecting infected foxes with new molecular DNA metabarcoding techniques; and 3) determine the spatial and temporal distribution of fox parasites. In addition to recording seven species of fox parasites, we successfully detected parasite DNA as well as DNA from prey items that may facilitate transmission using scat metabarcoding. Further, we established a baseline for the effects of temperature, rainfall, and habitat type on the prevalence and densities of parasite eggs across the island. The CINP needs a conservation plan to prevent parasite-induced extinction of the San Miguel Island fox, a vulnerable and charismatic species that exists nowhere else in the world. My dissertation provides a foundation for combining traditional and novel tools for managing wildlife threatened by emerging infectious diseases.