Submitted by Russel Barsh, director, Kwiaht.

On March 7, 1859, Northwest Boundary Survey naturalist C. B. R. Kennerly shot a young female raccoon he observed “fishing on the border of a small fresh water lake” on northwest San Juan Island and shipped its skull and skin back east to the National Museum in Washington, D.C. Kennerly did not encounter any foxes (or bears), but Hudson Bay Company agent Charles Griffin confirmed that wolves had freely roamed San Juan Island until Belle Vue Farm shepherds set out poisoned meat for them a few years earlier. Hence, when Euro-American farmers streamed into the islands in the wake of the American Civil War, raccoons were the largest terrestrial carnivores they had to cope with. It was only in the 1920s-1940s that red foxes were introduced on San Juan Island; their population exploded in the 1960s, about the same time as the first wave of nonfarm residential development altered the islands’ agrarian landscapes — and increased the abundance of nonworking domestic (and feral) dogs.

Through all of these changes, native raccoons have survived, shifting their diet from small wild mammals, nesting birds and invertebrates to thriving in the shadow of human settlements, benefiting from barns, livestock, gardens and orchards, compost heaps, castoff food items and food left outdoors for farm animals and pets. It is unlikely that the introduction of foxes posed much of a challenge for raccoons at first; the introduction of European rabbits in the years leading up to the Great Depression provided feral foxes with an abundance of familiar prey. But the rapid growth of residential nonfarm settlements eventually pushed both raccoons and foxes into closer contact with people, people’s gardens and garbage, and domestic dogs by the 1990s.

The activities of native raccoons, introduced foxes and domestic dogs have now converged on south San Juan Island. All three species are broadly “synanthropic” — which is to say that they tolerate close contact with unfamiliar people (including park visitors), cars and homes, and share adaptations to consuming human food. They can easily come into conflict over a chicken coop, a bowl of dog biscuits or a dead rabbit, potentially resulting in serious injuries. But that is not the whole story or the worst of it. As an ecological triad of carnivores with overlapping diets, raccoons, foxes and domestic dogs are also likely to share a distinct community of parasites and pathogens that they can pass back and forth through saliva, urine and fecal matter.

One shared pathogen is Canine Distemper Virus, which can be managed by vaccination in domestic dogs, while producing rabies-like symptoms and fatalities in unprotected wildlife such as foxes and raccoons. CDV appears to be endemic and cyclical in the islands’ raccoons, leading to periodic, often conspicuous mortality events. Another shared pathogen, detected in a San Juan Island raccoon in 2025, is Canine Parvovirus, which is also manageable in domestic dogs by vaccination but usually fatal in unvaccinated wild foxes and racoons.

People are also at risk from some of the pathogens shared by raccoons, dogs and foxes. Raccoons host a parasitic roundworm, Baylisascaris procyonis, which can infect dogs as well as people through contact with fecal matter. Similarly, the bacterium Leptospyra persists for weeks in soils where infected raccoons or rabbits have urinated; it causes gastric distress in unvaccinated dogs and can result in kidney disease.

We have not yet seen evidence of any significant role of raccoons or foxes in the life cycle of the islands’ native Blacklegged ticks, which are very frequently found on domestic dogs, and may infect their canine hosts with pathogens such as Anaplasma, Mycoplasma and Ehrlichia, all of which nevertheless remain relatively rare in San Juan County. Island dogs, foxes and raccoons may share fleas; however, fleas disperse tapeworms (Dipylidium caninum).

The bottom line is simple: Vaccinate your pets, and keep them separated from wild foxes and raccoons. This includes preventing wildlife from sharing dogs’ food or water bowls, and from “hanging out” around your home, where they can leave fecal matter and urine. On walks, prevent dogs from approaching foxes or raccoons, and from investigating scat piles or dens.

The islands’ native raccoons are clever and often charming, but like our introduced foxes, they unwittingly provide reservoirs for diseases that put pets and people at risk. Enjoy their antics at a respectful distance, in wildlands, with your dogs leashed!