Pollution and parasitism in coyotes of the Puget Sound region

Abstract

Urban ecosystems are complex social-ecological systems where wildlife are exposed to a mosaic of interacting stressors, including habitat fragmentation, novel food resources, and persistent environmental contaminants. However, urban ecology studies often overlook a crucial hidden player: parasites, which can reflect effects of anthropogenic stressors in their hosts and serve as bioindicators for contamination. While parasites impact their hosts’ health, and their hosts’ health is impacted by the environment, few urban wildlife studies consider how the environment in turn impacts parasites. Coyotes (Canis latrans), as mesocarnivores that inhabit a range of urban-rural gradients across North America, provide a unique lens through which to examine these ecological and physiological dynamics. In my dissertation, I sought to determine how human-driven environmental pressures shape wildlife and parasite populations in the Puget Sound region, Washington State, USA, using coyotes as a model species. In Chapter 1, I examined how environmental contamination contributes to the structure of mammalian diversity and mesocarnivore activity across the Seattle-Tacoma metropolitan region. This chapter integrated spatial contaminant data with camera trap surveys and revealed that, while environmental contamination has an overall negative impact on mammal communities, responses are species-specific: coyote detections were negatively affected by environmental contamination, while detections of raccoons and opossums were not. In Chapter 2, I further identify connections between the environment and wildlife by investigating contamination at an organismal scale. Using salvaged coyote carcasses, I quantified trace metal concentrations in tissues of coyotes and their gastrointestinal helminth parasites, finding that parasites bioaccumulate metals at higher concentrations than their hosts and revealing a potential silver lining of parasite infection. In Chapter 3, I applied morphological and molecular techniques to coyote carcasses and field-collected scats and discovered the zoonotic cestode Echinococcus multilocularis in coyotes across western Washington state — the first record of this parasite in a wild host in the region. These findings highlight the crucial gaps in and public health relevance of our understanding of wildlife parasite distributions. In Chapter 4, I modeled the ecological drivers of distribution of E. multilocularis as well as two other gastrointestinal parasites, Taenia pisiformis and strongylid hookworms, in coyotes. I showed that both individual coyote diet and urbanization influence parasite distribution, but that the strength and direction of these influences depended on parasite species traits. This dissertation elucidates the impacts of environmental contamination on urban wildlife, advances understanding of parasite ecology in human-altered systems, and positions coyotes as sentinels for environmental contamination and zoonotic disease.