The American Pika (Ochotona princeps) is a small mammal found in broken rock formations, typically at high elevations. Pikas have received considerable attention within the context of climate change due to their intolerance of high temperatures. Numerous local extinctions have been documented in the past century, primarily within the lower, drier, and more geographically isolated Great Basin ecoregion. Despite the abundance of pika research, little is known about their intestinal parasites and the relationship between diet, parasites, and population vulnerability. Using a DNA metabarcoding approach, we are characterizing the summer diets and intestinal nematode communities of pikas in two distinct ecoregions: the northwestern Great Basin in Nevada and the high-elevation Southern Sierras in California. Additionally, we are comparing the frequency of food items in pika diets to the abundance of available vegetation, determined through systematic vegetation surveys, to quantify selectivity and evaluate forage quality. We will synthesize these results with a concurrent study on pika population genetics to look for covariation among pika genetic diversity, diet, and parasitism. We hypothesize that populations with greater genetic diversity and higher quality diets will have fewer intestinal nematodes, therefore we predict that nematode prevalence and diversity will be greater in the Great Basin.