Effects of urbanization on diet in eastern chipmunks (<i>Tamias striatus</i>) as determined by stable isotopes

Urban environments offer wildlife a consistent supply of anthropogenic food waste, divergent from natural food sources in nutrient composition. This study investigates the dietary impact of urbanization on eastern chipmunks ( Tamias striatus (Linnaeus, 1758)) by analyzing stable isotope signatures (∂13C and ∂15N) in their hair. The hypothesis posits that chipmunks in urban locales consume more corn-based and high-protein foods, reflected in elevated isotopic signatures compared to their rural counterparts. Sampling encompassed 20 sites across Sudbury, Ontario, varying in urbanization levels. Urbanization was gauged via surveys capturing human activity and sources of anthropogenic food waste. Contrary to expectations, chipmunks did not exhibit δ13C signatures indicative of substantial corn consumption from human food waste. However, δ15N signatures positively correlated with urbanization, suggesting heightened animal protein intake in urban habitats. Elevated δ15N signatures may also result from the use of fertilizers in urban areas. Future avenues involve using stable isotope mixing models to pinpoint dietary sources and exploring the health and reproductive ramifications of urban diets, including effects on gut microbiome composition.