Surviving the concrete jungle: the eco-physiological consequences of consuming anthropogenic food waste on raccoons (Procyon lotor)

Abstract

Urbanization is a process where natural landscapes are transformed to include structures like buildings and roads to accommodate the growing human population. Many species of wildlife are unable to adapt to these rapid and drastic landscape changes, resulting in declines to certain populations. However, species like mesocarnivores that have flexible diets are able to thrive in these urbanized environments due to the increased access to anthropogenic food waste. Food resources such as this are different in both quantity and quality, potentially leading to individual health effects. This research studied the physiological consequences associated with an urban diet in raccoons (Procyon lotor), a species that is opportunistic and omnivorous. Dietary patterns using C and N stable isotope analysis were measured, along with their effect on body condition, glycated serum protein (GSP), and leptin across an urbanization gradient from the Ontario and Québec regions during the fall. Stable isotope analysis revealed δ13C and δ15N were highest in agricultural and barren landscapes, exhibiting a diet highly reliant on C4 plants such as corn and animal protein, respectively, instead of anthropogenic food waste as previous studies with summer sampling periods have shown. Body condition had a positive relationship with both δ13C and leptin, providing evidence that increases in body condition is associated with fat mass. However, extremely high body condition with greater fat reserves may have negative health consequences such as hyperglycemia, as seen with increased GSP concentrations from raccoons in agricultural and barren landscapes. Broad scale analyses of body condition (Ontario and Québec) showed sex- specific results, where males were in better body condition in urban areas and females were in poorer body condition. Finer scale analyses of Ontario showed that raccoons from agricultural and barren landscapes were in poorer body condition than those from natural landscapes, which may provide insight into how raccoons conserve energy for locomotion. Males were found to be in consistently better body condition than females in Ontario. Surprisingly, there was no effect of urbanization in Québec potentially due to differences in municipal waste management policies. Overall, this study suggests a shift in diet from anthropogenic food waste to resources from agricultural and barren landscapes throughout the fall, as it is more readily available food source.