Isotopic Niche Analysis of Raccoon (Procyon lotor) Foraging Ecology across an Urban-To-Forest Landscape Gradient

The foraging ecology of opportunistic omnivores varies flexibly depending on the individual and habitat, particularly between urban and forest areas. In some Carnivora, the range of prey resources is reduced and trophic positions decrease in urban areas. Because raccoons (Procyon lotor) are highly flexible in their selection of prey, we hypothesized that they show similar dietary differences between habitat types to those of other carnivores. We assessed whether prey resource utilization changes in response to landscape structure based on isotopic signatures of fur samples from 72 individuals collected in Hyogo Prefecture. Regression analysis accounting for spatial autocorrelation showed that δ13C and δ15 N values are negatively correlated with the first principal component score representing the landscape structure within a 500 m radius, and increased in landscapes centered around urban areas. Our results suggest that raccoon prey resources were less diverse in urban regions of Hyogo than in natural landscapes and occupied higher trophic positions. Although there may be fewer opportunities to feed on prey resources at lower trophic positions, there are also reports of dependent behavior on anthropogenic prey resources; accordingly, it is possible that feeding opportunities and dependence on prey resources at higher trophic positions are increasing in urban areas. Published online 28 April, 2026; Print publication 31 July, 2026