Urbanisation Facilitates Intrapopulation Dietary Niche Diversity in a Generalist Carnivore.

The niche variation hypothesis predicts that members of generalist species are specialists, and that the degree of individual specialisation correlates positively with resource diversity. Urban landscapes are highly heterogeneous in resource distribution; therefore, we predicted urbanisation would be associated with narrower individual dietary niches and greater differentiation among individuals of generalist species. We used stable isotope analysis to compare diets of urban and nonurban coyote (Canis latrans) populations in San Francisco and Marin County, California, USA. Urban coyotes had dietary niches nearly three times narrower than nonurban coyotes and greater among-individual variation in isotope values. Within-individual differences explained 18% of total δ13C variation in urban coyotes compared to 58% in nonurban coyotes, and 34% versus 44% of δ15N variation, indicating stronger individual specialisation in the urban population. Our findings suggest urbanisation facilitates intrapopulation dietary niche diversity by spatially structuring foraging, highlighting the role of human activity in promoting ecological diversification.