A prevailing image of the city is of the steel and concrete downtown skyline. The more common experience of urban residents, however, is a place of irrigated and fertilized green spaces, such as yards, gardens, and parks, surrounding homes and business‑ es where people commonly feed birds, squirrels, and other wildlife. Within these highly human-modified environments, researchers are becoming increasingly curious about how fundamental ecological phenomena play out, such as the feeding relationships among species. While food webs have long provided a tool for organizing information about feeding relationships and energy flows through natural habitats, they have not been applied to urban ecosystems until recently (Faeth et al. 2005).