Urban ecology, simply put, is the study of life in the city. In the late nineteenth century, biologists and zoologists created the field of ecology, seeking to understand the complex relationships between organisms and their environment. The term ecosystem started to be used to refer to a community of organisms and its associated environment when functioning as an ecological unit. Since then, the study of ecosystems has largely been associated with scientific descriptions of pristine locales, typically in remote regions where human presence was minimal to non-existent. In contrast, urban ecology is the study of urban ecosystems. In general, urban biodiversity is heavily dominated by alien species. There are exceptions, for instance suburban communities that retain parts of the pre-existing natural habitat, but overall, urban ecosystems are fundamentally anthropogenic, meaning that they are man-made.

Evidence of human action on the environment goes back thousands of years...