ABSTRACT
This chapter describes the processes related to animal introductions in urban contexts. It also describes the main patterns and pathways of introduction and colonization, focuses on the precursors to success and establishment, and explores how these patterns led to the establishment of a particular subset of animal species. The chapter provides examples of the multiplicity of interactions that introduced animals can establish within the urban ecosystem, taking into account the potential cascade effects on animal communities and the social and sanitary interactions with humans and their pets. A key mechanism at the base of this observed replacement is obviously competition with native species. In freshwater ecosystems, the mosquitofish behaves as a voracious predator and it is often extremely abundant in disturbed habitats near urban areas. In terrestrial urban settings, bird populations can be dense in spite of feral cat predation.
