ABSTRACT
Gray spaces are the human-constructed features unique to urbanization. Urbanization can be characterized as an increase in human habitation, coupled with increased per capita energy and resource consumption and extensive modification of the landscape, creating a system that does not depend principally on local natural resources to persist. Their list of structural features, unique to urbanization, included dwellings, factories, office buildings, warehouses, roads, pipelines, power lines, railroads, channelized stream beds, reservoirs, sewage disposal facilities, landfills, and airports. The chapter presents the four types of habitat in terms of increasing habitability to most native species and decreasing proportion of coverage toward the urban core: built habitat, managed vegetation, ruderal vegetation, and natural remnant vegetation. Wildlife encounters with buildings, windows, and towers can have both positive and negative consequences. The disruption of natural habitats by highways has measurable impacts on the population dynamics, survivability, and natural history of many wildlife species.
