The bird in the backyard, separated from the human by a physical boundary, is considered a source of entertainment. If the same bird enters the house, control is lost, and it is suddenly perceived as an intruder. Once the bird is contained within a cage however, it becomes a beloved pet. What happens when the bird occupies the boundary between domestic and wild, establishing novel conditions of cohabitation?
The Expanded Environment, http://www.expandedenvironment.org