h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Columba livia, the Rock dove, is the standard pigeon seen all over the Mediterranean. Their natural nesting habitat is cliff walls, which is why they take to cities so well (tall brick or stone buildings). They've been domesticated for centuries and have spread throughout the globe by man's unintentional effort. They are all over North America and adapt very well to most environments.

Columba livia have been selectively bred to all varieties of show pigeon, such as homing pigeons, racers, tumblers, fan-tails, etc. Skinner popularized the use of this species of pigeon as a standard model for the study of behavior. Along with the lab rat (Rattus norvegicus), the pigeon has become widly used in the study of learning, memroy, categorization, and perception among other topics of psychological processes.

And the Stock Dove (Columba Oenas) is not the same species as the Rock Dove/Feral Pigeon (Columba Livia).