The pigeon population of Paris, according to this site, was apparently introduced by pigeon-keepers in the 19th century; prior to that they were not urban birds, which is hard to imagine if you've been to any major world city. (The site also claims that there is one pigeon for every 25 Parisians.) Most of what you see is the ordinary city pigeon or Rock Dove, but one frequently sees a larger and slightly more stately bird with a rosy breast and white neck:
This is the Wood Pigeon (follow the link for better pictures) and it is a very attractive bird. There are a couple living in the tree outside our window. Its size makes it easier to understand how the pigeon could have been considered a game bird, and also why the raising of pigeons in urban areas became popular (much as the raising of rabbits, and for the same purpose).