A couple of years ago I confirmed with a CO that pigeons are fair game in Ontario year round, and can be hunted with a small game license. Shooting feral/barnyard pigeons was a common practice in Ontario up until their numbers declined substantially in the 1960s due to all of the pesticides that farmers began to use until the first wave of the environmental movement successfully banned them in the early seventies. It took about another 10-15 years for them to become common again, though it seems as though most hunters today are unaware of their value as quarry, except for perhaps some European immigrants. A couple of years back I purchased several pigeon decoys from Al Flaherty's in Toronto, though I unfortunately never had the opportunity to use them.
In the UK, the species that is hunted there is known as Wood Pigeon, and is a major pest to farmers. It is consequently one of the few species of game available to hunters who haven't the time or money to commit to a club, syndicate or the commercial shoots that would probably cost them dearly. They can provide a considerable amount of shooting and good meat. The practice of releasing pigeons from a trap for people to shoot at is long gone from the UK, where the practice would surely draw a mob of animal rights fanatics who'd lynch anyone involved.....
Cheers,
Frank