Calmest pigeon in Chicago

Parker and I saw this dude hopping in the brush next to a parking lot. By "saw," I mean Parker got close enough to give him a good sniff (but not close enough to chomp on him), which elicited not more from the bird than a disdainful look and continued pecking at the ground. I think he's a fledgling, though I'm puzzled by his coloring and by the tag on his right leg. Any ideas?