Rock Pigeon, Portland, Oregon, 19 February 2011 by Greg Gillson.
You may find the Rock Pigeon in older field guides listed as Rock Dove. Their name was recently changed.
Regardless, this is the common domestic pigeon. They are widely raised as free-flying "pets." However, they are also widely distributed as wild birds, breeding on highway overpasses, large bridges, and tall city buildings. You can find them in city parks in nearly every city in the world. They also breed on cliffs in remote settings.
The typical, "natural," plumage is blue-gray with wide dark wing bars and white rump--as in the photo above. They have been bred to be various colors and patterns, and even with feathered legs or odd neck ruffles or crests.
Though many people view these birds as dirty city birds, I can't help feeling a bit of attachment as they fly by--thanks to my favorite childhood movie, Mary Poppins!
Now where did I put my tuppence?