bwhahaha Nice.
As for the bird:
There are shitloads of domesticated dove and pigeons coming in far more varieties of colors and feathers than you can imagine. (Btw, they are so closely related, they may interbreed.) Since that one is banded and from the sound of it, not easily frightened, it probably belongs or belonged to someone at one time. Hard to say without seeing the actual tag. Even domesticated ones will take off on their own from time to time if they aren't kept roosted.
And, like other animals, it's possible for strange color variations in wild stock either due to a genetic abnormality or due to interbreeding with domesticated stock.