Well, going by my extremely limited knowledge, she looks an awful lot like some of the pigeons I have seen on this board. She looks like Gem and Mira. So I vote pigeon, but again, I don't know much.
Very well could be someones Pet or a Loft bird.
Could also be a feral, does the bird seem friendly?
Whites are rare but do happen.
I have a pure white Feral here in my loft.
Arty
The little Piggie is doing well, I'm going to weigh him again in the morning (keeping a full flighted pigeon still on a scale is a barrel of monkeys-chasing him around the house is the best part) I'll post new pics too..Thank you for asking Arty : )