Shortly after we moved to Salt Lake City, I stepped out the back door and lo and behold! Two mature bald eagles flying over my backyard. Definitely NOT something I expected here! We used to see them a lot in Portland, OR when I lived there. I think if semi-suitable habitat is present, they just may show up. Habitat doesn't have to be pristine...I wouldn't say Salt Lake City is! (Though I think they must have been migrants.)