All I have to go on is the head, but can anyone tell me if this is a female purple martin or some type of swallow? I saw the bird sitting on top of the birdhouse about 2 weeks ago, but didn't have my camera with me at the time. (Shame on me.) The underside was completely white from the chin down. I did not see any green on the bird's back, just a deep iridescent indigo blue. Thanks for any clarification that you can offer.