We have (a new) winner - CIndy who left the comment "We have a lot of sparrows in the back yard, so I guess it would have to be them. Once, however, a huge raptor bird of some sort landed in the tree outside my living room window - caught it out of the corner of my eye. He flew off before The Google and I could identify him. Might have been a hawk of some sort."
Congratulations Cindy! Please email me at firstname.lastname@example.org with your details!!